advantages and disadvantages of literature review in research pdf

Advantages and disadvantages of literature review

This comprehensive article explores some of the advantages and disadvantages of literature review in research. Reviewing relevant literature is a key area in research, and indeed, it is a research activity in itself. It helps researchers investigate a particular topic in detail. However, it has some limitations as well.

What is literature review?

In order to understand the advantages and disadvantages of literature review, it is important to understand what a literature review is and how it differs from other methods of research. According to Jones and Gratton (2009) a literature review essentially consists of critically reading, evaluating, and organising existing literature on a topic to assess the state of knowledge in the area. It is sometimes called critical review.

A literature review is a select analysis of existing research which is relevant to a researcher’s selected topic, showing how it relates to their investigation. It explains and justifies how their investigation may help answer some of the questions or gaps in the chosen area of study (University of Reading, 2022).

A literature review is a term used in the field of research to describe a systematic and methodical investigation of the relevant literature on a particular topic. In other words, it is an analysis of existing research on a topic in order to identify any relevant studies and draw conclusions about the topic.

A literature review is not the same as a bibliography or a database search. Rather than simply listing references to sources of information, a literature review involves critically evaluating and summarizing existing research on a topic. As such, it is a much more detailed and complex process than simply searching databases and websites, and it requires a lot of effort and skills.

Advantages of literature review

Information synthesis

A literature review is a very thorough and methodical exercise. It can be used to synthesize information and draw conclusions about a particular topic. Through a careful evaluation and critical summarization, researchers can draw a clear and comprehensive picture of the chosen topic.

Familiarity with the current knowledge

According to the University of Illinois (2022), literature reviews allow researchers to gain familiarity with the existing knowledge in their selected field, as well as the boundaries and limitations of that field.

Creation of new body of knowledge

One of the key advantages of literature review is that it creates new body of knowledge. Through careful evaluation and critical summarisation, researchers can create a new body of knowledge and enrich the field of study.

Answers to a range of questions

Literature reviews help researchers analyse the existing body of knowledge to determine the answers to a range of questions concerning a particular subject.

Disadvantages of literature review

Time consuming

As a literature review involves collecting and evaluating research and summarizing the findings, it requires a significant amount of time. To conduct a comprehensive review, researchers need to read many different articles and analyse a lot of data. This means that their review will take a long time to complete.

Lack of quality sources  

Researchers are expected to use a wide variety of sources of information to present a comprehensive review. However, it may sometimes be challenging for them to identify the quality sources because of the availability of huge numbers in their chosen field. It may also happen because of the lack of past empirical work, particularly if the selected topic is an unpopular one.

Descriptive writing

One of the major disadvantages of literature review is that instead of critical appreciation, some researchers end up developing reviews that are mostly descriptive. Their reviews are often more like summaries of the work of other writers and lack in criticality. It is worth noting that they must go beyond describing the literature.

Key features of literature review

Clear organisation

A literature review is typically a very critical and thorough process. Universities usually recommend students a particular structure to develop their reviews. Like all other academic writings, a review starts with an introduction and ends with a conclusion. Between the beginning and the end, researchers present the main body of the review containing the critical discussion of sources.

No obvious bias

A key feature of a literature review is that it should be very unbiased and objective. However, it should be mentioned that researchers may sometimes be influenced by their own opinions of the world.

Proper citation

One of the key features of literature review is that it must be properly cited. Researchers should include all the sources that they have used for information. They must do citations and provide a reference list by the end in line with a recognized referencing system such as Harvard.

To conclude this article, it can be said that a literature review is a type of research that seeks to examine and summarise existing research on a particular topic. It is an essential part of a dissertation/thesis. However, it is not an easy thing to handle by an inexperienced person. It also requires a lot of time and patience.

Hope you like this ‘Advantages and disadvantages of literature review’. Please share this with others to support our research work.

Other useful articles:

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Last update: 08 May 2022

References:

Jones, I., & Gratton, C. (2009) Research Methods for Sports Shttps://www.howandwhat.net/new/evaluate-website-content/tudies, 2 nd edition, London: Routledge

University of Illinois (2022) Literature review, available at: https://www.uis.edu/learning-hub/writing-resources/handouts/learning-hub/literature-review (accessed 08 May 2022)

University of Reading (2022) Literature reviews, available at: https://libguides.reading.ac.uk/literaturereview/starting (accessed 07 May 2022)

Author: M Rahman

M Rahman writes extensively online and offline with an emphasis on business management, marketing, and tourism. He is a lecturer in Management and Marketing. He holds an MSc in Tourism & Hospitality from the University of Sunderland. Also, graduated from Leeds Metropolitan University with a BA in Business & Management Studies and completed a DTLLS (Diploma in Teaching in the Life-Long Learning Sector) from London South Bank University.

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What is it?

Literature reviews involve collecting information from literature that is already available, similar to a long essay. It is a written argument that builds a case from previous research (Machi and McEvoy, 2012). Every dissertation should include a literature review, but a dissertation as a whole can be a literature review. In this section we discuss literature reviews for the whole dissertation.

What are the benefits of a literature review?

There are advantages and disadvantages to any approach. The advantages of conducting a literature review include accessibility, deeper understanding of your chosen topic, identifying experts and current research within that area, and answering key questions about current research. The disadvantages might include not providing new information on the subject and, depending on the subject area, you may have to include information that is out of date.

How do I write it?

A literature review is often split into chapters, you can choose if these chapters have titles that represent the information within them, or call them chapter 1, chapter 2, ect. A regular format for a literature review is:

Introduction (including methodology)

This particular example is split into 6 sections, however it may be more or less depending on your topic.

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Systematic Reviews and Meta-analysis: Understanding the Best Evidence in Primary Healthcare

S. gopalakrishnan.

Department of Community Medicine, SRM Medical College, Hospital and Research Centre, Kattankulathur, Tamil Nadu, India

P. Ganeshkumar

Healthcare decisions for individual patients and for public health policies should be informed by the best available research evidence. The practice of evidence-based medicine is the integration of individual clinical expertise with the best available external clinical evidence from systematic research and patient's values and expectations. Primary care physicians need evidence for both clinical practice and for public health decision making. The evidence comes from good reviews which is a state-of-the-art synthesis of current evidence on a given research question. Given the explosion of medical literature, and the fact that time is always scarce, review articles play a vital role in decision making in evidence-based medical practice. Given that most clinicians and public health professionals do not have the time to track down all the original articles, critically read them, and obtain the evidence they need for their questions, systematic reviews and clinical practice guidelines may be their best source of evidence. Systematic reviews aim to identify, evaluate, and summarize the findings of all relevant individual studies over a health-related issue, thereby making the available evidence more accessible to decision makers. The objective of this article is to introduce the primary care physicians about the concept of systematic reviews and meta-analysis, outlining why they are important, describing their methods and terminologies used, and thereby helping them with the skills to recognize and understand a reliable review which will be helpful for their day-to-day clinical practice and research activities.

Introduction

Evidence-based healthcare is the integration of best research evidence with clinical expertise and patient values. Green denotes, “Using evidence from reliable research, to inform healthcare decisions, has the potential to ensure best practice and reduce variations in healthcare delivery.” However, incorporating research into practice is time consuming, and so we need methods of facilitating easy access to evidence for busy clinicians.[ 1 ] Ganeshkumar et al . mentioned that nearly half of the private practitioners in India were consulting more than 4 h per day in a locality,[ 2 ] which explains the difficulty of them in spending time in searching evidence during consultation. Ideally, clinical decision making ought to be based on the latest evidence available. However, to keep abreast with the continuously increasing number of publications in health research, a primary healthcare professional would need to read an insurmountable number of articles every day, covered in more than 13 million references and over 4800 biomedical and health journals in Medline alone. With the view to address this challenge, the systematic review method was developed. Systematic reviews aim to inform and facilitate this process through research synthesis of multiple studies, enabling increased and efficient access to evidence.[ 1 , 3 , 4 ]

Systematic reviews and meta-analyses have become increasingly important in healthcare settings. Clinicians read them to keep up-to-date with their field and they are often used as a starting point for developing clinical practice guidelines. Granting agencies may require a systematic review to ensure there is justification for further research and some healthcare journals are moving in this direction.[ 5 ]

This article is intended to provide an easy guide to understand the concept of systematic reviews and meta-analysis, which has been prepared with the aim of capacity building for general practitioners and other primary healthcare professionals in research methodology and day-to-day clinical practice.

The purpose of this article is to introduce readers to:

• The two approaches of evaluating all the available evidence on an issue i.e., systematic reviews and meta-analysis,
• Discuss the steps in doing a systematic review,
• Introduce the terms used in systematic reviews and meta-analysis,
• Interpret results of a meta-analysis, and
• The advantages and disadvantages of systematic review and meta-analysis.

Application

What is the effect of antiviral treatment in dengue fever? Most often a primary care physician needs to know convincing answers to questions like this in a primary care setting.

To find out the solutions or answers to a clinical question like this, one has to refer textbooks, ask a colleague, or search electronic database for reports of clinical trials. Doctors need reliable information on such problems and on the effectiveness of large number of therapeutic interventions, but the information sources are too many, i.e., nearly 20,000 journals publishing 2 million articles per year with unclear or confusing results. Because no study, regardless of its type, should be interpreted in isolation, a systematic review is generally the best form of evidence.[ 6 ] So, the preferred method is a good summary of research reports, i.e., systematic reviews and meta-analysis, which will give evidence-based answers to clinical situations.

There are two fundamental categories of research: Primary research and secondary research. Primary research is collecting data directly from patients or population, while secondary research is the analysis of data already collected through primary research. A review is an article that summarizes a number of primary studies and may draw conclusions on the topic of interest which can be traditional (unsystematic) or systematic.

Terminologies

Systematic review.

A systematic review is a summary of the medical literature that uses explicit and reproducible methods to systematically search, critically appraise, and synthesize on a specific issue. It synthesizes the results of multiple primary studies related to each other by using strategies that reduce biases and random errors.[ 7 ] To this end, systematic reviews may or may not include a statistical synthesis called meta-analysis, depending on whether the studies are similar enough so that combining their results is meaningful.[ 8 ] Systematic reviews are often called overviews.

The evidence-based practitioner, David Sackett, defines the following terminologies.[ 3 ]

• Review: The general term for all attempts to synthesize the results and conclusions of two or more publications on a given topic.
• Overview: When a review strives to comprehensively identify and track down all the literature on a given topic (also called “systematic literature review”).
• Meta-analysis: A specific statistical strategy for assembling the results of several studies into a single estimate.

Systematic reviews adhere to a strict scientific design based on explicit, pre-specified, and reproducible methods. Because of this, when carried out well, they provide reliable estimates about the effects of interventions so that conclusions are defensible. Systematic reviews can also demonstrate where knowledge is lacking. This can then be used to guide future research. Systematic reviews are usually carried out in the areas of clinical tests (diagnostic, screening, and prognostic), public health interventions, adverse (harm) effects, economic (cost) evaluations, and how and why interventions work.[ 9 ]

Cochrane reviews

Cochrane reviews are systematic reviews undertaken by members of the Cochrane Collaboration which is an international not-for-profit organization that aims to help people to make well-informed decisions about healthcare by preparing, maintaining, and promoting the accessibility of systematic reviews of the effects of healthcare interventions.

Cochrane Primary Health Care Field is a systematic review of primary healthcare research on prevention, treatment, rehabilitation, and diagnostic test accuracy. The overall aim and mission of the Primary Health Care Field is to promote the quality, quantity, dissemination, accessibility, applicability, and impact of Cochrane systematic reviews relevant to people who work in primary care and to ensure proper representation in the interests of primary care clinicians and consumers in Cochrane reviews and review groups, and in other entities. This field would serve to coordinate and promote the mission of the Cochrane Collaboration within the primary healthcare disciplines, as well as ensuring that primary care perspectives are adequately represented within the Collaboration.[ 10 ]

Meta-analysis

A meta-analysis is the combination of data from several independent primary studies that address the same question to produce a single estimate like the effect of treatment or risk factor. It is the statistical analysis of a large collection of analysis and results from individual studies for the purpose of integrating the findings.[ 11 ] The term meta-analysis has been used to denote the full range of quantitative methods for research reviews.[ 12 ] Meta-analyses are studies of studies.[ 13 ] Meta-analysis provides a logical framework to a research review where similar measures from comparable studies are listed systematically and the available effect measures are combined wherever possible.[ 14 ]

The fundamental rationale of meta-analysis is that it reduces the quantity of data by summarizing data from multiple resources and helps to plan research as well as to frame guidelines. It also helps to make efficient use of existing data, ensuring generalizability, helping to check consistency of relationships, explaining data inconsistency, and quantifies the data. It helps to improve the precision in estimating the risk by using explicit methods.

Therefore, “systematic review” will refer to the entire process of collecting, reviewing, and presenting all available evidence, while the term “meta-analysis” will refer to the statistical technique involved in extracting and combining data to produce a summary result.[ 15 ]

Steps in doing systematic reviews/meta-analysis

Following are the six fundamental essential steps while doing systematic review and meta-analysis.[ 16 ]

Define the question

This is the most important part of systematic reviews/meta-analysis. The research question for the systematic reviews may be related to a major public health problem or a controversial clinical situation which requires acceptable intervention as a possible solution to the present healthcare need of the community. This step is most important since the remaining steps will be based on this.

Reviewing the literature

This can be done by going through scientific resources such as electronic database, controlled clinical trials registers, other biomedical databases, non-English literatures, “gray literatures” (thesis, internal reports, non–peer-reviewed journals, pharmaceutical industry files), references listed in primary sources, raw data from published trials and other unpublished sources known to experts in the field. Among the available electronic scientific database, the popular ones are PUBMED, MEDLINE, and EMBASE.

Sift the studies to select relevant ones

To select the relevant studies from the searches, we need to sift through the studies thus identified. The first sift is pre-screening, i.e., to decide which studies to retrieve in full, and the second sift is selection which is to look again at these studies and decide which are to be included in the review. The next step is selecting the eligible studies based on similar study designs, year of publication, language, choice among multiple articles, sample size or follow-up issues, similarity of exposure, and or treatment and completeness of information.

It is necessary to ensure that the sifting includes all relevant studies like the unpublished studies (desk drawer problem), studies which came with negative conclusions or were published in non-English journals, and studies with small sample size.

Assess the quality of studies

The steps undertaken in evaluating the study quality are early definition of study quality and criteria, setting up a good scoring system, developing a standard form for assessment, calculating quality for each study, and finally using this for sensitivity analysis.

For example, the quality of a randomized controlled trial can be assessed by finding out the answers to the following questions:

• Was the assignment to the treatment groups really random?
• Was the treatment allocation concealed?
• Were the groups similar at baseline in terms of prognostic factors?
• Were the eligibility criteria specified?
• Were the assessors, the care provider, and the patient blinded?
• Were the point estimates and measure of variability presented for the primary outcome measure?
• Did the analyses include intention-to-treat analysis?

Calculate the outcome measures of each study and combine them

We need a standard measure of outcome which can be applied to each study on the basis of its effect size. Based on their type of outcome, following are the measures of outcome: Studies with binary outcomes (cured/not cured) have odds ratio, risk ratio; studies with continuous outcomes (blood pressure) have means, difference in means, standardized difference in means (effect sizes); and survival or time-to-event data have hazard ratios.

Combining studies

Homogeneity of different studies can be estimated at a glance from a forest plot (explained below). For example, if the lower confidence interval of every trial is below the upper of all the others, i.e., the lines all overlap to some extent, then the trials are homogeneous. If some lines do not overlap at all, these trials may be said to be heterogeneous.

The definitive test for assessing the heterogeneity of studies is a variant of Chi-square test (Mantel–Haenszel test). The final step is calculating the common estimate and its confidence interval with the original data or with the summary statistics from all the studies. The best estimate of treatment effect can be derived from the weighted summary statistics of all studies which will be based on weighting to sample size, standard errors, and other summary statistics. Log scale is used to combine the data to estimate the weighting.

Interpret results: Graph

The results of a meta-analysis are usually presented as a graph called forest plot because the typical forest plots appear as forest of lines. It provides a simple visual presentation of individual studies that went into the meta-analysis at a glance. It shows the variation between the studies and an estimate of the overall result of all the studies together.

Forest plot

Meta-analysis graphs can principally be divided into six columns [ Figure 1 ]. Individual study results are displayed in rows. The first column (“study”) lists the individual study IDs included in the meta-analysis; usually the first author and year are displayed. The second column relates to the intervention groups and the third column to the control groups. The fourth column visually displays the study results. The line in the middle is called “the line of no effect.” The weight (in %) in the fifth column indicates the weighting or influence of the study on the overall results of the meta-analysis of all included studies. The higher the percentage weight, the bigger the box, the more influence the study has on the overall results. The sixth column gives the numerical results for each study (e.g., odds ratio or relative risk and 95% confidence interval), which are identical to the graphical display in the fourth column. The diamond in the last row of the graph illustrates the overall result of the meta-analysis.[ 4 ]

Interpretation of meta-analysis[ 4 ]

Thus, the horizontal lines represent individual studies. Length of line is the confidence interval (usually 95%), squares on the line represent effect size (risk ratio) for the study, with area of the square being the study size (proportional to weight given) and position as point estimate (relative risk) of the study.[ 7 ]

For example, the forest plot of the effectiveness of dexamethasone compared with placebo in preventing the recurrence of acute severe migraine headache in adults is shown in Figure 2 .[ 17 ]

Forest plot of the effectiveness of dexamethasone compared with placebo in preventing the recurrence of acute severe migraine headache in adults[ 17 ]

The overall effect is shown as diamond where the position toward the center represents pooled point estimate, the width represents estimated 95% confidence interval for all studies, and the black plain line vertically in the middle of plot is the “line of no effect” (e.g., relative risk = 1).

Therefore, when examining the results of a systematic reviews/meta-analysis, the following questions should be kept in mind:

• Heterogeneity among studies may make any pooled estimate meaningless.
• The quality of a meta-analysis cannot be any better than the quality of the studies it is summarizing.
• An incomplete search of the literature can bias the findings of a meta-analysis.
• Make sure that the meta-analysis quantifies the size of the effect in units that you can understand.

Subgroup analysis and sensitivity analysis

Subgroup analysis looks at the results of different subgroups of trials, e.g., by considering trials on adults and children separately. This should be planned at the protocol stage itself which is based on good scientific reasoning and is to be kept to a minimum.

Sensitivity analysis is used to determine how results of a systematic review/meta-analysis change by fiddling with data, for example, what is the implication if the exclusion criteria or excluded unpublished studies or weightings are assigned differently. Thus, after the analysis, if changing makes little or no difference to the overall results, the reviewer's conclusions are robust. If the key findings disappear, then the conclusions need to be expressed more cautiously.

Advantages of Systematic Reviews

Systematic reviews have specific advantages because of using explicit methods which limit bias, draw reliable and accurate conclusions, easily deliver required information to healthcare providers, researchers, and policymakers, help to reduce the time delay in the research discoveries to implementation, improve the generalizability and consistency of results, generation of new hypotheses about subgroups of the study population, and overall they increase precision of the results.[ 18 ]

Limitations in Systematic Reviews/Meta-analysis

As with all research, the value of a systematic review depends on what was done, what was found, and the clarity of reporting. As with other publications, the reporting quality of systematic reviews varies, limiting readers’ ability to assess the strengths and weaknesses of those reviews.[ 5 ]

Even though systematic review and meta-analysis are considered the best evidence for getting a definitive answer to a research question, there are certain inherent flaws associated with it, such as the location and selection of studies, heterogeneity, loss of information on important outcomes, inappropriate subgroup analyses, conflict with new experimental data, and duplication of publication.

Publication Bias

Publication bias results in it being easier to find studies with a “positive” result.[ 19 ] This occurs particularly due to inappropriate sifting of the studies where there is always a tendency towards the studies with positive (significant) outcomes. This effect occurs more commonly in systematic reviews/meta-analysis which need to be eliminated.

The quality of reporting of systematic reviews is still not optimal. In a recent review of 300 systematic reviews, few authors reported assessing possible publication bias even though there is overwhelming evidence both for its existence and its impact on the results of systematic reviews. Even when the possibility of publication bias is assessed, there is no guarantee that systematic reviewers have assessed or interpreted it appropriately.[ 20 ]

To overcome certain limitations mentioned above, the Cochrane reviews are currently reported in a format where at the end of every review, findings are summarized in the author's point of view and also give an overall picture of the outcome by means of plain language summary. This is found to be much helpful to understand the existing evidence about the topic more easily by the reader.

A systematic review is an overview of primary studies which contains an explicit statement of objectives, materials, and methods, and has been conducted according to explicit and reproducible methodology. A meta-analysis is a mathematical synthesis of the results of two or more primary studies that addressed the same hypothesis in the same way. Although meta-analysis can increase the precision of a result, it is important to ensure that the methods used for the reviews were valid and reliable.

High-quality systematic reviews and meta-analyses take great care to find all relevant studies, critically assess each study, synthesize the findings from individual studies in an unbiased manner, and present balanced important summary of findings with due consideration of any flaws in the evidence. Systematic review and meta-analysis is a way of summarizing research evidence, which is generally the best form of evidence, and hence positioned at the top of the hierarchy of evidence.

Systematic reviews can be very useful decision-making tools for primary care/family physicians. They objectively summarize large amounts of information, identifying gaps in medical research, and identifying beneficial or harmful interventions which will be useful for clinicians, researchers, and even for public and policymakers.

Source of Support: Nil

Conflict of Interest: None declared.

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Conducting a Literature Review

Benefits of conducting a literature review.

• Steps in Conducting a Literature Review
• Summary of the Process
• Additional Resources
• Literature Review Tutorial by American University Library
• The Literature Review: A Few Tips On Conducting It by University of Toronto
• Write a Literature Review by UC Santa Cruz University Library

While there might be many reasons for conducting a literature review, following are four key outcomes of doing the review.

Assessment of the current state of research on a topic . This is probably the most obvious value of the literature review. Once a researcher has determined an area to work with for a research project, a search of relevant information sources will help determine what is already known about the topic and how extensively the topic has already been researched.

Identification of the experts on a particular topic . One of the additional benefits derived from doing the literature review is that it will quickly reveal which researchers have written the most on a particular topic and are, therefore, probably the experts on the topic. Someone who has written twenty articles on a topic or on related topics is more than likely more knowledgeable than someone who has written a single article. This same writer will likely turn up as a reference in most of the other articles written on the same topic. From the number of articles written by the author and the number of times the writer has been cited by other authors, a researcher will be able to assume that the particular author is an expert in the area and, thus, a key resource for consultation in the current research to be undertaken.

Identification of key questions about a topic that need further research . In many cases a researcher may discover new angles that need further exploration by reviewing what has already been written on a topic. For example, research may suggest that listening to music while studying might lead to better retention of ideas, but the research might not have assessed whether a particular style of music is more beneficial than another. A researcher who is interested in pursuing this topic would then do well to follow up existing studies with a new study, based on previous research, that tries to identify which styles of music are most beneficial to retention.

Determination of methodologies used in past studies of the same or similar topics.  It is often useful to review the types of studies that previous researchers have launched as a means of determining what approaches might be of most benefit in further developing a topic. By the same token, a review of previously conducted studies might lend itself to researchers determining a new angle for approaching research.

Upon completion of the literature review, a researcher should have a solid foundation of knowledge in the area and a good feel for the direction any new research should take. Should any additional questions arise during the course of the research, the researcher will know which experts to consult in order to quickly clear up those questions.

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Improving the peer review of narrative literature reviews

• Jennifer A. Byrne 1 , 2  

Research Integrity and Peer Review volume  1 , Article number:  12 ( 2016 ) Cite this article

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As the size of the published scientific literature has increased exponentially over the past 30 years, review articles play an increasingly important role in helping researchers to make sense of original research results. Literature reviews can be broadly classified as either “systematic” or “narrative”. Narrative reviews may be broader in scope than systematic reviews, but have been criticised for lacking synthesis and rigour. The submission of more scientific manuscripts requires more researchers acting as peer reviewers, which requires adding greater numbers of new reviewers to the reviewing population over time. However, whereas there are many easily accessible guides for reviewers of primary research manuscripts, there are few similar resources to assist reviewers of narrative reviews. Here, I summarise why literature reviews are valued by their diverse readership and how peer reviewers with different levels of content expertise can improve the reliability and accessibility of narrative review articles. I then provide a number of recommendations for peer reviewers of narrative literature reviews, to improve the integrity of the scientific literature, while also ensuring that narrative review articles meet the needs of both expert and non-expert readers.

Peer Review reports

Over the past 30 years, the size of the published scientific literature has expanded exponentially [ 1 ]. While it has been argued that this rate of expansion is unsustainable [ 2 ], underlying factors such as greater numbers of scientists and scientific journals [ 3 ] are unlikely to change in the short term. The submission of more manuscripts for publication requires more peer reviewers, yet the current demand for capable, available manuscript reviewers is not being met [ 3 ]. This has serious adverse consequences for the validity of published research and overall trust in science [ 3 ].

Review articles help both experts and non-experts to make sense of the increasing volume of original publications [ 4 , 5 ]. Busy clinicians have a particular reliance upon review articles, because of their constant need for reliable, up-to-date information, yet limited available time [ 6 ]. Literature reviews can also help other content experts such as researchers and policymakers to identify gaps in their own reading and knowledge. However, literature reviews are also sought by readers with little or no prior understanding of the reviewed topic, such as researchers seeking to rapidly triage results from high-throughput analyses and students for whom literature reviews can represent entry points into a new field. For the benefit of both expert and non-expert readers, it is essential that review articles accurately synthesise the relevant literature in a comprehensive, transparent and objective manner [ 7 , 8 ].

Numbers of review articles are increasing in fields where this has been measured [ 4 ], as is the diversity of review types published [ 9 , 10 ]. Although there are now many review sub-types that can be distinguished based upon the literature search, appraisal, synthesis and analysis methods used [ 9 , 10 ], review articles can be broadly classified as either “systematic” or “narrative” [ 5 , 11 ]. Systematic reviews take defined approaches to the identification and synthesis of study findings and include other review sub-types such as evidence maps [ 12 ]. The systematic review is considered to be the gold standard of evidence synthesis, but also carries the potential disadvantages of narrow scope [ 11 ], and requiring more time and resources to prepare and update [ 7 ]. Narrative reviews, also referred to as “traditional reviews” [ 5 ] and “literature reviews” [ 9 ], constitute the majority of review articles published in some fields [ 7 ]. Other review sub-types, such as rapid and scoping reviews also present information in a narrative format [ 9 ]. Narrative reviews have been criticised for rarely employing peer-reviewed methodologies, or duplicate curation of evidence [ 5 ], and for often failing to disclose study inclusion criteria [ 11 ]. Despite these limitations, narrative reviews remain frequent within the literature, as they offer breadth of literature coverage and flexibility to deal with evolving knowledge and concepts [ 11 ]. In this article, I will provide advice regarding the peer review of narrative reviews, and the advice presented aims to be broadly applicable. I will not attempt to provide advice regarding the peer review of systematic reviews [ 13 , 14 ].

Given the broad readership of literature reviews, content and methodology experts as well as reviewers with less directly relevant expertise can play important roles in the peer-review process [ 15 ]. Peer reviewers with related content expertise are best placed to assess the reliability of the information presented, while other reviewers can ensure that this information remains accessible to readers with different levels of prior knowledge. However, whereas there are easily accessible guides for reviewers of primary research manuscripts [ 16 , 17 ], there are few similar resources available for reviewers of literature reviews [ 15 , 18 ]. This article therefore proposes a number of recommendations for peer reviewers (Table  1 ) to ensure that narrative literature review articles make the best possible contributions to their fields, while also meeting their readers’ often diverse needs.

Ask whether the literature review justifies its place in the literature

Lower than expected ratios between numbers of original publications and review articles suggest excessive numbers of reviews in some fields, which may contribute to the very problem that review articles aim to solve [ 4 ]. With rapidly rising publication rates in many fields [ 2 ], even content-expert peer reviewers should check publication databases for similar and/or overlapping review articles as part of the peer-review process. Pre-empting such scrutiny, authors should clearly define the review’s scope and what it intends to achieve [ 8 ]. If there have been other recent reviews of the same or similar topics, the authors should explain how their manuscript is unique. This could be through combining literature from related fields, by updating existing reviews in light of new research evidence [ 8 ], or because published reviews may have been subject to bias. A clear definition of a review’s scope is a recognised tool to reduce evidence selection bias [ 19 ]. Review authors can also define their subject by referring to literature reviews of related topics that will not be explored in depth. These definitions and statements should form part of an overall narrative structure that helps readers to anticipate and understand the information presented [ 20 ].

Ask whether the literature searches conducted were clearly defined

A criticism frequently levelled at traditional or narrative reviews is that they do not always state or follow rules regarding literature searches [ 5 , 7 , 11 ]. Providing evidence that comprehensive literature searches have been conducted, preferably according to pre-defined eligibility criteria [ 19 ], increases confidence that the review’s findings and conclusions are reliable, and have not been subject to selection bias. Ideally, any literature search choices made by the authors should be clearly stated, transparent and reproducible [ 11 ].

Check for citation breadth and balance

Consider whether the authors have cited a comprehensive range of literature or whether they have tended to cite papers that support their own point of view. If there are important papers that have not been cited, suggest to the authors that these be added, and explain why. If only a limited number of articles can be cited due to the journal’s requirements, check that these studies are representative of those available.

Where possible, verify that information has been summarised correctly

Many different types of citation errors can be identified in the research literature [ 21 , 22 ], and these may occur regardless of the journal impact factor [ 22 ]. The increasing size and complexity of primary reports [ 3 ] also render data extraction and summary more challenging. Realistically, it is unlikely that individual peer reviewers will have detailed knowledge of any full review topic [ 19 ]. Nonetheless, if you are a content expert, take time to cross-reference at least some individual statements to citations, for the particular benefit of non-expert readers. If your level of expertise means that you are unable to verify the accuracy of particular sections of the review, you should indicate this to your editor. Peer reviewers can also ask about data extraction methods, if these were not described in the manuscript. Adopting systematic review practices, such as duplicate independent data extraction, or independent data extraction and validation, can reduce content errors and increase reliability [ 19 ].

Check that original references have been cited

Authors sometimes incorrectly cite original studies, both in original manuscripts and reviews [ 23 , 24 ]. While checking the content, ask whether descriptions of original findings were referenced accordingly, as opposed to being incorrectly attributed to reviews [ 23 ].

Consider how studies were critically evaluated

Beyond correct data summary, narrative literature reviews should include critical data appraisal and some level of data synthesis. How this should be done varies according to the review scope and methodology [ 9 , 10 , 19 ]. While some narrative reviews reasonably focus on breadth as opposed to depth of literature coverage [ 10 ], limited or poor data appraisal risks placing undue emphasis on poor quality research [ 9 ]. Evaluating at least some aspects of the methods used by individual studies can improve reliability [ 7 ]. Similarly, ask how the authors have interpreted conflicting findings or studies with apparently outlying results [ 9 , 11 ].

Evaluate whether tables/figures/diagrams support the text

While not all literature reviews need to include figures or tables, these can help to summarise findings and make key messages clearer. Some detailed information may be best presented in tables, with a shorter summary within the text. Tables can improve the availability of quantitative data for cross-checking, better demonstrate the results of qualitative or quantitative data synthesis, and reassure both peer reviewers and readers that comprehensive, objective analyses have been performed. If figures or tables are included, these need to be original; otherwise, the authors need to have obtained permission to reproduce these from an original source.

Consider whether the review will help someone entering the field

Literature reviews are not always read by subject experts, and it is important that the peer-review process considers this. Reviewers who are not direct content experts may valuably request clarification of nomenclature and/or historical issues that may have seemed too obvious for the authors to have explained. Summary diagrams suggested by peer reviewers may help make a literature review more accessible to a broader audience.

Ask whether the review expands the body of knowledge

Ultimately, the goal of a literature review should be to further the body of knowledge [ 18 ]. Extending or developing ideas is clearly a difficult task, and is often the weakest section of a review [ 25 ]. Consider therefore whether the authors have derived and clearly presented new ideas and/or new research directions from any identified knowledge gaps. Having read the manuscript with fresh eyes, peer reviewers may have valuable ideas to contribute.

Do not forget the rules for reviewing manuscripts in general

The review of literature reviews has some particular considerations, but all the usual manuscript review rules also apply, such as managing conflicts of interest and allocating appropriate time [ 16 , 17 ]. Try to separate the assessment of language and grammar from the more important assessment of scientific quality and remain aware that expert reviewers risk bringing their own biases to the peer-review process [ 15 ].

Conclusions

More quality peer reviewers are needed within the scientific community [ 3 ], including those with the capacity and confidence to review narrative literature reviews. Although it has been difficult to identify predictors of peer-reviewer performance and effective training methods, younger reviewer age has been reproducibly associated with better quality manuscript reviews [ 26 , 27 ]. This association suggests that peer reviewers should be recruited relatively early in their careers, and encouraged to participate widely in manuscript review. Associations between younger peer-reviewer age and better manuscript reviews may also highlight the need for regular training, to ensure that the peer-review community remains up-to-date regarding new approaches to editing or reviewing manuscripts. Indeed, a recent industry survey reported that over three quarters of researchers were interested in further reviewer training [ 28 ]. I therefore hope that this article will add to existing resources [ 29 ] to encourage less experienced peer reviewers to extend their efforts towards narrative literature reviews.

Bornmann L, Mutz R. Growth rates of modern science: a bibliometric analysis based on the number of publications and cited references. J Assoc Inform Sci Tech. 2015;66(11):2215–22.

Google Scholar  

Pautasso M. Publication growth in biological sub-fields: patterns, predictability and sustainability. Sustainability. 2012;4(12):3234–47.

Article   Google Scholar  

Siebert S, Machesky LM, Insall RH. Overflow in science and its implications for trust. Elife. 2015;4: doi: 10.7554/eLife.10825 .

Ketcham CM, Crawford JM. The impact of review articles. Lab Invest. 2007;87(12):1174–85.

Dijkers MP. Task Force on Systematic Reviews and Guidelines. The value of traditional reviews in the era of systematic reviewing. Am J Phys Med Rehabil. 2009;88(5):423–30.

McAlister FA, Clark HD, van Walraven C, Straus SE, Lawson FM, Moher D, et al. The medical review article revisited: has the science improved? Ann Intern Med. 1999;131(12):947–51.

Haddaway NR, Woodcock P, Macura B, Collins A. Making literature reviews more reliable through application of lessons from systematic reviews. Conserv Biol. 2015;29(6):1596–605.

Pautasso M. Ten simple rules for writing a literature review. PLoS Comput Biol. 2013;9(7):e1003149.

Grant MJ, Booth A. A typology of reviews: an analysis of 14 review types and associated methodologies. Health Inform Lib J. 2009;26(2):91–108.

Paré G, Trudel M-C, Jaana M, Kitsiou S. Synthesizing information systems knowledge: a typology of literature reviews. Inform Management. 2015;52(2):183–99.

Collins JA, Fauser BCJM. Balancing the strengths of systematic and narrative reviews. Hum Reprod Update. 2005;11(2):103–4.

Miake-Lye IM, Hempel S, Shanman R, Shekelle PG. What is an evidence map? A systematic review of published evidence maps and their definitions, methods, and products. Syst Rev. 2016;5:28.

Higgins JPT, Green S. Handbook for systematic reviews of interventions. The Cochrane Collaboration, John Wiley & Sons Ltd; 2011.

Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gøtzsche PC, Ioannidis JP, et al. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate healthcare interventions: explanation and elaboration. BMJ. 2009;339:b2700.

Oxman AJ. Checklists for review articles. BMJ. 1994;309(6955):648–51.

Bourne PE, Korngreen A. Ten simple rules for reviewers. PLoS Comput Biol. 2006;2(9):e110.

Nicholas KA, Gordon W. A quick guide to writing a solid peer review. Eos. 2011;92(28):233–4.

Jennex ME. Literature reviews and the review process: an editor-in-chief’s perspective. CAIS. 2015;36:8.

O’Connor A, Sargeant J. Research synthesis in veterinary science: narrative reviews, systematic reviews and meta-analysis. Vet J. 2015;206(3):261–7.

Docherty M, Smith R. The case for structuring the discussion of scientific papers. BMJ. 1999;318(7193):1224–5.

Davids JR, Weigl DM, Edmonds JP, Blackhurst DW. Reference accuracy in peer-reviewed pediatric orthopaedic literature. J Bone Joint Surg Am. 2010;92(5):1155–61.

Awrey J, Inaba K, Barmparas G, Recinos G, Teixeira PG, Chan LS, et al. Reference accuracy in the general surgery literature. World J Surg. 2011;35(3):475–9.

Gavras H. Inappropriate attribution: the “lazy author syndrome”. Am J Hypertens. 2002;15(9):831.

Katz TJ. Propagation of errors in review articles. Science. 2006;313(5791):1236.

Webster J, Watson RT. Analyzing the past to prepare for the future: writing a literature review. MIS Q. 2002;26:2.

Black N, van Rooyen S, Godlee F, Smith R, Evans S. What makes a good reviewer and a good review for a general medical journal? JAMA. 1998;280(3):231–3.

Callaham ML, Tercier J. The relationship of previous training and experience of journal peer reviewers to subsequent review quality. PLoS Med. 2007;4(1):e40.

Warne V. Rewarding reviewers- sense or sensibility? A Wiley study explained. Learned Pub. 2016;29(1):41–50.

COPE Ethical Guidelines for Peer Reviewers. Available: http://publicationethics.org/resources/guidelines-new/cope-ethical-guidelines-peer-reviewers . Accessed 10 Aug, 2016.

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Acknowledgements

I thank Dr Mona Shehata (Princess Margaret Cancer Centre, Toronto, Canada) for discussions, Ms Sarah Frost for critical reading, reviewers of this manuscript for many constructive comments, and reviewers of past publications for feedback which also contributed towards the development of this manuscript.

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Strengths and Weaknesses of Systematic Reviews

Automate every stage of your literature review to produce evidence-based research faster and more accurately.

Systematic reviews are considered credible sources since they are comprehensive, reproducible, and precise in stating the outcomes. The type of review system used and the approach taken depend on the goals and objectives of the research. To choose the best-suited review system, researchers must be aware of the strengths and weaknesses of each one.

Let us now look at the strengths and limitations of systematic reviews.

Strengths Of Systematic Reviews

Systematic reviews have become increasingly popular owing to their transparency, accuracy, replicability, and reduced risk of bias. Some of the main benefits of systematic reviews are;

Specificity

Researchers can answer specific research questions of high importance. For example, the efficacy of a particular drug in the treatment of an illness.

Explicit Methodology

A systematic review requires rigorous planning. Each stage of the review is predefined to the last detail. The research question is formulated using the PICO (population, intervention, comparison, and outcome) approach. A strict eligibility criteria is then established for inclusion and exclusion criteria for selecting the primary studies for the review. Every stage of the systematic review methodology is pre-specified to the last detail and made publicly available, even before starting the review process. This makes all the stages in the methodology transparent and reproducible.

Reliable And Accurate Results

The results of a systematic review are either analyzed qualitatively and presented as a textual narrative or quantitatively using statistical methods such as meta-analyses and numeric effect estimates. The quality of evidence or the confidence in effect estimates is calculated using the standardized GRADE approach.

Comprehensive And Exhaustive

A systematic review involves a thorough search of all the available data on a certain topic. It is exhaustive and considers every bit of evidence in synthesizing the outcome. Primary sources for the review are collected from databases and multiple sources, such as blogs from pharmaceutical companies, unpublished research directly from researchers, government reports, and conference proceedings. These are referred to as grey literature. The search criteria and keywords used in sourcing are specific and predefined.

Reproducible

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Weaknesses Of Systematic Reviews

Although systematic reviews are robust tools in scientific research they are not immune to errors. They can be misleading, or even harmful if the data is inappropriately handled or if they are biased. Some of the limitations of systematic reviews include:

Mass Production

Due to the popularity systematic reviews have gained, they tend to be used more than required. The growth rate of systematic reviews has outpaced the growth rate of studies overall. This results in redundancy. For example, a survey published in the BMJ[1], included 73 randomly selected meta-analyses published in 2010 found that for two-thirds of these studies, there was at least one, and sometimes as many as 13, additional meta-analyses published on the same topic by early 2013.

Risk of Bias

Although systematic reviews have many advantages, they are also more susceptible to certain types of biases. A bias is a systematic or methodological error that causes misrepresentation of the study outcomes. As bias can appear at any stage, authors should be aware of the specific risks at each stage of the review process. Most of the known errors in systematic reviews arise in the selection and publication stages. The eligibility criterion in a systematic review helps to avoid selection bias. Poor study design and execution can also result in a biased outcome. It’s important to learn about the types of bias in systematic reviews .

Expressing Strong Opinions by Stealth

Selective outcome reporting is a major threat to a systematic review. The author or reviewer may decide to only report a selection of the statistically significant outcomes that suit his interest. The possibility of unfair or misleading interpretation of evidence outcomes in a systematic review can have serious implications.

Like any review system, systematic reviews have their advantages and disadvantages. Understanding them is essential to making a choice of which review system to use.

Overlapping meta-analyses on the same topic: survey of published studies. BMJ 2013; 347:f4501

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• Published: 03 June 2024

A comprehensive review of sustainable materials and toolpath optimization in 3D concrete printing

• Zicheng Zhuang 1   na1 ,
• Fengming Xu 1   na1 ,
• Junhong Ye 1   na1 ,
• Liming Jiang 3 &
• Yiwei Weng 1  

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• Climate sciences
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The construction sector has experienced remarkable advancements in recent years, driven by the demand for sustainable and efficient building practices. Among these advancements, 3D concrete printing has emerged as a highly promising technology that holds the potential to revolutionize the construction industry. This review paper aims to provide a comprehensive analysis of the latest developments in three vital areas related to 3D concrete printing: sustainable materials, structural optimization, and toolpath design. A systematic literature review approach is employed based on established practices in additive manufacturing for construction to explore the intersections between these areas. The review reveals that material recycling plays a crucial role in achieving sustainable construction practices. Extensive research has been conducted on structural optimization methodologies to enhance the performance and efficiency of 3D printed concrete structures. In the printing process, toolpath design plays a significant role in ensuring the precise and efficient deposition of concrete. This paper discusses various toolpath generation strategies that take factors such as geometric complexity, printing constraints, and material flow control into account. In summary, the insights presented in this paper may serve as guidelines for researchers, engineers, and industry professionals towards sustainable and efficient construction practices using 3D concrete printing technology.

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Introduction.

Climate change has emerged as a global challenge due to the substantial carbon emissions and energy consumption. In 2022, the global carbon emissions and energy consumption reached 36.8 gigatons and 14,585 million tonnes of oil equivalent 1 , 2 , respectively. The construction sector is a major contributor to global carbon emission and energy consumption, accounting for 40% and 36% in 2022 3 , respectively. With the urban population estimated to increase to 68% by 2050, the environmental impacts of the construction sector will continuously increase 4 , underscoring the urgent need for developing sustainable construction technologies.

3D concrete printing (3DCP), also known as additive manufacturing (AM) in the construction sector 5 , offers a promising solution for achieving sustainable construction. 3DCP constructs structures by depositing printable concrete materials layer-atop-layer based on a pre-designed building model. The unique construction process possesses the advantages of enhanced sustainability and design flexibility. For example, a prefabricated bathroom unit (PBU) constructed by 3DCP achieved a reduction of 85.9% and 87.1% in carbon emissions and energy consumption, respectively, compared to that of a mold-cast counterpart 6 .

3DCP has gained much attention from both academia and engineering. Figure 1a shows the rapid growth in the publications and citations related to the keywords of “3DCP” based on data obtained from Web of Science. The number of publications reached 444 and 420 in 2022 and 2023, respectively. In these publications, several review works have been conducted in the fields of 3DCP and its potential applications 7 , 8 , 9 , 10 . Wangler et al. 8 present a technical review of 3DCP from fresh materials to hardened materials and further practical applications. Lu et al. 9 provide a comprehensive review of the material behaviors of 3DCP. However, the review articles primarily focus on the technical or material advancements of 3DCP, with less attention given to its sustainability aspects. Figure 1b illustrates the growth of publications related to the keywords of “3DCP and Sustainability”. Despite the growing interest in 3DCP, only 46 publications in 2023, approximately 10% of total 3DCP-related publications, focused on sustainability (Fig. 1a ). Among these publications, Dey et al. 11 provide a comprehensive review of the utilization of industrial wastes in printable materials to improve the sustainability of 3DCP. However, there is a lack of in-depth understanding of how to improve sustainability in 3DCP across its various construction processes.

a Keywords of “3DCP”; b keywords of “3DCP and Sustainability”.

The typical construction processes of 3DCP include the development of printable materials, structural optimization, toolpath design, and printing 12 , as shown in Fig. 2 . Each of these processes offers opportunities for enhancing sustainability. At the material level, sustainability can be improved by developing printable materials incorporated with waste materials. The waste materials are used as the substitutions of aggregate and binder contents, thereby reducing the carbon emission associated with the material extraction. At the structural level, the design of hollow structures via topology optimization (TO) 13 , 14 reduces the material usage and thus enhances sustainability. TO involves the optimization of material distribution to achieve the desired performance. In addition, the design flexibility of 3DCP is compatible with the structural TO. Finally, to implement the optimized structure into 3DCP, toolpath design methods 15 , 16 are adopted to determine the efficient path for sustainable concrete printing. The integration of sustainable printable materials, TO, and toolpath design techniques with 3DCP represents a promising synergy for future research and sustainability development in the construction sector. However, comprehensive reviews covering these three aspects are currently lacking in the existing literature.

The typical processes include the development of printable materials, structural optimization, toolpath generation, and printing.

This paper aims to fill the abovementioned research gap by providing a comprehensive review of sustainable materials, structural topology optimization, and toolpath planning for the enhancement of sustainability in 3DCP. Based on the findings of these reviewed articles, the perspectives and methods to enhance sustainability with respect to the abovementioned three aspects of 3DCP are highlighted. Finally, Section 5 conclusions are summarized and future research directions are identified.

Sustainable materials in 3D concrete printing

Integrating sustainable materials into 3DCP is a potential strategy for enhancing the sustainability of 3DCP 17 since the construction sector increasingly focuses on the recycling of natural resources, reduction in material waste and carbon emissions. The commonly developed 3D printable cementitious materials consist of binder materials (primarily cement), natural fine aggregates, additives, admixtures, and water 18 . However, two main challenges impede the development of sustainable 3D printable cementitious materials. Firstly, the high usage of ordinary Portland cement (OPC, 700–800 kg/m 3 ) 18 impacts sustainability due to the associated carbon footprint 8 . Secondly, during the printing process, most developed material mixtures only use fine aggregates for 3DCP due to the limitation of the pumping process and nozzle opening 19 , 20 .

Employing sustainable binder and aggregate alternatives is a potential solution to address these challenges 6 , 21 . This section reviews relevant advancements in adopting recycled aggregates and supplementary cementitious materials (SCMs) into 3D printable materials. Figure 3 shows the number of publications associated with the keywords “3D printed concrete”, “Recycled glass”, “Recycled sand”, “Recycled concrete aggregate”, “Recycled plastics”, “Recycled rubber”, “3D printed concrete”, “Silica fume”, “Rice husk”, “Fly ash”, “Limestone”, “Calcined clay”, “Granulated blast-furnace slag” and “Sustainable” from the Web of Science database. As shown in Fig. 3 , a growing academic interest is observed related to recycled aggregates and SCMs. The following sections discuss the performance characteristics and implications of these sustainable materials in 3DCP applications.

The literature study includes research on two main types of sustainable materials, recycled aggregates and SCM, from 2018 to 2023.

The impact of recycled aggregates, such as recycled glass 22 , concrete 23 , plastics 24 , and rubber 25 , alongside SCMs, such as silica fume 26 , rice husk ash 27 , fly ash 28 , limestone 29 , calcined clay 30 , and granulated blast-furnace slag (GGBS) 31 , on the fresh and hardened properties of 3D printable materials are analyzed. The analysis underscores the importance of these materials in advancing 3DCP sustainability but also reveals the future potential research direction to mitigate environmental impacts and foster sustainable development in 3D printable cementitious materials 19 , 32 , 33 .

3D printable material performance with recycled aggregates

The primary recycled materials in 3D printed concrete for sustainability enhancement include sand 34 , glass 22 , concrete 35 , plastics 24 , and rubber 25 . According to the data from the Hong Kong Environmental Protection Department in 2022 36 , daily waste generation in Hong Kong includes 222.6 tons of glass and 2336.9 tons of plastics. In addition, concrete and sand, derived mainly from construction and demolition debris and construction waste, account for a considerable portion of the waste, with daily production of construction waste reaching 49,865 tons 36 . In the blueprint for Hong Kong 2035 37 , the government proposes a new target concerning “Waste Reduction, Resources Circulation, Zero Landfill”, which presents a significant challenge for the recycling of waste materials in sustainable construction.

In 3DCP, it is essential to achieve a balance of fresh properties and hardened properties for printable materials. Fresh properties such as printability and pumpability, hardened properties such as strength and durability, and sustainability are critical factors for material tailoring 19 , 38 . Recycled aggregates are sustainable alternatives to natural aggregates, helping to conserve natural resources and reduce land waste from landfills 24 , 39 , 40 , 41 . This section discusses the various recycled aggregates in 3DCP (see Table 1 for details) to illustrate their impact on material fresh and hardened performance as well as sustainability.

Impacts of recycled aggregates on fresh properties

Summarizing the findings from Table 1 , the usage of recycled aggregates impacts the fresh properties of cementitious materials. The fresh properties are critical factors, which determine the printability of materials during the printing process. The printability can be characterized by workability, pumpability, extrudability, and buildability 34 . In the 3D printing process, the most essential steps are conveying mixed materials to the nozzle via a delivery system and depositing materials to build the solid object in a layer-by-layer manner 42 . In the conveying step, the materials are required to have good workability and pumpability, which indicates how easily the material can be conveyed. In addition, extrudability indicates the ability of a material to be extruded with minimal energy consumption during the delivery 43 . In the deposition step, the materials are required to have good buildability, which indicates how well the materials can be stacked stably.

With respect to workability, research has indicated that the presence of recycled sand, characterized by its high water absorption rate and irregular shape, tends to reduce the workability of concrete 44 . Similarly, incorporating recycled rubber particles with poor shape and rough surfaces has diminished the workability of 3D printed concrete, resulting in the slow relative motion of rubber particles within the concrete mixture, causing reduced processability 25 . In terms of pumpability, studies conducted by Ting et al. 45 have shown that adding recycled glass to concrete reduces its pumpability. This phenomenon can be attributed to recycled glass particles’ angular and sharp-edged nature, which obstruct flow and decrease pumpability.

Analyzing the extrudability in recycled aggregate concrete, it has been observed that the high water absorption of recycled sand necessitates the addition of extra water and superplasticizers to enhance the extrudability of 3D printed concrete 34 . In addition, the water-absorbing nature of surface cracks in recycled rubber can result in reduced extrudability. However, subjecting recycled rubber to heat treatment can partially close these surface cracks, reducing water absorption and significantly improving extrudability 46 .

Finally, with respect to buildability, increasing the substitution rate of recycled concrete aggregates has been found to improve the buildability of 3D printed concrete. Liu et al.’s 35 research suggests that the buildability increases with the rising substitution rate of recycled concrete aggregates due to the reduction in concrete density. Conversely, studies involving recycled plastics have revealed that while plastic’s hydrophobic nature enhances material flow, it also delays the hydration reaction of calcium silicate, slowing the thixotropic behavior of concrete and ultimately reducing its buildability 24 , 41 .

In summary, recycled aggregates’ influence on cementation materials’ fresh properties is multifaceted and crucial for 3D printing applications. Workability can be compromised by recycled sand and rubber, while pumpability may be hindered when using recycled glass due to its angular characteristics. Extrudability can be improved with additional water and heat treatment for specific recycled materials. In addition, buildability is positively correlated with higher substitution rates of recycled concrete aggregates, while challenges arise from the delayed hydration reaction of calcium silicate when recycled plastics are involved. These insights underscore the need for careful material selection and processing adjustments to optimize the performance of 3D printable materials.

Impacts of recycled aggregates on mechanical properties and sustainability

The mechanical performance of printed structures is paramount for ensuring their structural integrity and safety. Table 1 summarizes the mechanical properties of various types of recycled aggregates, revealing their impact on the mechanical properties of 3D printed concrete. Specifically, incorporating recycled materials such as recycled sand, coarse aggregates, glass, and plastics as sustainable alternatives in concrete leads to decreased compressive strength with increasing substitution rates 22 , 24 , 34 , 35 . This reduction in compressive strength can be attributed to the increased porosity within the concrete resulting from the addition of recycled materials, with higher porosity leading to reduced compressive strength 24 , 39 .

Beyond the problem of increased porosity, the bond between recycled aggregates and the cement matrix plays a significant role in the mechanical performance of 3D printed concrete. The smoother surface and sharper edges of recycled glass particles compared to that of natural sand particles may result in weaker bonding between the particles and the cement matrix at the interface transition zone, decreasing mechanical strength 45 . The inherent properties of recycled aggregates also impact the strength of 3D printed concrete. Recycled concrete aggregates containing old mortar and aggregates with adhering old mortar, which have lower mechanical properties, can serve as weak areas of a structure, decreasing mechanical performance 35 . On the contrary, adding cement-coated modified recycled rubber in 3D printed concrete enhances its compressive strength. This enhancement is primarily attributed to the transformation of the rubber from a hydrophobic material to a hydrophilic material after modification, promoting its interaction with the fresh mortar during mixing and resulting in a more compact interface transition zone within the structure 33 .

These findings emphasize the necessity of incorporating recycled aggregates in 3D printed concrete in appropriate amounts after considering the structural integrity and safety to achieve the desired overall properties of 3D printed concrete. As a type of sustainable material, utilizing recycled aggregates in 3DCP can reduce material costs and mitigate environmental impacts 47 . Han et al. indicate that as the proportion of recycled aggregates increases from 0% to 100%, the CO 2 emissions of 3D printed concrete decrease from 5637.647 kg to 5499.505 kg 48 . Cost analyses demonstrate a downward trend in the total cost of 3D printed concrete with the increasing proportion of recycled aggregates. For instance, the costs of 3D printed concrete with recycling proportions of 0%, 50%, and 100% are 12,913.54 CNY, 12,555.77 CNY, and 12,194.97 CNY, respectively 48 . This underscores that increasing the proportion of recycled aggregates can effectively reduce greenhouse gas emissions during concrete production and enhance building materials’ sustainability in the practical application.

3D printable material performance with supplementary cementitious materials

This section explores the impact of supplementary cementitious materials (SCMs) on the performance of 3D printable cementitious materials. In the area of 3DCP, a significant aspect is its heavy reliance on OPC compared to traditional concrete 18 . Specifically, 3D printable cementitious materials contain more than 20% of OPC, expressed by mass weight due to the requirements of printability 19 . Including SCMs in material mixtures is an alternative solution to address his problem. Various types of SCMs have been adopted for the mixture design of 3D printable concrete in the existing literature, such as fly ash, ground granulated blast furnace slag, and calcined clay from various industrial processes 49 . Fly ash, a residue from coal combustion in power plants 50 , and calcined clay, derived from high-temperature treatment of clay materials 29 , are among these industrially sourced SCM. In addition, GGBS originates from the milling process of waste slag from steel production 51 , while silica fume comes from silicon ferroalloy smelting 52 , and rice husk ash is a by-product of rice milling 27 . Incorporating these SCMs reduces the environmental burden associated with concrete production and addresses the high carbon dioxide emissions from cement production 29 , 53 .

In the selection of SCMs for 3D printable concrete, optimizing characteristics such as fresh properties, mechanical properties, durability, and sustainability is crucial 29 , 30 , 54 . These attributes directly impact the efficiency of the printing process and the performance of the final structure. Table 2 summarizes the material characteristics of individual SCM used in 3DCP and their impacts on the performance of 3D printable concrete by a systematic literature review.

Impacts of SCMs on fresh properties

Based on Table 2 , the utilization of SCMs affects the printability of 3D printed concrete. These parameters serve as crucial indicators of the stability and performance of materials during processes such as pumping, extrusion, and bearing continuous printing layer loads. In terms of workability, adding silica fume reduces the workability of 3D printed concrete. This is primarily attributed to the high surface area of silica fume, which easily aggregates with cement particles to form flocculent structures, partially hindering the free flow of water, and therefore, affecting the workability 26 , 53 .

In terms of pumpability and extrudability, the appropriate addition of fly ash and GGBS can enhance the pumpability and extrudability of cementitious materials. This is primarily attributed to the spherical and smooth surface characteristics of fly ash 55 and GGBS 56 , as shown in Table 2 , and therefore, contribute to improving the extrudability of concrete. However, excessive fly ash and GGBS may diminish extrudability due to increased water absorption. As the dosage increases, the water absorption rate rises, resulting in increased viscosity, thereby impeding the extrusion process during 3D printing 57 . The replacement of cement with silica fume 26 , rice husk ash 27 , limestone, and calcined clay 29 can enhance buildability. For example, torque viscosity rises while flow resistance and thixotropy are decreased with the rise of fly ash-to-cement ratio, negatively impacting the buildability 55 . Conversely, the influence of the silica fume-to-cement ratio shows an opposite trend on rheological properties as compared to that of the fly ash-to-cement ratio. Adding silica fume increases the filler content in concrete, strengthening the interaction between particles and thereby improving the 3D printing performance of the material 50 . Rice husk ash exhibits strong water absorption capability, reducing voids between concrete particles and promoting flocculation and hydration product formation, thereby enhancing the buildability of 3D printed concrete 27 . The addition of limestone and calcined clay can enhance the buildability due to the reduced water film thickness 30 .

In summary, incorporating SCMs significantly impacts the workability, pumpability, extrudability, and buildability of 3D printed concrete. While silica fume reduces workability due to its high surface area 26 , fly ash and GGBS can enhance pumpability and extrudability when added appropriately. However, excessive amounts may hinder extrudability due to increased water absorption 57 . Substituting cement with fly ash, silica fume, rice husk ash, limestone, and calcined clay enhances buildability 26 , 27 , 58 .

Impacts of SCMs on mechanical properties and sustainability

The mechanical performance of 3D printed concrete is crucial for construction practices. Incorporating SCMs can reduce the environmental impact and directly influence the mechanical properties of 3D printed concrete. Studies have shown that materials such as silica fume 26 , limestone, and calcined clay 29 can positively impact the mechanical properties of concrete. Silica fume acts as an inert filler in 3D printed concrete, filling voids, improving pore structure, and therefore, enhancing mechanical performance 50 . Liu et al. 26 attributed the improvement in the mechanical properties of silica fume to the fact that silica fume increases the density of the concrete, which increases the pore densities and reduces the number of connecting and oversized pores.

Moreover, the quantity of SCMs added also affects the mechanical properties of 3D printed concrete. Increasing the content of limestone and calcined clay can increase the amount of fine particles in concrete, promoting microstructure development 54 . However, small additions of fly ash and GGBS can enhance mechanical properties but excessive amounts may compromise concrete strength. This is mainly due to that the high amount of replacement of cement with fly ash or GGBS reduces the initial cement hydration at the early stage 57 . As a result, the mechanical performance of 3D printable concrete decreases. Therefore, when designing formulations for 3D printed concrete, it is essential to consider the type, quantity, and interactions of SCMs to achieve optimal mechanical performance and ensure the sustainability and durability of structures.

In 3DCP, the CO 2 emission in the material production stage is 583.1 kg CO 2 -eq/m 3 , 75% of which is contributed by the production of cement and other binder materials 18 . Therefore, using SCMs as the substitution of binder materials showed possible advantages in enhancing the environmental sustainability of 3D printable concrete 26 , 28 , 54 . Most of the reviewed studies focus on the fresh and hardened properties of 3D printable concrete with SCMs, with limited attention to the quantitative carbon emission assessment of the materials. Long et al. 59 reported that the 3D printable Limestone & Calcined clay cement composites (LC3) reduced carbon emission by 45% and energy consumption by 40%. Conversely, Yao et al. 60 reported that the carbon emission of printable materials was when geopolymer was used as the binder material. The increased carbon emission of geopolymer was due to the use of silicate (alkaline activator). Liu et al. 61 reported that the printable materials with fly ash showed less carbon emission compared to that of the printable geopolymer concrete. Different conclusions were drawn from the existing articles in terms of the carbon emission of 3D printable materials with SCM. Therefore, to comprehensively assess the sustainability effectiveness of SCMs in 3DCP, additional research is necessary in future works by conducting the quantitative carbon emission assessment.

Conventional structural topology optimization methods

Traditional design principles and considerations are being re-evaluated to leverage the unique capabilities provided by 3D printing 62 . This section aims to review the specific structural optimization methods and considerations tailored for 3DCP technology, with a particular focus on the potential to create functional, efficient, and sustainable designs using topology optimization approaches.

Structural topology optimization is the process of arranging the distribution of materials within a specified design domain to maximize specific mechanical or physical properties, while adhering to prescribed constraints. This concept arose in 1904 when Michell proposed a theoretical analysis to obtain the lightest truss 63 . The advent of finite element analysis (FEA) and the development of the widely used homogenization method 64 , 65 in the late 1980s significantly progressed this concept. Since then, the field has seen substantial advancements, thanks to methods such as Solid Isotropic Microstructure with Penalization (SIMP) 66 , Evolutionary Structural Optimization (ESO) 67 , Bi-directional Evolutionary Structural Optimization (BESO) 68 , 69 , and level set method 70 , 71 . These developments have allowed for more sophisticated and efficient designs and further expanded the possibilities of structural topology optimization. As shown in Table 3 , the various topology optimization approaches have continuously evolved to improve their effectiveness and efficiency, which are introduced individually in this section.

After the introduction of the homogenization-based topology optimization method by Bendsoe and Kikuchi 64 and later developments by Bendsoe 72 , the SIMP method was proposed 73 , 74 . Sigmund 75 provided a clear explanation of the numerical implementation of the SIMP method in 2001 using a concise 99-line Matlab code. The SIMP method assumes constant material properties for the solid material within the design domain. The design variables in the optimization process are the relative densities of each element, which range between zero and one. The material properties are modeled as the relative material density raised to a power multiplied by the properties of the solid material. During the early 1990s, Xie and Steven initially put forth the Evolutionary Structural Optimization (ESO) method to attain optimal topologies for continuum structures 67 , 76 , 77 . Subsequently, Querin et al. 68 and Yang et al. 78 advanced the ESO method to develop the Bi-directional Evolutionary Structural Optimization (BESO) method. The level set-based topology optimization method utilizes a higher-dimensional embedded function to implicitly represent solid-void interfaces 79 , 80 . In the traditional level set method, the Hamilton-Jacobi equation (PDE) is solved using the velocity normal to the interface 71 , 81 , 82 . The zero-level contour of the embedded function in the conventional level set method defines the material boundary, serving as the partition between the solid and void domains.

Advanced structural topology optimization methods

In recent years, a variety of innovative optimization algorithms have emerged to tackle the practical challenges associated with flexible design domains, smooth material boundaries, and complex fabrication constraints. One such method is the Reaction diffusion-based level set (RDLS) approach, which was initially introduced in 2014 83 . The RDLS method enables the specification of geometrical complexities within the optimal configuration, thereby facilitating the identification of the desired structure shape through the evolution of the level set function. Another notable advancement is the Floating projection topology optimization (FPTO) method, which was unveiled in 2021 84 . FPTO ensures that design variables take discrete values, resulting in more robust and practical optimization outcomes. Lastly, the Node moving-based topology optimization (NMTO) method, introduced in 2023 85 utilizes a narrowband offset from the structural profile to establish a signed-distance function, which determines the direction of node movement. NMTO aims to optimize the structural topology and enhance its overall performance by manipulating node positions. These cutting-edge methods show great promise for advancing the capabilities of 3DCP and optimizing the production of high-performance structures.

Nowadays, structural topology optimization has become increasingly popular in various fields, including additive manufacturing 69 , 86 , architectural design 87 , 88 , biochemical 89 , 90 , and aerospace engineering 91 , 92 . Among them, the high design flexibility of 3DCP makes it compatible with topology optimization to decrease material usage and improve sustainability. With the integration of these approaches and 3DCP, it becomes possible to create intricate designs that are both structurally sound and resource-efficient.

To find an appropriate method for 3DCP, the benefits and limitations of each topology optimization method should be fully understood, which are introduced and summarized in this subsection. The key scientific differences between the various topology optimization methods include mathematical formulation, optimization algorithms, material models, sensitivity analysis, and post-processing techniques.

The advantages and disadvantages of these topology optimization methods can be concluded to judge whether they can be integrated with 3DCP to fabricate efficient and environmentally friendly structures. For instance, the homogenization method allows for accurate computation of material properties using a systematic approach to obtain optimal topology. However, it may not be suitable for structures with complex material distributions and may struggle with handling geometric complexities. The SIMP method is advantageous as it provides a simple and effective way to model material properties and incorporate manufacturing constraints. Nevertheless, it produces designs with intermediate densities and may suffer from numerical instabilities. Next, the ESO method offers improved utilization of material resources by gradually removing ineffective material but may require a large number of iterations and struggle with complex geometries. Similarly, the BESO method efficiently optimizes structures by employing fundamental strategies but may produce designs with checkerboard patterns and require careful parameter tuning. On the other hand, the conventional level set method utilizes higher-dimensional embedded functions to implicitly represent solid-void interfaces accurately, which can handle topological changes during the optimization process. Nonetheless, it requires careful handling of interface tracking to avoid spurious geometries and may suffer from numerical diffusion and grid-related issues.

On the other hand, the RDLS method allows for specifying geometrical complexity but requires significant computational resources. Besides, this method is sensitive to parameter settings. The FPTO method incorporates floating projection constraints and heuristically simulates 0/1 constraints of design variables, leading to discrete and practical solutions, that provide robust optimization results by considering upper and lower bounds. However, the method’s heuristic nature may not guarantee global optimality, and it may require careful tuning of parameters to balance feasibility and optimality. The NMTO method establishes a signed-distance function to determine node-moving directions, allowing for efficient topology optimization, complex structure design, and flexibility in node manipulation. The disadvantage of the NMTO method is that it may struggle with handling complex boundary conditions and geometric constraints. These are just some general advantages and disadvantages of the topology optimization methods mentioned.

In summary, the suitability of each method regarding 3DCP depends on specific applications and requirements. Different topology optimization methods employ various mathematical formulations to represent and solve the optimization problem. Each formulation has its advantages and limitations in terms of modeling flexibility, convergence behavior, and computational efficiency. Besides, topology optimization methods may differ in the sensitivity analysis approach employed to evaluate the influence of design changes on the objective function and constraints. After obtaining an optimized design, different methods employ various post-processing techniques to interpret and convert the obtained results into manufacturable forms. These techniques can include filtering, mesh smoothing, or shape reconstruction algorithms. The selection of post-processing techniques impacts the final quality, manufacturability, and practicality of the optimized design.

Structural topology optimization in 3D concrete printing

Structural topology optimization has been widely applied in the field of 3DCP, due to the benefits to create efficient and optimized structures. By combining these two techniques, engineers can maximize the use of material, reduce weight, and enhance load-bearing capabilities, resulting in more sustainable and cost-effective structures.

The emergence of 3DCP technology has revolutionized the field of structural design by providing unprecedented freedom in creating intricate geometries and customized structures 93 . This capability opens up new opportunities for designers to push the boundaries of traditional design principles 94 , 95 . By harnessing the inherent freedom of design, 3DCP can create structures that are aesthetically appealing and optimized for performance and functionality 87 . For instance, the optimization of material distribution in 3DCP is a vital research direction to minimize material waste and optimize structural efficiency 14 , 96 . Since the last decade, structural topology optimization has been increasingly applied in 3DCP 97 , 98 . Figure 4 shows the research article number in the last decade integrating different topology optimization approaches and 3DCP using the keywords “3D printed concrete”, “Homogenization method”, “SIMP method”, “ESO method”, “BESO method”, “Level set method”, and “Phase field method” based on data obtained from the Web of Science database. This section focuses on the approaches that have been explored to achieve structural topology optimization in 3DCP. These include using additive manufacturing techniques to build complex geometries and incorporating reinforcement elements during the printing process 14 , 86 , 99 . Existing works 96 , 97 have demonstrated the ability to optimize the internal structure of concrete components, resulting in improved mechanical properties and enhanced performance.

The literature study includes research on the application of six typical optimization methods from 2014 to 2024.

The integration of topology optimization and 3DCP has the potential to enhance the performance and resource efficiency of buildings. With the increasing emphasis on sustainable and eco-friendly practices, optimized structural design has emerged as a critical strategy to reduce material usage while maintaining structural strength 99 , 100 . For instance, the varying physical properties present in functionally graded materials can be customized to meet specific requirements, all while making efficient use of material resources 101 . Building on the multi-material BESO method, a novel approach to 3DCP structural design was introduced 102 . In this approach, 3DPC components primarily experience compression without the need for extra reinforcement. Instead, they synergistically collaborate with tensioned steel cables to create an effective composite structural system. The previous study 96 examined the production process of a topology-optimized 3D printed concrete bridge structure, highlighting its significant deviation from the manufacturing procedures of conventional concrete structures. Yang et al. 103 presented an integrated design method for 3DCP by incorporating extrusion-based manufacturing characteristics into the topology optimization algorithm. Lightweight structures tend to have better seismic performance, increased durability, and reduced energy consumption compared to their heavier counterparts 61 . In addition, lighter structures require less foundation support, resulting in cost savings during construction 104 . Since construction activities are responsible for a significant amount of carbon emissions, reducing the amount of material used can significantly decrease the carbon footprint of a building.

Several examples of a combination of topology optimization and waste materials have been achieved using additive manufacturing 105 , 106 . These technologies provide benefits including minimized waste materials, accelerated construction timelines, and the capacity to create distinctive designs with intricate details. In addition, they classify large-scale 3DCP technologies, emphasizing the importance of optimizing printing ink to enhance economic and environmental results by utilizing waste materials in 3DCP applications. The combination of topology optimization and waste materials offers numerous benefits. Firstly, it promotes sustainable design practices by utilizing recycled or waste materials, contributing to the circular economy and reducing waste. Secondly, it helps reduce costs as waste materials are often less expensive or even available for free compared to conventional materials. In addition, incorporating waste materials into the design improves resource efficiency by minimizing the need for extracting and processing new materials. Moreover, the unique properties of waste materials can enhance the performance of the optimized design, such as strength, durability, or lightweight. This combination also encourages innovation and creativity by exploring unconventional design solutions.

In summary, the integration of topology optimization and 3DCP can enhance the performance and resource efficiency of buildings. The impact of structural lightweighting on seismic performance, durability, and energy consumption makes it a compulsory consideration in achieving resource efficiency. In terms of future research directions, further advancements in structural topology optimization for 3DCP are anticipated. This includes developing advanced algorithms that can handle anisotropic, large-scale optimization problems and integrating multi-material printing capabilities. In addition, research efforts could focus on exploring the potential of bio-inspired design principles and incorporating functional requirements such as interlocking, thermal insulation, and acoustic performance into the optimization process.

Toolpath design and optimization in 3D concrete printing

Toolpath design is a critical aspect of 3DCP as it directly impacts the quality, efficiency, and structural integrity of the printed components. Firstly, toolpath design takes into account material-related problems, such as the flowability and workability of the concrete mixture. By carefully planning the toolpath, engineers can ensure that the material is properly deposited, minimizing problems, such as clogging or inconsistent layering. Toolpath design also addresses process-related concerns, such as the prevention of sagging or deformation during printing. Optimizing the toolpath by the integration of factors such as load-bearing capabilities, stress distribution, and reinforcement placement, can enhance the structural integrity of the printed components.

Toolpath planning determines the success of the 3DCP process. Toolpath design involves mapping out the trajectory and deposition strategy of the printing toolhead to ensure accurate material placement and optimal structural integrity 101 , 107 , 108 . By carefully coordinating the movement of the toolhead, designers can achieve precise layering, intricate geometries, improved sustainability, and desired material properties in the printed structure. Xia et al. 109 proposed an integrated design method to improve the mechanical performance and manufacturability of material extrusion structures according to the technical characteristics of material extrusion. The technical aspects of toolpath planning encompass various considerations, such as path optimization 110 , 111 , 112 , layer sequencing 113 , 114 , manufacturing constraints 14 , 115 , 116 , and support structure generation 86 , 117 , 118 .

Figure 5 illustrates the number of publications during the past decade related to the keywords “3D printed concrete”, “Extrusion-based toolpath design”, “Geometric toolpath design”, “Toolpath visualization”, “Manufacturing constraints”, “Topology optimization-based toolpath design”, “Sliced toolpath design”, and “Toolpath design efficiency/performance” based on data obtained from the Web of Science database. Path optimization algorithms aim to minimize print time, reduce material waste, and enhance printing efficiency by optimizing the toolhead’s movement trajectory. Layer sequencing determines the order in which layers are printed to ensure stability and prevent collapse during the printing process. Material flow control involves adjusting the printing parameters, such as nozzle speed and extrusion rate, to achieve consistent material deposition and avoid defects. Lastly, support structure generation ensures the stability of overhanging or complex geometries during printing.

The literature study includes research on different toolpath design approaches from 2016 to 2024.

In recent years, there have been key research developments 14 , 15 , 96 , 119 in toolpath design and optimization. One of the key areas of focus has been on optimizing toolpaths for material efficiency and print time reduction. Researchers have explored various toolpath design methods with the instruction of topology optimization to achieve efficient and environmentally friendly structures. In addition, advancements in path optimization algorithms 110 , 111 , 112 , layer sequencing 113 , 114 , and support structure generation 86 , 117 , 118 have helped to enhance the printing efficiency and accuracy of 3DCP. Two novel printing techniques, “knitting” and “tilting” filaments, were proposed to address the anisotropy inherent in 3D printed ECC, emulating the natural crossed-lamellar structure of conch shells 120 . Three-dimensional spatial paths were devised to distribute tensile and flexural resistance in multiple directions and establish an interwoven interface system to enhance the strength of the structure.

The integration of toolpath design, 3D concrete printing, and topology optimization

Toolpath planning includes the strategic arrangement of the printing toolhead’s movement paths and deposition patterns to achieve the desired structural form 121 , 122 , 123 , 124 . This section aims to highlight the significance of toolpath planning in 3DCP and topology optimization. Existing methods for toolpath design in 3DCP involve a combination of computational algorithms, simulation techniques, and empirical knowledge. These methods consider various constraints and challenges, including printer limitations 14 , geometric complexity 16 , surface finish requirements 125 , overhang (self-support) problem 86 , interlocking 126 , and stability 127 during the printing process. They aim to generate toolpaths that maximize printing efficiency while ensuring the structural integrity and quality of the final product.

The toolpath design methods displayed in Fig. 5 can be integrated with 3DCP to fabricate efficient and high-performance structures depending on the fabrication requirements. Extrusion-based toolpath design in 3D concrete printing refers to the process of planning and creating the specific paths along which the extrusion nozzle will move to deposit layers of concrete material in a three-dimensional printed structure. Extrusion-based toolpath design 128 , 129 offers several advantages. It allows for the generation of toolpaths tailored to the specific material deposition process, resulting in efficient and optimized printing trajectories. By considering the extrusion process, this method can minimize print time, reduce material waste, and enhance printing efficiency. However, it may be limited in its ability to handle complex geometries and struggle with intricate support structure generation. Geometric toolpath design 16 , 130 focuses on creating toolpaths based on the geometric characteristics of the part being printed. This approach can lead to precise toolpaths that align with the part’s geometry, potentially reducing material waste. However, it may be less effective in optimizing toolpaths for overall printing efficiency and may struggle with handling complex layer sequencing. Toolpath visualization 131 , 132 provides a visual representation of the toolpaths, aiding in the identification of potential issues such as collisions, inefficient trajectories, or inadequate support structures. While it can help in identifying and addressing these issues, it may not actively optimize the toolpaths for print time, material waste, or printing efficiency. This method allows for precise control over layer sequencing and material flow control, ensuring stable and accurate printing. However, it may require additional computational resources and not fully optimize toolpaths for overall printing efficiency.

Toolpath design can be integrated with topology optimization to generate better performance 103 , 133 . Topology optimization-based toolpath design integrates the principles of topology optimization into the generation of toolpaths. By considering material deposition constraints and printing process dynamics, this method aims to create toolpaths that are not only geometrically optimized but also aligned with manufacturing constraints and support structure requirements. This approach can lead to highly efficient toolpaths that minimize print time, material waste, and enhance overall printing efficiency.

In summary, each of these toolpath design methods offers unique advantages and considerations. The selection of the most suitable method depends on the specific printing requirements, material characteristics, geometric complexity, and manufacturing constraints of the part being printed.

Benefits and challenges for future applications

The impact of toolpath optimization on the quality and efficiency of 3DCP has garnered significant attention. This section aims to analyze how optimized toolpaths positively influence printing quality and efficiency, emphasizing the reduction of waste and energy consumption. Advanced algorithms and computational models 119 , 127 , 134 are being developed to strategically plan the movement paths and deposition patterns of the printing toolhead, enabling precise material placement and optimized structural performance. A well-planned toolpath can result in structurally sound and aesthetically pleasing printed structures, while inadequate planning can lead to issues like material sagging, poor bonding between layers, or excessive material use 15 , 135 , 136 . Therefore, understanding and optimizing the toolpath planning process is vital for successful and reliable 3DCP 137 , 138 . Furthermore, toolpath planning also provides opportunities for customization and innovation in construction 16 , 125 . With the ability to precisely control the deposition pattern and material properties, designers can explore novel architectural forms, integrate functional features, and optimize performance characteristics.

Through systematic toolpath planning, it becomes possible to mitigate issues such as over-extrusion, uneven material distribution, and inaccuracies in layer deposition, ultimately leading to superior printing quality 112 , 139 . Moreover, the relationship between toolpath planning and material efficiency is paramount in the context of sustainable manufacturing practices. Optimized toolpaths contribute to the reduction of material waste and energy consumption by streamlining the printing process. Efficient toolpaths enable precise material deposition, minimize unnecessary movements, and optimize the use of support structures, thereby reducing material consumption and enhancing overall sustainability in 3DCP 132 , 140 , 141 .

The technical considerations involved in toolpath optimization for 3DCP encompass path optimization algorithms, print speed adjustments, and support structure generation. Path optimization algorithms aim to minimize print time and reduce material waste by optimizing the toolhead’s movement trajectory, while print speed adjustments ensure consistent material flow and deposition 132 . In addition, support structure generation and layer sequencing contribute to the stability and efficiency of the printing process 86 . Real-world case studies provide valuable insights into the benefits and challenges associated with toolpath optimization in construction projects 142 , 143 .

In terms of future research directions, there is a requirement to address additional constraints for the practical usage of 3DCP. For instance, the development of artificial intelligence empowered toolpath design methods for structures with complex geometric features. The integration of real-time monitoring and feedback systems into the toolpath design process can help improve accuracy and adaptability during printing. In addition, considering sustainability aspects, such as the use of recycled materials or minimizing waste, presents another avenue for future research in toolpath design for 3DCP.

Conclusions

This study presents a comprehensive overview of three vital aspects integrated with 3D concrete printing (3DCP) that contribute to enhancing sustainability in the construction sector. The first area of focus is sustainable material, which involves optimizing the constituents of printable materials through the recycling of waste materials into aggregates and supplementary cementitious materials. This approach reduces the environmental impact of the materials but also enhances the economic viability of 3DCP. The second vital area discussed is structural optimization, which plays a crucial role in maximizing structural performance and efficiency by rearranging material distribution. This optimization leads to improved structural integrity, reduced material usage, and minimized construction time and cost. Lastly, advances in toolpath planning have significantly improved the quality and efficiency of 3DCP. By strategically planning the movement paths and deposition patterns of the printing toolhead, toolpath optimization enhances printing accuracy, minimizes defects, and improves overall structural integrity. Furthermore, the review article also explores the influence of printing parameters on the quality and integrity of printed structures, providing valuable insights for future research and development in the field. By investigating the synergies between these three elements, this research aims to provide valuable insights for advancing sustainable and efficient building practices through the implementation of 3DCP technology.

The future of 3DCP in the construction sector is promising, while more systematic works are required to facilitate the practical application and sustainability of 3DCP:

Integration of Advanced Technologies: Future research should focus on integrating advanced technologies such as artificial intelligence and robotic control into toolpath optimization. These technologies can be adopted in the material design, system integration, and real-time optimization of printing processes.

Development of New Algorithms: There is a need for the development of new algorithms for toolpath optimization that can address specific challenges in 3DCP, such as handling complex geometries, optimizing material flow, and managing overhangs. These algorithms should also aim to optimize multiple objectives simultaneously.

Exploration of Novel Applications: Future research should explore novel applications of toolpath optimization in construction, such as printing complex architectural forms, integrating functional features, and creating customized structures. The potential of toolpath optimization in challenging environments, such as underwater or in space, should also be investigated.

Systematic literature review

This review article employs a systematic literature review approach based on established practices in additive manufacturing for construction to explore the intersections between 3DCP, material sustainability, structural topology optimization, and toolpath design. The Web of Science Core Collection, including indices such as SCI, SSCI, SCI-Expanded, and ESCI, is utilized to gather diverse publications until December 2023, encompassing journal articles, conference proceedings, books, and reports. A three-stage review method is meticulously designed to ensure objectivity and reproducibility.

Initially, relevant keywords, including “3D concrete printing,” “sustainable material,” “structural topology optimization,” and “toolpath design,” are defined to ensure a focused review. The literature reviews for sustainable material, TO, and toolpath design sections are conducted independently by different researchers. In the first stage, 1033 papers related to 3DCP are identified, with further breakdowns of 400 papers for sustainable material, 472 for structural topology optimization, and 161 for toolpath design. In the second stage, manual screening is conducted based on predefined criteria, including methodology robustness, published year, bibliographic information, and sustainability considerations. Comparative analysis results in the identification of 476 papers, comprising 245 for sustainable material, 136 for structural topology optimization, and 95 for toolpath design, as displayed in Figs. 3 , 4 , and 5 . In the third stage, the literature was further narrowed down to 160 references for inclusion in this review according to the specific criteria, including published journals, impact in the field, and number of citations. This three-step screening procedure guarantees that the literature review remains focused and relevant.

An analytical synthesis is then performed to summarize the primary studies of additive manufacturing in construction. The 160 studies obtained by the screening procedure are integrated systematically and classified into three sections according to their context, study design, and outcomes. The references cited in the sections on sustainable material, structural topology optimization, and toolpath design are 61, 76, and 23, respectively. In conclusion, the systematic literature review methodology minimizes reliance on subjective judgments, mitigates personal biases and errors, and upholds the integrity of scholarly research 144 .

Data availability

No datasets were generated or analyzed during the current study.

I.E. Agency. CO 2 Emissions in 2022 . https://www.iea.org/reports/co2-emissions-in-2022 (2023).

Enerdata. World Energy & Climate Statistics—Yearbook 2022 . World Energy Consumption Statistics| Enerdata France. https://yearbook.enerdata.net/total-energy/world-consumption-statistics.html (2022).

C.I. Council. Sustainable Construction . https://www.sc.cic.hk/index.php/en/ (2023).

Khan, S. A., Koç, M. & Al-Ghamdi, S. G. Sustainability assessment, potentials and challenges of 3D printed concrete structures: a systematic review for built environmental applications. J. Clean. Prod. 303 , 127027 (2021).

Article   Google Scholar  

Tay, Y. W. D. et al. 3D printing trends in building and construction industry: a review. Virtual Phys. Prototyp. 12 , 261–276 (2017).

Weng, Y. et al. Comparative economic, environmental and productivity assessment of a concrete bathroom unit fabricated through 3D printing and a precast approach. J. Clean. Prod. 261 , 121245 (2020).

Ngo, T. D. et al. Additive manufacturing (3D printing): a review of materials, methods, applications and challenges. Compos. Part B: Eng. 143 , 172–196 (2018).

Article   CAS   Google Scholar  

Wangler, T. et al. Digital concrete: a review. Cem. Concr. Res. 123 , 105780 (2019).

Lu, B. et al. A systematical review of 3D printable cementitious materials. Constr. Build. Mater. 207 , 477–490 (2019).

Xiao, J. et al. Large-scale 3D printing concrete technology: current status and future opportunities. Cem. Concr. Compos. 122 , 104115 (2021).

Dey, D. et al. Use of industrial waste materials for 3D printing of sustainable concrete: a review. J. Clean. Prod. 340 , 130749 (2022).

Teng, F. et al. BIM-enabled collaborative-robots 3D concrete printing to construct MiC with reinforcement. HKIE Trans. 30 , 106–115 (2023).

Vantyghem, G., De Corte, W., Shakour, E. & Amir, O. 3D printing of a post-tensioned concrete girder designed by topology optimization. Autom. Constr. 112 , 103084 (2020).

Bi, M. et al. Topology optimization for 3D concrete printing with various manufacturing constraints. Addit. Manuf. 57 , 102982 (2022).

Google Scholar  

Weng, Y. et al. Extracting BIM information for lattice toolpath planning in digital concrete printing with developed dynamo script: a case study. J. Comput. Civ. Eng. 35 , 05021001 (2021).

Breseghello, L. & Naboni, R. Toolpath-based design for 3D concrete printing of carbon-efficient architectural structures. Addit. Manuf. 56 , 102872 (2022).

CAS   Google Scholar  

Adaloudis, M. & Roca, J. B. Sustainability tradeoffs in the adoption of 3D Concrete Printing in the construction industry. J. Clean. Prod. 307 , 127201 (2021).

Tinoco, M. P. et al. Life cycle assessment (LCA) and environmental sustainability of cementitious materials for 3D concrete printing: a systematic literature review. J. Build. Eng. 52 , 104456 (2022).

Chen, Y. et al. A review of printing strategies, sustainable cementitious materials and characterization methods in the context of extrusion-based 3D concrete printing. J. Build. Eng. 45 , 103599 (2022).

Lu, B., Li, M., Wong, T. N. & Qian, S. Effect of printing parameters on material distribution in spray-based 3D concrete printing (S-3DCP). Autom. Constr. 124 , 103570 (2021).

Ford, S. & Despeisse, M. Additive manufacturing and sustainability: an exploratory study of the advantages and challenges. J. Clean. Prod. 137 , 1573–1587 (2016).

Liu, J. et al. 3D-printed concrete with recycled glass: effect of glass gradation on flexural strength and microstructure. Constr. Build. Mater. 314 , 125561 (2022).

Wu, Y. et al. Study on the rheology and buildability of 3D printed concrete with recycled coarse aggregates. J. Build. Eng. 42 , 103030 (2021).

Oosthuizen, J. D., Babafemi, A. J. & Walls, R. S. 3D-printed recycled plastic eco-aggregate (Resin8) concrete. Constr. Build. Mater. 408 , 133712 (2023).

Valente, M., Sambucci, M., Chougan, M. & Ghaffar, S. H. Composite alkali-activated materials with waste tire rubber designed for additive manufacturing: an eco-sustainable and energy saving approach. J. Mater. Res. Technol. 24 , 3098–3117 (2023).

Liu, C. et al. Influence of hydroxypropyl methylcellulose and silica fume on stability, rheological properties, and printability of 3D printing foam concrete. Cem. Concr. Compos. 122 , 104158 (2021).

Tinoco, M. Pimentel et al. The use of rice husk particles to adjust the rheological properties of 3D printable cementitious composites through water sorption. Constr. Build. Mater. 365 , 130046 (2023).

Ye, J. et al. Development of 3D printable engineered cementitious composites with incineration bottom ash (IBA) for sustainable and digital construction. J. Clean. Prod. 422 , 138639 (2023).

Ibrahim, K. A., van Zijl, G. P. A. G. & Babafemi, A. J. Influence of limestone calcined clay cement on properties of 3D printed concrete for sustainable construction. J. Build. Eng. 69 , 106186 (2023).

Chen, Y. et al. 3D printing of calcined clay-limestone-based cementitious materials. Cem. Concr. Res. 149 , 106553 (2021).

Qian, H. et al. Synergistic effect of EVA copolymer and sodium desulfurization ash on the printing performance of high volume blast furnace slag mixtures. Addit. Manuf. 46 , 102183 (2021).

Bhattacherjee, S. et al. Sustainable materials for 3D concrete printing. Cem. Concr. Compos. 122 , 104156 (2021).

Liu, J., Setunge, S. & Tran, P. 3D concrete printing with cement-coated recycled crumb rubber: compressive and microstructural properties. Constr. Build. Mater. 347 , 128507 (2022).

Ding, T., Xiao, J., Zou, S. & Wang, Y. Hardened properties of layered 3D printed concrete with recycled sand. Cem. Concr. Compos. 113 , 103724 (2020).

Liu, H. et al. Hardened properties of 3D printed concrete with recycled coarse aggregate. Cem. Concr. Res. 159 , 106868 (2022).

H.K.E.P. Department. Hong Kong Solid Waste Monitoring Report Waste Statistics 2022 (2022).

H.K.E.P. Department. Waste Blueprint for Hong Kong 2035 (2021).

Ahmed, G. H., Askandar, N. H. & Jumaa, G. B. A review of largescale 3DCP: material characteristics, mix design, printing process, and reinforcement strategies. Structures 43 , 508–532 (2022).

Christen, H., van Zijl, G. & de Villiers, W. The incorporation of recycled brick aggregate in 3D printed concrete. Clean. Mater. 4 , 100090 (2022).

Sambucci, M., Biblioteca, I. & Valente, M. Life Cycle Assessment (LCA) of 3D concrete printing and casting processes for cementitious materials incorporating ground waste tire rubber. Recycling 8 , 15 (2023).

Skibicki, S. et al. The effect of using recycled PET aggregates on mechanical and durability properties of 3D printed mortar. Constr. Build. Mater. 335 , 127443 (2022).

Weng, Y., Li, M., Tan, M. J. & Qian, S. Design 3D printing cementitious materials via Fuller Thompson theory and Marson-Percy model. Constr. Build. Mater. 163 , 600–610 (2018).

Nerella, V. N. et al. Inline quantification of extrudability of cementitious materials for digital construction. Cem. Concr. Compos. 95 , 260–270 (2019).

Wu, Y. et al. 3D printed concrete with recycled sand: pore structures and triaxial compression properties. Cem. Concr. Compos. 139 , 105048 (2023).

Ting, G. H. A., Tay, Y. W. D., Qian, Y. & Tan, M. J. Utilization of recycled glass for 3D concrete printing: rheological and mechanical properties. J. Mater. Cycles Waste Manag. 21 , 994–1003 (2019).

Zou, M. et al. Evaluation and control of printability and rheological properties of 3D-printed rubberized concrete. J. Build. Eng. 80 , 107988 (2023).

Ding, T., Xiao, J. & Tam, V. W. Y. A closed-loop life cycle assessment of recycled aggregate concrete utilization in China. Waste Manag. 56 , 367–375 (2016).

Article   PubMed   Google Scholar  

Han, Y., Yang, Z., Ding, T. & Xiao, J. Environmental and economic assessment on 3D printed buildings with recycled concrete. J. Clean. Prod. 278 , 123884 (2021).

Shen, W. et al. Quantifying CO 2 emissions from China’s cement industry. Renew. Sustain. Energy Rev. 50 , 1004–1012 (2015).

Weng, Y. et al. Feasibility study on sustainable magnesium potassium phosphate cement paste for 3D printing. Constr. Build. Mater. 221 , 595–603 (2019).

Gardner, L. J. et al. Characterisation of magnesium potassium phosphate cements blended with fly ash and ground granulated blast furnace slag. Cem. Concr. Res. 74 , 78–87 (2015).

Tangstad, M. in Handbook of Ferroalloys (ed. Gasik, M.) 179–220 (Butterworth-Heinemann, 2013).

Lucen, H. et al. The synergistic effect of greenhouse gas CO 2 and silica fume on the properties of 3D printed mortar. Compos. Part B: Eng. 271 , 111188 (2024).

Chen, Y. et al. Limestone and calcined clay-based sustainable cementitious materials for 3D concrete printing: a fundamental study of extrudability and early-age strength development. Appl. Sci. 9 , 1809 (2019).

Weng, Y. et al. Empirical models to predict rheological properties of fiber reinforced cementitious composites for 3D printing. Constr. Build. Mater. 189 , 676–685 (2018).

Zhao, Y. et al. Development of low-carbon materials from GGBS and clay brick powder for 3D concrete printing. Constr. Build. Mater. 383 , 131232 (2023).

Xu, Z. et al. Effect of FA and GGBFS on compressive strength, rheology, and printing properties of cement-based 3D printing material. Constr. Build. Mater. 339 , 127685 (2022).

Rahul, A. V., Santhanam, M., Meena, H. & Ghani, Z. 3D printable concrete: Mixture design and test methods. Cem. Concr. Compos. 97 , 13–23 (2019).

Long, W.-J. et al. Printability and particle packing of 3D-printable limestone calcined clay cement composites. Constr. Build. Mater. 282 , 122647 (2021).

Yao, Y., Hu, M., Di Maio, F. & Cucurachi, S. Life cycle assessment of 3D printing geo‐polymer concrete: an ex‐ante study. J. Ind. Ecol. 24 , 116–127 (2020).

Liu, S. et al. A comparative study on environmental performance of 3D printing and conventional casting of concrete products with industrial wastes. Chemosphere 298 , 134310 (2022).

Article   CAS   PubMed   Google Scholar  

Gao, W. et al. The status, challenges, and future of additive manufacturing in engineering. Comput. Aided Des. 69 , 65–89 (2015).

Michell, A. G. M. The limits of economy of material in frame structures. Philos. Mag. 8 , 589–597 (1904).

Bendsoe, M. P. & Kikuchi, N. Generating optimal topologies in structural design using a homogenization method. Comput. Methods Appl. Mech. Eng. 71 , 197–224 (1988).

Lurie, K. A., Cherkaev, A. V. & Fedorov, A. V. Regularization of optimal design problems for bars and plates, part 1. J. Optim. Theory Appl. 37 , 499–522 (1982).

Suzuki, K. & Kikuchi, N. A homogenization method for shape and topology optimization. Comput. Methods Appl. Mech. Eng. 93 , 291–318 (1991).

Xie, Y. M. & Steven, G. P. A simple evolutionary procedure for structural optimization. Comput. Struct. 49 , 885–896 (1993).

Querin, O. M., Steven, G. P. & Xie, Y. M. Evolutionary structural optimisation (ESO) using a bidirectional algorithm. Eng. Comput. 15 , 1031–1048 (1998).

Zhuang, Z., Xie, Y. M., Li, Q. & Zhou, S. Body-fitted bi-directional evolutionary structural optimization using nonlinear diffusion regularization. Comput. Methods Appl. Mech. Eng. 396 , 115114 (2022).

Sethian, J. A. & Wiegmann, A. Structural boundary design via level set and immersed interface methods. J. Comput. Phys. 163 , 489–528 (2000).

Allaire, G., Jouve, F. & Toader, A.-M. A level set method for shape optimization. C. R. Math. 334 , 1125–1130 (2002).

Bendsoe, M. P. Optimal shape design as a material distribution problem. Struct. Optim. 1 , 193–202 (1989).

Sigmund, O. Materials with prescribed constitutive parameters: an inverse homogenization problem. Int. J. Solids Struct. 31 , 2313–2329 (1994).

Sigmund, O. On the design of compliant mechanisms using topology optimization. Mech. Struct. Mach. 25 , 493–524 (1997).

Sigmund, O. A 99 line topology optimization code written in Matlab. Struct. Multidiscip. Optim. 21 , 120–127 (2001).

Xie, Y. M. & Steven, G. P. Evolutionary Structural Optimization (Springer-Verlag, 1997).

Xie, Y. M. & Steven, G. P. Evolutionary structural optimization for dynamic problems. Comput. Struct. 58 , 1067–1073 (1996).

Yang, X. Y., Xie, Y. M., Steven, G. & Querin, O. Bidirectional evolutionary method for stiffness optimization. AIAA J. 37 , 1483–1488 (1999).

Osher, S. & Sethian, J. A. Fronts propagating with curvature-dependent speed: Algorithms based on Hamilton-Jacobi formulations. J. Comput. Phys. 79 , 12–49 (1988).

Vese, L. A. & Chan, T. F. A multiphase level set framework for image segmentation using the mumford and Shah model. Int. J. Comput. Vis. 50 , 271–293 (2002).

Wang, M. Y., Wang, X. & Guo, D. A level set method for structural topology optimization. Comput. Methods Appl. Mech. Eng. 192 , 227–246 (2003).

Wang, M. Y. & Wang, X. “Color” level sets: a multi-phase method for structural topology optimization with multiple materials. Comput. Methods Appl. Mech. Eng. 193 , 469–496 (2004).

Otomori, M., Yamada, T., Izui, K. & Nishiwaki, S. Matlab code for a level set-based topology optimization method using a reaction diffusion equation. Struct. Multidiscip. Optim. 51 , 1159–1172 (2014).

Huang, X. On smooth or 0/1 designs of the fixed-mesh element-based topology optimization. Adv. Eng. Softw. 151 , 102942 (2021).

Zhuang, Z. et al. A node moving-based structural topology optimization method in the body-fitted mesh. Comput. Methods Appl. Mech. Eng. 419 , 116663 (2024).

Bi, M., Tran, P. & Xie, Y. M. Topology optimization of 3D continuum structures under geometric self-supporting constraint. Addit. Manuf. 36 , 101422 (2020).

Xie, Y. M. Generalized topology optimization for architectural design. Architect. Intell. 1 , 1–11 (2022).

Liu, Y. et al. Reducing the number of different faces in free-form surface approximations through clustering and optimization. Comput. Aided Des. 166 , 103633 (2024).

Zhao, Z.-L., Zhou, S., Feng, X.-Q. & Xie, Y. M. Morphological optimization of scorpion telson. J. Mech. Phys. Solids 135 , 103773 (2020).

Cai, K., Chen, B. S. & Zhang, H. W. Topology optimization of continuum structures based on a new bionics method. Int. J. Computat. Methods Eng. Sci. Mech. 8 , 233–242 (2007).

Zhu, J., Zhang, W. & Xia, L. Topology optimization in aircraft and aerospace structures design. Arch. Comput. Methods Eng. 23 , 595–622 (2016).

Leader, M. K., Chin, T. W. & Kennedy, G. High resolution topology optimization of aerospace structures with stress and frequency constraints, In Proc. 2018 Multidisciplinary Analysis and Optimization Conference, American Institute of Aeronautics and Astronautics (2018).

Menna, C. et al. Opportunities and challenges for structural engineering of digitally fabricated concrete. Cem. Concr. Res. 133 , 106079 (2020).

Chen, Y., Zhou, C. & Lao, J. A layerless additive manufacturing process based on CNC accumulation. Rapid Prototyp. J. 17 , 218–227 (2011).

Pan, Y., Zhou, C., Chen, Y. & Partanen, J. Multi-tool and multi-axis CNC Accumulation for fabricating conformal features on curved surfaces. J. Manuf. Sci. Eng. 136 , 031007 (2014).

Ooms, T. et al. Third RILEM International Conference on Concrete and Digital Fabrication 37–42 (Springer International Publishing, 2022).

Asprone, D., Auricchio, F., Menna, C. & Mercuri, V. 3D printing of reinforced concrete elements: Technology and design approach. Constr. Build. Mater. 165 , 218–231 (2018).

Gebhard, L. et al. Structural behaviour of 3D printed concrete beams with various reinforcement strategies. Eng. Struct. 240 , 112380 (2021).

Martens, P., Mathot, M., Bos, F. & Coenders, J. High Tech Concrete: Where Technology and Engineering Meet 301–309 (Springer International Publishing, 2018).

Ahmed, G. H. A review of “3D concrete printing”: materials and process characterization, economic considerations and environmental sustainability. J. Build. Eng. 66 , 105863 (2023).

Tay, Y. W. D., Lim, J. H., Li, M. & Tan, M. J. Creating functionally graded concrete materials with varying 3D printing parameters. Virtual Phys. Prototyp. 17 , 662–681 (2022).

Li, Y. et al. FloatArch: a cable-supported, unreinforced, and re-assemblable 3D-printed concrete structure designed using multi-material topology optimization. Addit. Manuf. 81 , 104012 (2024).

Yang, W., Wang, L., Ma, G. & Feng, P. An integrated method of topological optimization and path design for 3D concrete printing. Eng. Struct. 291 , 116435 (2023).

Mechtcherine, V. et al. Extrusion-based additive manufacturing with cement-based materials—production steps, processes, and their underlying physics: A review. Cem. Concr. Res. 132 , 106037 (2020).

Tu, H. et al. Recent advancements and future trends in 3D concrete printing using waste materials. Dev. Built Environ. 16 , 100187 (2023).

Heywood, K. & Nicholas, P. Sustainability and 3D concrete printing: identifying a need for a more holistic approach to assessing environmental impacts. Architect. Intell. 2 , 12 (2023).

Wang, L., Jiang, H., Li, Z. & Ma, G. Mechanical behaviors of 3D printed lightweight concrete structure with hollow section. Arch. Civ. Mech. Eng. 20 , 16 (2020).

Geng, Z., Pan, H., Zuo, W. & She, W. Functionally graded lightweight cement-based composites with outstanding mechanical performances via additive manufacturing. Addit. Manuf. 56 , 102911 (2022).

Xia, L. et al. Integrated lightweight design method via structural optimization and path planning for material extrusion. Addit. Manuf. 62 , 103387 (2023).

Jin, Y.-a et al. Optimization of tool-path generation for material extrusion-based additive manufacturing technology. Addit. Manuf. 1-4 , 32–47 (2014).

Jin, Y. et al. An optimization approach for path planning of high-quality and uniform additive manufacturing. Int. J. Adv. Manuf. Technol. 92 , 651–662 (2017).

Ding, D., Pan, Z., Cuiuri, D. & Li, H. A practical path planning methodology for wire and arc additive manufacturing of thin-walled structures. Robot. Comput. Integr. Manuf. 34 , 8–19 (2015).

Sales, E., Kwok, T.-H. & Chen, Y. Function-aware slicing using principal stress line for toolpath planning in additive manufacturing. J. Manuf. Process. 64 , 1420–1433 (2021).

Chakraborty, D., Reddy, B. & Choudhury, A. Extruder path generation for Curved Layer Fused Deposition Modeling. Comput. Aided Des. 40 , 235–243 (2008).

Jiang, J. & Ma, Y. Path planning strategies to optimize accuracy, quality, build time and material use in additive manufacturing: a review. Micromachines 11 , 633 (2020).

Article   PubMed   PubMed Central   Google Scholar  

Giberti, H., Sbaglia, L. & Urgo, M. A path planning algorithm for industrial processes under velocity constraints with an application to additive manufacturing. J. Manuf. Syst. 43 , 160–167 (2017).

Jin, Y. et al. A non-retraction path planning approach for extrusion-based additive manufacturing. Robot. Comput. Integr. Manuf. 48 , 132–144 (2017).

Wang, T. et al. Load-dependent path planning method for 3D printing of continuous fiber reinforced plastics. Compos. Part A: Appl. Sci. Manuf. 140 , 106181 (2021).

Chen, X., Fang, G., Liao, W.-H. & Wang, C. C. L. Field-based toolpath generation for 3D printing continuous fibre reinforced thermoplastic composites. Addit. Manuf. 49 , 102470 (2022).

Zhou, W., McGee, W., Gökçe, H. S. & Li, V. C. A bio-inspired solution to alleviate anisotropy of 3D printed engineered cementitious composites (3DP-ECC): Knitting/tilting filaments. Autom. Constr. 155 , 105051 (2023).

Anton, A. et al. A 3D concrete printing prefabrication platform for bespoke columns. Autom. Constr. 122 , 103467 (2021).

Dörrie, R. et al. Automated force-flow-oriented reinforcement integration for Shotcrete 3D Printing. Autom. Constr. 155 , 105075 (2023).

Breseghello, L., Hajikarimian, H., Jørgensen, H. B. & Naboni, R. 3DLightBeam+. Design, simulation, and testing of carbon-efficient reinforced 3D concrete printed beams. Eng. Struct. 292 , 116511 (2023).

Moini, M. et al. Additive manufacturing and performance of architectured cement-based materials. Adv. Mater. 30 , 1802123 (2018).

Lin, Z. et al. Tool path generation for multi-axis freeform surface finishing with the LKH TSP solver. Comput. Aided Des. 69 , 51–61 (2015).

Zareiyan, B. & Khoshnevis, B. Effects of interlocking on interlayer adhesion and strength of structures in 3D printing of concrete. Autom. Constr. 83 , 212–221 (2017).

Bi, M. et al. Continuous contour-zigzag hybrid toolpath for large format additive manufacturing. Addit. Manuf. 55 , 102822 (2022).

Vispute, M., Kumar, N., Taufik, M. & Jain, P. K. Improving surface finish of extrusion based additive manufactured parts using novel triangle based toolpath approach. Int. J. Interact. Des. Manuf. 18 , 433–452 (2024).

Jensen, M. L. et al. Toolpath strategies for 5DOF and 6DOF extrusion-based additive manufacturing, Appl. Sci. 9 , 4168 (2019).

Li, C. L. A geometric approach to boundary-conformed toolpath generation. Comput. Aided Des. 39 , 941–952 (2007).

Breseghello, L. & Naboni, R. Adaptive toolpath: enhanced design and process control for robotic 3DCP. In International Conference on Computer-Aided Architectural Design Futures 301–316 (2022).

Liu, W., Chen, L., Mai, G. & Song, L. Toolpath planning for additive manufacturing using sliced model decomposition and metaheuristic algorithms. Adv. Eng. Softw. 149 , 102906 (2020).

Yang, W. et al. An integrated topology optimization method including manufacturing constraints for 3D printed fiber-reinforced concrete structures. Mater. Lett. 355 , 135442 (2024).

Lin, S. et al. A maze-like path generation scheme for fused deposition modeling. Int. J. Adv. Manuf. Technol. 104 , 1509–1519 (2019).

Jin, G. Q., Li, W. D., Gao, L. & Popplewell, K. A hybrid and adaptive tool-path generation approach of rapid prototyping and manufacturing for biomedical models. Comput. Ind. 64 , 336–349 (2013).

Moini, R. Perspectives in architected infrastructure materials. RILEM Tech. Lett. 8 , 125–140 (2024).

Xia, L., Lin, S. & Ma, G. Stress-based tool-path planning methodology for fused filament fabrication. Addit. Manuf. 32 , 101020 (2020).

Xia, L. et al. Globally continuous hybrid path for extrusion-based additive manufacturing. Autom. Constr. 137 , 104175 (2022).

Li, N. et al. Path-designed 3D printing for topological optimized continuous carbon fibre reinforced composite structures. Compos. Part B: Eng. 182 , 107612 (2020).

Liu, J., Ma, Y., Qureshi, A. J. & Ahmad, D. R. Light-weight shape and topology optimization with hybrid deposition path planning for FDM parts. Int. J. Adv. Manuf. Technol. 97 , 1123–1135 (2018).

Ye, J. et al. Feasibility of using ultra-high ductile concrete to print self-reinforced hollow structures. in Proc. Third RILEM International Conference on Concrete and Digital Fabrication 133–138 (2022).

Jin, G. Q., Li, W. D., Tsai, C. F. & Wang, L. Adaptive tool-path generation of rapid prototyping for complex product models. J. Manuf. Syst. 30 , 154–164 (2011).

Jin, Y.-A., He, Y., Xue, G.-H. & Fu, J.-Z. A parallel-based path generation method for fused deposition modeling. Int. J. Adv. Manuf. Technol. 77 , 927–937 (2015).

Roberts, H. & Petticrew, M. Systematic Reviews in the Social Sciences: A Practical Guide (Wiley, 2006).

Glowinski, R. Trends and Applications of Pure Mathematics to Mechanics 96–145 (Springer Berlin Heidelberg, 1984).

Kikuchi, N., Chung, K. Y., Torigaki, T. & Taylor, J. E. Computer Methods in Applied Mechanics and Engineering 139–169 (1986).

Andreassen, E. et al. Efficient topology optimization in MATLAB using 88 lines of code. Struct. Multidiscip. Optim. 43 , 1–16 (2011).

Ferrari, F. & Sigmund, O. A new generation 99 line Matlab code for compliance topology optimization and its extension to 3D. Struct. Multidiscip. Optim. 62 , 2211–2228 (2020).

Rozvany, G. I. N., Zhou, M. & Birker, T. Generalized shape optimization without homogenization. Struct. Optim. 4 , 250–252 (1992).

Huang, X. & Xie, Y. M. Evolutionary Topology Optimization of Continuum Structures: Methods and Applications (Wiley, 2010).

Zuo, Z. H. & Xie, Y. M. A simple and compact Python code for complex 3D topology optimization. Adv. Eng. Softw. 85 , 1–11 (2015).

Huang, X., Xie, Y. M. & Burry, M. C. A new algorithm for bi-directional evolutionary structural optimization. JSME Int. J. Ser. C. Mech. Syst., Mach. Elem. Manuf. 49 , 1091–1099 (2006).

Challis, V. J. A discrete level-set topology optimization code written in Matlab. Struct. Multidiscip. Optim. 41 , 453–464 (2010).

Allaire, G., Jouve, F. & Toader, A.-M. Structural optimization using sensitivity analysis and a level-set method. J. Comput. Phys. 194 , 363–393 (2004).

Zhuang, Z., Xie, Y. M., Li, Q. & Zhou, S. A 172-line Matlab code for structural topology optimization in the body-fitted mesh. Struct. Multidiscip. Optim. 66 , 11 (2022).

Yamada, T., Izui, K., Nishiwaki, S. & Takezawa, A. A topology optimization method based on the level set method incorporating a fictitious interface energy. Comput. Methods Appl. Mech. Eng. 199 , 2876–2891 (2010).

Li, H. et al. Full-scale 3D structural topology optimization using adaptive mesh refinement based on the level-set method. Finite Elem. Anal. Des. 194 , 103561 (2021).

Zhuang, Z., Xie, Y. M. & Zhou, S. A reaction diffusion-based level set method using body-fitted mesh for structural topology optimization. Comput. Methods Appl. Mech. Eng. 381 , 113829 (2021).

Huang, X. A Matlab code of topology optimization by imposing the implicit floating projection constraint. (2022).

Huang, X. & Li, W. Three-field floating projection topology optimization of continuum structures. Comput. Methods Appl. Mech. Eng. 399 , 115444 (2022).

Zhang, X. et al. A nodal-based optimization method for the design of continuous fiber-reinforced structures. Compos. Struct. 323 , 117455 (2023).

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Acknowledgements

This project was funded by National Science and Foundation of China (52308284), Department of Science and Technology of Guangdong Province (306071352047), and Hong Kong Polytechnic University (P0038598, P0038966, P0044299, P0045796). The funder played no role in study design, data collection, analysis and interpretation of data, or the writing of this manuscript.

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Department of Building and Real Estate, The Hong Kong Polytechnic University, Hong Kong, China

Zicheng Zhuang, Fengming Xu, Junhong Ye & Yiwei Weng

Department of Civil Engineering and Transportation, South China University of Technology, Hong Kong, China

Department of Building Environment and Energy Engineering, The Hong Kong Polytechnic University, Hong Kong, China

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Z.Z., M.X., and J.Y. conducted the review and wrote the manuscript. H.N., L.J., and Y.W. made suggestions and revised the manuscript. Y.W. provided the resources and supervision. All authors read and approved the final manuscript.

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Zhuang, Z., Xu, F., Ye, J. et al. A comprehensive review of sustainable materials and toolpath optimization in 3D concrete printing. npj Mater. Sustain. 2 , 12 (2024). https://doi.org/10.1038/s44296-024-00017-9

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