Dematerialization of Concrete: Meta-Analysis of Lightweight Expanded Clay Concrete for Compressive Strength

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

·         Correctly write the chemical formula

·         In the introduction the literature on the lightweight is limited try to expand the literature and show the main parameter affect lightweight concrete.

·         Line 106 to 108 rewrite

·         Line 139 to 145 rewrite repeated

·         3.3. An Equation to Predict 28-day Compressive Strength of LECA Concrete

 

This section need a lot of work

There is no available information about the data used in developing the model what is the maximum and minimum values the mean

 

·         Line 173 to 176 R2 value of 0.59, with an adjusted R2 value of 0.57. The adjusted R2 value is considered for multiple regression analysis. Considering the heterogenous nature of concrete at

R2=0.57  is considered very low to be used to predicted the compressive strength

 

·         Line 219  For example, the maximum water amount was limited to 200 kg/m3, what is the limits in the developed equation

 

·         Line 323  “A potential reason for the 15% difference between the estimated and experimental results is that LECA used in the experiments was produced mainly for agricultural applications. Structural LECA was reported to be used in some studies, thereby affecting the prediction model”

Is this an explanation for the difference between the model and the experimental? This is doesn’t make sense

 

·         Line 336 Results presented in Figure 6 indicate that a stronger relationship, indicated by proximity to the line of equality

Where is Fig.6

·         Rewrite conclusion focusing on main points

·         Do not write the equations in the conclusion

Comments on the Quality of English Language

English language need editing 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The research focuses on predicting the compressive strength of lightweight expanded clay concrete through meta-analysis and experimental verification. The authors compile data from over 140 data points and develop a regression model to estimate the 28-day compressive strength. The experimental program validates the model's accuracy, providing a comprehensive approach to address this topic.

Comments:

1. The introduction section effectively highlights the benefits of using lightweight expanded clay aggregate (LECA) concrete in construction, setting the context for the study's significance.
2. What are the criteria used for selecting the specific studies included in the meta-analysis? It would be beneficial to provide more details on the selection process.
3. The statistical measures section (3.1) is well-explained, aiding in understanding the analysis approach. However, a brief explanation of why these specific measures were chosen would further clarify their relevance.
4. The statement "Results indicate that water absorption of LECA may be up to an order of magnitude higher compared to crushed limestone used as aggregate in concrete-making" (page 6) appears to contradict the data presented in Table 1, where the water absorption of LECA is lower than that of crushed limestone. Please clarify or address this potential discrepancy.
5. The sensitivity analysis and parameter optimization sections (3.4) provide valuable insights into the relative influence of different variables on the compressive strength prediction, enhancing the model's applicability.
6. In the experimental program (Section 4), it would be beneficial to provide more details on the specific LECA products used, as the authors mention that "LECA used in the experiments was produced mainly for agricultural applications" (page 9).
7. The authors acknowledge the segregation issue encountered during specimen preparation (Section 4.3). Discussing potential mitigation strategies or further investigation into this aspect could be valuable for future research.
8. While the comparison between predicted and experimental results (Section 5) is comprehensive, it would be interesting to explore the reasons behind the overestimation observed in the prediction model, beyond the potential influence of using non-structural LECA.
9. The equation presented in Section 3.3 is a valuable contribution, providing a practical tool for estimating the compressive strength of LECA concrete. However, it would be beneficial to discuss the equation's limitations or potential factors that may influence its accuracy.
10. In the conclusion section, the authors mention that "the equation may be adjusted by using such a coefficient, but further analysis is necessary." Could you elaborate on the potential adjustments and the need for further analysis?
11. The meta-analysis approach is commendable, as it synthesizes data from multiple studies, but could you provide insights into the potential limitations or challenges associated with this methodology?
12. While the authors acknowledge the heterogeneous nature of concrete, it would be interesting to explore how the proposed model could be adapted or extended to account for variations in material properties or environmental conditions.
13. Page 7, Section 4.2: "Mixes #11-#13" are mentioned, but the table only shows data up to Mix #10. Please clarify or provide the missing information.
14. In Figure 4, it is observed that the data points for 0.27 m³ LECA/m³ concrete are scattered and have a lower R² value compared to the data points for ≥0.36 m³ LECA/m³ concrete. Could you provide insights into the potential reasons for this difference and its implications?
15. The manuscript focuses on the compressive strength of LECA concrete, but could you comment on the potential influence of LECA on other properties, such as durability, thermal performance, or sustainability aspects?
16. While the study focuses on the 28-day compressive strength, it would be interesting to explore the model's applicability or potential modifications for predicting strength at different curing ages.
17. The authors mention that "LECA used in the experiments was produced mainly for agricultural applications." Could you discuss the potential implications of using structural LECA on the prediction model's accuracy or the need for further validation?

18.  It is suggested to take advantage of research insights: https://doi.org/10.3390/cryst12070944; https://doi.org/10.1016/j.conbuildmat.2023.132604;

19. In Section 5, the authors state that "results do not significantly deviate from the line of equality." However, in Figure 5, there appears to be a noticeable deviation for some data points. Could you clarify this statement or provide additional insights into the extent of the deviations?

 

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The paper is interesting, relevant, using meta-analysis to derive dependencies of lightweight aggregated concrete. The practical significance is obvious.

However, there are a number of remarks to the article. The most important ones are to update the data sources (they are outdated) and to structure the article.

1. Аbstract. The abstract should explain the effects that were found when building the model. Why the low-strength results were more accurate.

The abstract states that more than 140 data were processed in the model. It is necessary to specify their source - that they are different sources from 15 different researchers.

2. The paper lacks a clear structure of IMRAD. Point 1 is an introduction, but points 2 and 3 are also introductions, and point 3 should be substantially shortened due to obviousness and cite the literature where meta-analysis is used in the construction.

3. The reference list contains old sources, no more than 5 years is needed for technical literature. Give examples of the use of meta-analysis and predictive model.

4. Section 3.2 is already results.

5. Section 3.1 is again Methods. This section can be removed as it contains things that are obvious to an engineer.

6. Section 4.3 - relate to Methods, etc. Break the article into headings and sub-headings as is done in the MDPI template.

7. Conclusion. 

Line 351 - 352 it is arguable that if the authors took 140 points, this is a more reliable result than the result of a separate study. What if it looked at 142 points? There is one study, but with 160 points. That's a strange conclusion. 

Line 357-what specific assays are needed to make the equation more accurate, please explain. Why so many analyses were not enough.

Line 359 - 363, "the results for lower compressive strength concrete appear closer than the results for high strength concrete. Regarding w/b ratio, more accurate results were obtained for concrete mixtures with w/b ratios of 0.5 or higher. Mixtures containing higher amounts of LECA by volume of concrete gave more accurate results when using the prediction model." What is your explanation for these phenomena?

Overall, the meta-analysis is based on 140 data. There are 15 papers in the appendix, and these are from 2005 - 2016. This is irrelevant data, and the article focuses on material that the authors call innovative. Provide new literature on this topic, and perhaps the meta-analysis should be refined to take into account the new data.  

 

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The paper is ok after revision 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript has undergone thorough revision and is now ready to proceed to the next stage of the publication process.

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors, you never constructed the article according to the IMRAD system, which is a strict requirement of the journal. This remark is at the discretion of the editors.

You never added new research that has been done in the last 10 years in this field. It is good that once a master's thesis was written and you decided to publish it, but time has passed and technical articles require literature at least 5 years old.

 

 

Author Response

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Author Response File: Author Response.pdf

Round 3

Reviewer 3 Report

Comments and Suggestions for Authors

Dear authors, I see that the article is not done according to IMRAD. As a reviewer, I cannot ignore it, as it is a rule of MDPI. Let the editorial board decide whether to accept the article.Dear authors, I see that the article is not done according to IMRAD. As a reviewer, I cannot ignore it, as it is a rule of MDPI. Let the editorial board decide whether to accept the article.

Author Response

Please see the attachment.

Author Response File: Author Response.docx