Post-Fire Mechanical Properties of Concrete Incorporating Waste EPS (Styrofoam) as Aggregate Replacement

Round 1

Reviewer 1 Report

The research is devoted to disposed of Styrofoam (Astropol) as a replacement for fine aggregate in concrete structures.  The result showed that post-fire compressive strength of concrete containing different ratios of the EPS (Astropol) increases compared to the conventional concrete.

This study investigates the fresh concrete properties with and without the addition of EPS (Astropol) and hardened concrete mechanical properties before and post-firing. A study is performed to find solutions to reduce, recycle, and reuse those wastes and reduce environmental impact.

 

Comments and questions:

1.      What does mean the phrase “The amount of concrete in each batch was increased by 10 % for the planned specimens”. Is this concrete increasing provided by the increasing amount of EPS waste?   line 166

2.      There are lack the ground waste (EPS and Deep sea sand) particle size distributions. It should be added.

3.      It isn’t clear how was calculated amount of EPS waste in %. “The EPS waste contents were 15%, 25%, and 50% by weight of the fine aggregate” (line 158-159). As an example,  for 25% EPS weight of EPS is 0.547 g, and the fine aggregate – 848.66 g. The authors need to explain the method of calculation.

4.      Could you hypothesize why adding more EPS improves split tensile strength?

 

5.      There is a lack of quantitative evaluation (in %) of the influence of adding EPS on the strength properties of concrete in the Conclusions. It should be added.

Author Response

Reviewer #1

Comments and questions:

1. What does mean the phrase “The amount of concrete in each batch was increased by 10 % for the planned specimens”. Is this concrete increasing provided by the increasing amount of EPS waste?   line 166

Respond:

1. Thanks for your comments, in order to guarantee the sufficient amount of concrete to prepare the samples the exact volume of concrete required as per the volume of the molds is increased by 10% to be in safe side.

 

2. There are lack the ground waste (EPS and Deep sea sand) particle size distributions. It should be added.

Respond:

2.  

Figure 1 Prticle size distribution of EPS & Deep sea sand.(Rezaie et al., 2022)

Refference : Rezaie Soufi, Ghazal, and Reza Jamshidi Chenari. "DEM model calibration and contact force network analysis of sand-EPS (rigid-soft) granular system subjected to one-dimensional compression." Granular Matter 24, no. 4 (2022): 99.

3. It isn’t clear how was calculated amount of EPS waste in %. “The EPS waste contents were 15%, 25%, and 50% by weight of the fine aggregate” (line 158-159). As an example, for 25% EPS weight of EPS is 0.547 g, and the fine aggregate – 848.66 g. The authors need to explain the method of calculation.

Respond:

3. The density of the EPS was measured and the replacement was done by weight of fine aggregate. Since the density of fine aggregate is incomparably greater than the density of EPS, the specified the weight in each percentage is taken and specifically converted to volume at each replacement level. The values shown in the volumetric mix table for EPS are volume converted to weight in gm.
4. Could you hypothesize why adding more EPS improves split tensile strength?

Respond:

4.The addition of EPS beads increases the porosity of the concrete, which allows for better distribution of stress and strain during loading. This results in a more uniform distribution of forces and reduces the likelihood of cracks forming. Also EPS beads are lightweight, which reduces the overall weight of the concrete mix. This can result in a reduction in internal stresses and strains, leading to improved split tensile strength. The addition of EPS beads can as well improve the workability of the concrete mix, making it easier to handle and place. This can result in a more uniform distribution of forces during loading, leading to improved split tensile strength. Overall, these factors may contribute to an improvement in split tensile strength when adding more EPS expanded polystyrene beads to concrete mixes.

 

5. There is a lack of quantitative evaluation (in %) of the influence of adding EPS on the strength properties of concrete in the Conclusions. It should be added.

Respond:

5.The quantitave evaluation is added in the conclusion.

 

Author Response File: Author Response.docx

Reviewer 2 Report

Research article (Titled: Post-Fire Mechanical Properties of Concrete Incorporating  Waste EPS (Styrofoam) as Aggregate Replacement) by Ilham I. Mohammed and co-workers submitted CivilEng, MDPI dealing with sustainable application of  Styrofoam waste as building materials is innovative and appreciable. The research article is well written and full of experimental data. Though several works akin to the same have been published, I strongly recommend a positive decision about this paper. Following improvement may be beneficial for the readers

1.       As compared to length & data in manuscript, abstract is lengthy

2.       Introduction is not supported with proper references

3.       Extensive thermo-mechanical characterization is needed.

4.       More information about intensity of fire, heating rate, crack propagation etc. are lacking in the research paper.

5.       The background in Figure 2-3 is annoying.

6.        Please add more explanations in the Section, 3.2, 3.4 and 3.5.

7.       UTM results in the form of a bar chart will be more valuable . 

Author Response

Reviewer #2

Research article (Titled: Post-Fire Mechanical Properties of Concrete Incorporating Waste EPS (Styrofoam) as Aggregate Replacement) by Ilham I. Mohammed and co-workers submitted CivilEng, MDPI dealing with sustainable application of Styrofoam waste as building materials is innovative and appreciable. The research article is well written and full of experimental data. Though several works akin to the same have been published, I strongly recommend a positive decision about this paper. Following improvement may be beneficial for the readers

1. As compared to length & data in manuscript, abstract is lengthy

Respond:

1. Necessary reduction in the abstract length has been done.

 

2. Introduction is not supported with proper references

Respond:

2. Proper references have been cited.
3. Extensive thermo-mechanical characterization is needed.

Respond:

3. In order to have extensive thermo-mechanical properties more tests needs to be done and this is time consuming, for the upcoming researches definitely we will try to provide a thorough understanding on the thermo-mechanical properties of concrete incorporating EPS after burning process.
4. More information about intensity of fire, heating rate, crack propagation etc. are lacking in the research paper.

Respond:

4. All the information available on the intensity of fire, heating rate and failure pattern due to the burning process have been mentioned.

 

5. The background in Figure 2-3 is annoying.

Respond:

5. The backgrounds in the figures are changed.
6. Please add more explanations in the Section, 3.2, 3.4 and 3.5.

Respond:

6. More explanation is added in the sections mentioned..
7. UTM results in the form of a bar chart will be more valuable . 

Respond:

7. sure, we are fixed all requirements.

 

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors:

 

GENERAL COMMENT ON THE USE OF THE ENGLISH LANGUAGE

The English language of the paper should be carefully checked and revised where necessary to improve its readability. Moreover, often all over the text, improper use of round parentheses and semicolons is observed and should be amended.

 

ABSTRACT

- The sentence “some types of decorative materials become rare used them in decoration purposes such as Styrofoam” in lines 12-13 should be rephrased for clarity.

- The compressive strength values and percentages of recycled aggregates reported in lines 21-22 do not help to understand the best performance declared compared to the conventional concrete material. The sentence should be rephrased for clarity.

 

1. INTRODUCTION

- In the reviewer’s opinion, the introduction should follow a more holistic approach. The authors should mention the vast research available in the technical literature on the characterisation and modelling of the compressive behaviour of normal-strength and high-strength concrete cast with traditional aggregates (e.g. 10.1016/j.ijimpeng.2018.11.003; 10.1016/j.jobe.2022.105812) and mark the primary limits and advantages of using these materials in new RC or hybrid framed structures (e.g. 10.3389/fbuil.2019.00042; 10.1016/j.engstruct.2014.02.029; 10.3390/buildings13010037). They should also cite the problem of existing structures that need to be retrofitted by strengthening techniques (e.g. 10.1016/j.conbuildmat.2018.12.144; 10.7712/120119.6987.19726; 10.7712/120119.6978.18647) and suggest the possible interactions between the new proposed material, its long-term mechanical performance and the possibility of being reinforced with traditional or more innovative strengthening systems. Finally, in the specific focus of the study, some other very recent papers could be cited as a reference to the analysis, testing and modelling of concrete with plastic aggregates (e.g. 10.1016/j.conbuildmat.2022.130279; 10.1016/j.conbuildmat.2023.130414; 1-0.1016/j.clet.2023.100600).

- The authors should improve the quality of the sentences, especially in lines 119-123 (also remove semicolon “;” where unnecessary).

 

2. MATERIALS AND METHODS

How many specimens for every EPS percentage? Please detail.

 

2.4. FRESH CONCRETE TESTS

In this section, the authors only mention the reference codes used for performing the tests. It is suggested to briefly describe the testing procedure and methods provided by those codes. Moreover, some figures could be added to represent the executed tests.

 

3.1. COMPACTION FACTOR TEST

Further comments should be proposed to the reader for discussing Figure 6. In particular, the authors should explain the higher value of the compaction factor of specimens with 50% of EPS content, compared to the smaller values of the factor obtained in the specimens with 15% and 25% of EPS aggregates.

Moreover, it should also be detailed if the results in Figure 6 represent the average value obtained from several specimens with the same features.

 

3.2 SLUMP-TEST

Further comments should be proposed to the reader for discussing Figure 7. In particular, the authors should explain the higher slump value of specimens with 50% of EPS content, compared to the smaller values obtained in the specimens with 15% and 25% of EPS aggregates.

Moreover, it should also be detailed if the results in Figure 7 represent the average value obtained from several specimens with the same features.

 

3.4. COMPRESSIVE STRENGTH

A comment on the correlation between the density and compressive strength of both normal and burned specimens should be added.

Moreover, the reduction of the compressive strength in burned specimens proves to be very critical: comments should be provided on the mechanical effectiveness of the burned concrete and suggestions should be given on the possibility of enhancing these critical mechanical properties with some strengthening interventions.

 

3.5. SPLITTING TENSILE STRENGTH

It is not clear how Figure 10 represents the burned specimens after the compressive and splitting test. Maybe, it would be more effective to show one figure with one of the specimens into the testing machine used for the compression tests and its crack pattern after that, and a different figure reporting one specimen into the testing machine adopted for the execution of the splitting tests and the resulting failure pattern.

 

CONCLUSIONS

How many specimens have been tested? 32 specimens, as declared in the Conclusions (line 287) or 36 samples, as reported in Materials and Methods (line 131)?

 

The conclusions should also include some critical comments on the resulting mechanical performance and tools to improve the protection of this sustainable material from the critical effects of high temperature and fire.

Author Response

Reviewer #3

GENERAL COMMENT ON THE USE OF THE ENGLISH LANGUAGE

The English language of the paper should be carefully checked and revised where necessary to improve its readability. Moreover, often all over the text, improper use of round parentheses and semicolons is observed and should be amended.

 Respond:

Many thanks for the reviewers’ comments, we followed the reviewer’s comments and revised the whole manuscript. The English language has been checked and revised carefully.

ABSTRACT

- The sentence “some types of decorative materials become rare used them in decoration purposes such as Styrofoam” in lines 12-13 should be rephrased for clarity.

Respond:

Many thanks for the reviewers comment, we have fixed that. The sentence from the abstract has been rephrased and now it can be said it is clear well enough.

 

- The compressive strength values and percentages of recycled aggregates reported in lines 21-22 do not help to understand the best performance declared compared to the conventional concrete material. The sentence should be rephrased for clarity.

 Respond:

We have fixed the entire of the paper. Thanks for your notes. The authors are appreciating the suggestion to have a more holistic approach in the introduction, the mentioned studies that have been suggested by the reviewer are checked and they have been found that they are far away from been cited or mentioned inside this version of the paper.

1. INTRODUCTION

- In the reviewer’s opinion, the introduction should follow a more holistic approach. The authors should mention the vast research available in the technical literature on the characterisation and modelling of the compressive behaviour of normal-strength and high-strength concrete cast with traditional aggregates (e.g. 10.1016/j.ijimpeng.2018.11.003; 10.1016/j.jobe.2022.105812) and mark the primary limits and advantages of using these materials in new RC or hybrid framed structures (e.g. 10.3389/fbuil.2019.00042; 10.1016/j.engstruct.2014.02.029; 10.3390/buildings13010037). They should also cite the problem of existing structures that need to be retrofitted by strengthening techniques (e.g. 10.1016/j.conbuildmat.2018.12.144; 10.7712/120119.6978.18647) and suggest the possible interactions between the new proposed material, its long-term mechanical performance and the possibility of being reinforced with traditional or more innovative strengthening systems. Finally, in the specific focus of the study, some other very recent papers could be cited as a reference to the analysis, testing and modelling of concrete with plastic aggregates (e.g. 10.1016/j.conbuildmat.2022.130279; 10.1016/j.conbuildmat.2023.130414; 1-0.1016/j.clet.2023.100600).

Respond:

Sure, we have added the required studies into the paper. Please check from Line 39-48.

- The authors should improve the quality of the sentences, especially in lines 119-123 (also remove semicolon “;” where unnecessary).

Respond:

Sure, we have fixed all necessary problem with language and grammar problem, which is one of the author based in English country. The quality of the sentences in the lines 119-123 has been improved.

 

2. MATERIALS AND METHODS

How many specimens for every EPS percentage? Please detail.

Respond:

For each EPS percentage 3 samples have been prepared and the results are the average of three samples. Placed inside the text.

 

2.4. FRESH CONCRETE TESTS

In this section, the authors only mention the reference codes used for performing the tests. It is suggested to briefly describe the testing procedure and methods provided by those codes. Moreover, some figures could be added to represent the executed tests.

 Respond:

Regarding the fresh properties tests; in order not to extend the length of the text and since the when mentioning the standard code the procedure is the same, which is why the procedure has not been mentioned here.

 

3.1. COMPACTION FACTOR TEST

Further comments should be proposed to the reader for discussing Figure 6. In particular, the authors should explain the higher value of the compaction factor of specimens with 50% of EPS content, compared to the smaller values of the factor obtained in the specimens with 15% and 25% of EPS aggregates.

Moreover, it should also be detailed if the results in Figure 6 represent the average value obtained from several specimens with the same features.

 Respond:

For the compaction factor test results, further comments were added to the text.

3.2 SLUMP-TEST

Further comments should be proposed to the reader for discussing Figure 7. In particular, the authors should explain the higher slump value of specimens with 50% of EPS content, compared to the smaller values obtained in the specimens with 15% and 25% of EPS aggregates.

Moreover, it should also be detailed if the results in Figure 7 represent the average value obtained from several specimens with the same features.

 Respond:

Further comment regarding the slump test results added to the text.

 

 

3.4. COMPRESSIVE STRENGTH

A comment on the correlation between the density and compressive strength of both normal and burned specimens should be added.

Moreover, the reduction of the compressive strength in burned specimens proves to be very critical: comments should be provided on the mechanical effectiveness of the burned concrete and suggestions should be given on the possibility of enhancing these critical mechanical properties with some strengthening interventions.

 Respond:

Regarding the figure which shows the specimens after testing the compressive strength and splitting tensile strength, unfortunately the photos of the specimen inside the testing machine could not be found.

 

3.5. SPLITTING TENSILE STRENGTH

It is not clear how Figure 10 represents the burned specimens after the compressive and splitting test. Maybe, it would be more effective to show one figure with one of the specimens into the testing machine used for the compression tests and its crack pattern after that, and a different figure reporting one specimen into the testing machine adopted for the execution of the splitting tests and the resulting failure pattern.

  Respond:

The specimen numbers have been corrected inside the text.

CONCLUSIONS

How many specimens have been tested? 32 specimens, as declared in the Conclusions (line 287) or 36 samples, as reported in Materials and Methods (line 131)?

 

The conclusions should also include some critical comments on the resulting mechanical performance and tools to improve the protection of this sustainable material from the critical effects of high temperature and fire.

 Respond:

Some comments were added as recommendations for future research.

 

 

 

Author Response File: Author Response.docx