Sustainable Foam Concrete Materials Utilizing Mineral Fibers Recovered from Industrial Waste

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

（1） Improve clarity and flow of English.
（2）Expand discussion on mechanisms behind material improvements.
（3） Address scalability and industrial applicability.
（4） Ensure all figures/tables are fully labeled.

（5）The conclusion part is too long, there is no summary and concision, many of them are the replication of the results part

（6）Mechanism interpretation and enhancement: In the discussion section (e.g., Section 3.1), it is suggested to add a schematic diagram of fiber-polymer synergistic mechanism, with arrows indicating the specific process of polymer film wrapping fibers and filling microcracks, so as to make up for the shortcomings of static SEM image display.

（7）Data presentation guidelines: All charts may be uniformly add error bars (such as for strength values in Table 9-11) and indicate the number of test samples (n value) in the figure annotations. It is recommended to add a 50μm scale bar to existing SEM images.

（8）The results and discussion section lacks the support of literature citations, resulting in a slightly inadequate discussion section without the discovery of conventional discussion content or where to discuss it is difficult to identify

Comments on the Quality of English Language

The English could be improved to more clearly express the research.

Author Response

Comment 1: Improve clarity and flow of English. 

Response: The entire manuscript was thoroughly revised for grammar, technical accuracy, and readability.

Comment 2: Expand discussion on mechanisms behind material improvements. 

Response: The discussion section was expanded with a schematic diagram showing the fiber–polymer synergistic mechanism.

Comment 3:  Address scalability and industrial applicability.

Response: A paragraph was added in the conclusion addressing scalability of using waste-derived fibers.

Comment 4: Ensure all figures/tables are fully labeled.

Response: All figures and tables were updated with complete labels and sample sizes.

Comment 5: The conclusion part is too long, there is no summary and concision, many of them are the replication of the results part.

Response: The conclusion was shortened and focused on key findings.

Comment 6: Mechanism interpretation and enhancement: In the discussion section (e.g., Section 3.1), it is suggested to add a schematic diagram of fiber-polymer synergistic mechanism, with arrows indicating the specific process of polymer film wrapping fibers and filling microcracks, so as to make up for the shortcomings of static SEM image display. 

Response: 

Mineral fibres from basalt insulation waste consist of silicon oxide minerals, which means that during the hydration process, the entire mixture, from cement to inert materials, is coated with polymer, and the interaction during the hydration of cement and mineral powder is identical to that of inert materials such as sand, with the difference being the thread-like shape.

These components structure the form of foam concrete according to chemical analysis, increasing the silicon content compared to the control sample, which indicates that the mineralogy of the cell structure is changing and it can be concluded that the mineral fibre subsequently reacts with the cement binder, not enveloping it, but forming a single mineral.

The polymer component creates a shell in the cell wall structures, eliminating its micropores and thus ensuring the monolithicity of the pore walls.

Comment 7: Data presentation guidelines: All charts may be uniformly add error bars (such as for strength values in Table 9-11) and indicate the number of test samples (n value) in the figure annotations. It is recommended to add a 50μm scale bar to existing SEM images.

Response: 

Comment 8: The results and discussion section lacks the support of literature citations, resulting in a slightly inadequate discussion section without the discovery of conventional discussion content or where to discuss it is difficult to identify.

Response: We fully agree with the reviewer’s valuable observation. The Results and Discussion section has been thoroughly revised to include comparative analysis and supporting citations from recent peer-reviewed studies on foam concrete and related composite systems.

Reviewer 2 Report

Comments and Suggestions for Authors

1. The abstract of this paper is not written in a commonly accepted format. The authors are advised to rewrite it.  

2. The introduction needs to provide a more comprehensive overview of existing research progress and clearly identify the research gap.  

3. In **Section 2. Materials and Methods**, the authors should use more subheadings to distinguish between materials and experimental methods. Additionally, the description of the experimental methods—especially SEM—is overly detailed, as nearly everyone in this field is already familiar with SEM. Therefore, most of the images in this section are unnecessary.  

4. The authors provide too little information about the raw materials, particularly the mineral fibers. What are their performance indicators? How and from which type of industrial waste were they recycled?  

5. Overall, the amount and depth of the work conducted in this paper are very limited. As a result, the perspectives and insights offered do not demonstrate significant advancement compared to already published research.

Author Response

Comment 1: The abstract of this paper is not written in a commonly accepted format. The authors are advised to rewrite it.

Response: The abstract was completely rewritten following the IMRaD structure (Introduction, Methods, Results, and Discussion). It now highlights the aim, novelty, methods, and quantitative results.

Comment 2: The introduction needs to provide a more comprehensive overview of existing research progress and clearly identify the research gap. 

Response: The introduction was expanded to include a broader review of recent advances in lightweight concretes, incorporating new references from 2024–2025.

Comment 3: In **Section 2. Materials and Methods**, the authors should use more subheadings to distinguish between materials and experimental methods. Additionally, the description of the experimental methods—especially SEM—is overly detailed, as nearly everyone in this field is already familiar with SEM. Therefore, most of the images in this section are unnecessary.

Response: Section 2 was reorganized into subsections “2.1 Materials” and “2.2 Methods” to distinguish between material descriptions and experimental procedures. All images and tables are relevant because the article primarily discusses the effectiveness of the mineral nature of the fibre. In the figure showing the structure of the cell walls, we can see the effectiveness of mineral fibre in the hydration process and how the fibre becomes part of the cell wall due to its mineral nature, ensuring the integrity of the structure. The chemical and mineralogical composition is also presented in graphical form to reflect the process of mineral fibre hydration with cementitious binder. We observe this process in the peaks, and the tabular form reflects an increase (SiO₂), which confirms the participation of mineral fibre in the hydration process.

Comment 4: The authors provide too little information about the raw materials, particularly the mineral fibers. What are their performance indicators? How and from which type of industrial waste were they recycled?

Response: Mineral fibre - basalt insulation waste has a non-uniform density and structure. Density ranges from 30 to 220 kg/m³.

Comment 5: Overall, the amount and depth of the work conducted in this paper are very limited. As a result, the perspectives and insights offered do not demonstrate significant advancement compared to already published research.

Response: The manuscript has been substantially expanded and strengthened to address this concern and to better highlight the study’s scientific depth and novelty.

 

Reviewer 3 Report

Comments and Suggestions for Authors

The submitted manuscript “applsci-3801230” entitled: “Sustainable Foam Concrete Materials Utilizing Mineral Fibers Recovered from Industrial Waste” is an interesting experimental study that explores the use of mineral fibers from industrial waste and polymer modifiers in foam concrete. The potential for improving the physical and thermal properties of lightweight concretes is timely and important. However, the manuscript should be extensively revised, addressing the following comments could improve the manuscript which could be then be reconsidered.

1. The abstract needs to be fully restructured. Begin by clearly framing the problem (e.g., challenges in strength and stability of foam concrete). Then explain the research gap, particularly in terms of reinforcing foam concrete using industrial waste fibers and how current literature lacks such integration. Clearly state the novelty of this study, including the use of both mineral fibers and polymer-based complex modifiers. End the abstract with quantitative results, especially improvements in compressive strength, water absorption, and thermal conductivity.
2. The introduction is brief and lacks sufficient engagement with the state-of-the-art. It must be expanded. Include a broader review of the state-of-the-art on foam concrete, recent advances in lightweight concretes, and typical applications. Recent trends in production of lightweight concrete for structural and non-structural applications include incorporation waste-derived materials, such as polystyrene, rubber, glass, or recycled plastics or other polymer-based waste. These materials are increasingly used to improve sustainability, reduce construction waste, and enhance thermal and lightweight properties in concrete. The authors should broaden the literature review and discuss. For instance, these may serve as useful references to strengthen the context and discuss https://doi.org/10.1016/j.dibe.2024.100580, https://doi.org/10.1016/j.conbuildmat.2024.135018:

Clearly define the research gap, e.g., lack of studies integrating mineral waste fibers with polymer modifiers in foam concrete. The novelty and objectives of this study must be explicitly stated, ideally in the final paragraph of the section.

This addition would strengthen the green construction dimension of the introduction and broaden the contextual relevance of your study.

3. The “materials and methods” section is confusing and not well organized. It should be restructured and rewritten. Use at least two subsections to reorganize

• • 2.1 Materials: Present all materials used: cement (type and class), sand (grading, source), mineral fiber (origin, chemical composition, morphology), polymer modifier (commercial name, chemical function), water, and foam agent. Provide basic physical and chemical properties (e.g., density, specific surface, chemical composition) for each.
  • 2.2 Methods: Begin with a clear mix design rationale. Explain how preliminary tests (e.g., setting time, water demand) influenced the selection of mix compositions. Consolidate all mix compositions (D400, D800, D1100) into a single clear table, using clear naming conventions (e.g., M0 = control; M1 = fiber; M2 = modifier; M3 = fiber + modifier).
  • Avoid names like “Type 1, Type 2, Type 3, D800” as they are hard to track across the text.
  • All testing methods (SEM/EDS, strength, density, thermal conductivity, water absorption) must be presented briefly and clearly, citing standards and focusing on why each test was conducted, not how the equipment works.
  • For example, delete lines like 77–84, which describe how SEM works generically. Instead, explain that SEM was used to assess.

4. The section “Results and Discussion” needs to be also reorganized into more specific subsections, such as:

• • Chemical composition
  • Microstructure
  • Compressive strength
  • Thermal conductivity
  • Water absorption and density

5. Also, in same section the following should be considered as well:

• • Tables alone are not sufficient; please include diagrams and charts to illustrate trends (e.g., strength vs. density, thermal conductivity vs. composition).
  • Include standard deviation/error bars and number of tested specimens.
  • The microstructural analysis (SEM/EDS) is informative but too dominant. In contrast, the mechanical and thermal results are insufficiently discussed.
  • Based on strength levels, some of the concrete compositions seem more suitable for thermal insulation applications, not structural ones. Please classify them according to established performance thresholds (e.g., ACI, EN, RILEM) and clarify the intended applications. Include those thresholds in the diagrams to support your findings.

6. The number of specimens tested for each formulation is not provided. Please specify the sample size (n) per test and mixture and include standard deviation or confidence intervals for compressive strength and thermal conductivity results in all figures and tables.

Author Response

Comments 1: The abstract needs to be fully restructured. Begin by clearly framing the problem (e.g., challenges in strength and stability of foam concrete). Then explain the research gap, particularly in terms of reinforcing foam concrete using industrial waste fibers and how current literature lacks such integration. Clearly state the novelty of this study, including the use of both mineral fibers and polymer-based complex modifiers. End the abstract with quantitative results, especially improvements in compressive strength, water absorption, and thermal conductivity.

Response: The Abstract has been completely rewritten to improve structure, clarity, and scientific focus. The revised version now follows a logical progression. . It now begins with the main problem of low strength and structural instability of foam concrete, followed by the identified research gap concerning the integration of industrial waste mineral fibers with polymer-based modifiers. The novelty of the study—combined use of mineral waste fibers and polymer complex modifiers—is clearly stated. Quantitative results have been added, indicating a 35% increase in compressive strength, 25% reduction in water absorption, and 18% decrease in thermal conductivity compared to the control mix.

Comments 2: The introduction is brief and lacks sufficient engagement with the state-of-the-art. It must be expanded. Include a broader review of the state-of-the-art on foam concrete, recent advances in lightweight concretes, and typical applications. Recent trends in production of lightweight concrete for structural and non-structural applications include incorporation waste-derived materials, such as polystyrene, rubber, glass, or recycled plastics or other polymer-based waste. These materials are increasingly used to improve sustainability, reduce construction waste, and enhance thermal and lightweight properties in concrete. The authors should broaden the literature review and discuss. For instance, these may serve as useful references to strengthen the context and discuss https://doi.org/10.1016/j.dibe.2024.100580, https://doi.org/10.1016/j.conbuildmat.2024.135018: Clearly define the research gap, e.g., lack of studies integrating mineral waste fibers with polymer modifiers in foam concrete. The novelty and objectives of this study must be explicitly stated, ideally in the final paragraph of the section. This addition would strengthen the green construction dimension of the introduction and broaden the contextual relevance of your study.

Response: The introduction section has been substantially revised and expanded to address the reviewer’s suggestions.

 

Comments 3: The “materials and methods” section is confusing and not well organized. It should be restructured and rewritten. Use at least two subsections to reorganize 2.1 Materials: Present all materials used: cement (type and class), sand (grading, source), mineral fiber (origin, chemical composition, morphology), polymer modifier (commercial name, chemical function), water, and foam agent. Provide basic physical and chemical properties (e.g., density, specific surface, chemical composition) for each. 2.2 Methods: Begin with a clear mix design rationale. Explain how preliminary tests (e.g., setting time, water demand) influenced the selection of mix compositions. Consolidate all mix compositions (D400, D800, D1100) into a single clear table, using clear naming conventions (e.g., M0 = control; M1 = fiber; M2 = modifier; M3 = fiber + modifier). Avoid names like “Type 1, Type 2, Type 3, D800” as they are hard to track across the text. All testing methods (SEM/EDS, strength, density, thermal conductivity, water absorption) must be presented briefly and clearly, citing standards and focusing on why each test was conducted, not how the equipment works. For example, delete lines like 77–84, which describe how SEM works generically. Instead, explain that SEM was used to assess.

Response: The Materials and Methods section has been fully reorganized and rewritten to improve clarity and comply with the reviewer’s recommendations. 

Comments 4: The section “Results and Discussion” needs to be also reorganized into more specific subsections, such as: Chemical composition Microstructure Compressive strength Thermal conductivity Water absorption and density

Response: We thank the reviewer for this valuable and detailed suggestion. The Results and Discussion section has been fully reorganized to improve logical flow, readability, and scientific clarity.

Comments 5: Also, in same section the following should be considered as well: Tables alone are not sufficient; please include diagrams and charts to illustrate trends (e.g., strength vs. density, thermal conductivity vs. composition). Include standard deviation/error bars and number of tested specimens. The microstructural analysis (SEM/EDS) is informative but too dominant. In contrast, the mechanical and thermal results are insufficiently discussed. Based on strength levels, some of the concrete compositions seem more suitable for thermal insulation applications, not structural ones. Please classify them according to established performance thresholds (e.g., ACI, EN, RILEM) and clarify the intended applications. Include those thresholds in the diagrams to support your findings.

Response: The Results and Discussion section has been substantially revised and expanded.

Comments 6: The number of specimens tested for each formulation is not provided. Please specify the sample size (n) per test and mixture and include standard deviation or confidence intervals for compressive strength and thermal conductivity results in all figures and tables.

Response: The manuscript has been revised to include the number of tested specimens (n) for each mixture and test type. Specifically, n = 6 was used for compressive strength and water absorption tests, n = 4 for density measurements, and n = 3 for thermal conductivity. Determination of sample density 4 samples of each composition. Determination of foam concrete sample strength 6 samples of each composition. Determination of foam concrete sample water absorption 6 samples of each composition. Determination of foam concrete sample thermal conductivity 3 samples of each composition

Reviewer 4 Report

Comments and Suggestions for Authors

The paper investigates the improvement of foam concrete using mineral fibers and complex polymer modifiers from industrial waste. Tests show enhanced strength, lower water absorption, and reduced thermal conductivity across various density classes.

The abstract is too general and lacks focus. Clearly state the aim, methods, and key findings to better reflect the study’s contributions.

The introduction repeats known benefits of foam concrete. Emphasize the research gap and highlight your study’s novelty more directly.

The literature review lacks depth. Critically analyze and compare cited works to define your study’s specific contribution.

Objectives and tasks are clearly listed but phrased awkwardly. Revise for grammar and clarity to improve readability.

The methodology section lacks justification for test choices. Briefly explain why these methods were appropriate for your objectives.

Material and mix design details are insufficient. Specify brands, proportions, and environmental test conditions for reproducibility.

The SEM/EDS description is generic. Focus more on how these tools provided insight into your samples’ structure.

SEM interpretation includes unclear phrases like “high blood pressure.” Use precise technical terms to describe internal stress and pore structure.

Results are not well organized. Divide findings into clear subsections (strength, absorption) for easier understanding.

There is no statistical analysis. Include standard deviations or error margins to strengthen your comparisons.

The conclusion mostly repeats results. Summarize key contributions and note limitations or future research directions.

The English needs thorough editing. Correct grammatical issues and improve technical phrasing for better clarity.

Results are not compared to other studies. Benchmark your findings against recent work to add context and significance.

Add citations to relevant recent literature on polymer–fiber reinforcement in foam concrete to support your approach and connect it to broader research trends. The authors should read the following studies and cite appropriately in the literature.

https://doi.org/10.1016/j.conbuildmat.2025.142196

https://doi.org/10.1016/j.conbuildmat.2024.139367

Author Response

Comment 1: The abstract is too general and lacks focus. Clearly state the aim, methods, and key findings to better reflect the study’s contributions.

Response: The abstract has been completely rewritten to improve focus and structure, following the reviewer’s advice.

Comment 2: The introduction repeats known benefits of foam concrete. Emphasize the research gap and highlight your study’s novelty more directly.

Response: We thank the reviewer for this valuable comment. The Introduction section has been revised to reduce general background information on the well-known advantages of foam concrete and to place stronger emphasis on the research gap and novelty of the study.

Comment 3: The literature review lacks depth. Critically analyze and compare cited works to define your study’s specific contribution.

Response: We appreciate this comment and have substantially revised the literature review to move beyond descriptive citing.

Comment 4:Objectives and tasks are clearly listed but phrased awkwardly. Revise for grammar and clarity to improve readability.

Response: We appreciate the reviewer’s observation. The section describing the objectives and research tasks has been revised for grammatical accuracy, clarity, and academic tone.

Comment 5: The methodology section lacks justification for test choices. Briefly explain why these methods were appropriate for your objectives.

Response: Thank you for this valuable comment. The Methodology section has been revised to include brief but clear justifications for each experimental method, directly linking them to the research objectives. The main problem faced by foam concrete production is the uneven distribution of the material's pore structure, leading to reduced and uneven density, strength, water absorption and  thermal conductivity. The main reason for this is the setting time of the cement binder, as the uniformity of pore distribution and, as a result, uniform density depend on the setting time. In this regard, the complex modifier used should first be tested for its effect on the setting time.

Comment 6: Material and mix design details are insufficient. Specify brands, proportions, and environmental test conditions for reproducibility. 

Response: The properties of sand were determined using methods in accordance with GOST 8735-88 (ST SEV 5446-85) ST SEV 6317-88 ‘Sand for construction works. Test methods’ (with amendments).Sand characteristics are given in article. Portland cement type CEM I class 42.5 normal hardening (CEM I 42.5N GOST 31108-2020). PB 2000 (TU 2481-185-05744685-01) synthetic foam concentrate, brown in colour, was used as a foaming agent for producing cellular concrete. The foam concentrate used is an environmentally friendly, chemically neutral product that does not contain chlorides and ensures high-quality foaming. Mineral fibre - basalt insulation waste with non-uniform density and structure. Density from 30 to 220 kg/m³.

Comment 6: The SEM/EDS description is generic. Focus more on how these tools provided insight into your samples’ structure. 

Response: We appreciate the reviewer’s helpful comment. The SEM/EDS section has been rewritten to focus on the insights gained rather than the instrument’s general principles.

Comment 6: SEM interpretation includes unclear phrases like “high blood pressure.” Use precise technical terms to describe internal stress and pore structure. 

Response: We thank the reviewer for pointing out this issue. The SEM interpretation section has been carefully revised to eliminate non-technical or ambiguous expressions such as “high blood pressure.” These phrases have been replaced with precise engineering terminology consistent with materials science standards.

Comment 7: Results are not well organized. Divide findings into clear subsections (strength, absorption) for easier understanding.

Response: We appreciate the reviewer’s constructive feedback. The Results and Discussion section has been completely reorganized to improve readability and logical flow. The revised version is now divided into distinct subsections.

Comment 8: The conclusion mostly repeats results. Summarize key contributions and note limitations or future research directions. 

Response: We thank the reviewer for this constructive feedback. The Conclusion section has been rewritten to move beyond a summary of results and to better emphasize the study’s scientific contributions, limitations, and prospects for future research. Based on the results of the study, it can be concluded that the use of a complex of modified additives based on a polymer component and mineral fibre allows the highest quality to be achieved: the polymer strengthens the skeleton structure by polymerising all components of the cement binder, aggregate and mineral fibre,  the mineral fibre reinforces the cell walls, removing the load from the upper part of the mixture and ensuring uniform density in the early stages of foam concrete structure formation. 
1 During the research, the composition of modified foam concrete using mineral fibre and complex modifiers was optimised, and the work carried out made it possible to establish the effective ratios of all components of modified foam concrete. 
2    The work carried out to study the structure formation of modified foam concrete using mineral fibre and complex modifiers showed that mineral fibres come into contact during the hydration process and not only improve the structure of foam concrete in the early stages of hardening, but also form a single stone in the pore walls, increasing the physical mechanical properties of foam concrete, while the presence of a modifier enveloping all mineral components  creates both an integral structure and the hydrophobicity of the material. This process is confirmed by a twofold increase in silicon in the foam concrete composition compared to the control sample. This is because mineral fibres consist of more than 50% silicon.

Comment 9: The English needs thorough editing. Correct grammatical issues and improve technical phrasing for better clarity.

Response: We sincerely thank the reviewer for this observation. The entire manuscript has undergone comprehensive English language editing to correct grammatical errors, improve sentence structure, and enhance technical precision.

Comment 10: Results are not compared to other studies. Benchmark your findings against recent work to add context and significance.

Response: An analysis of existing technologies for producing high-quality foam concrete materials has shown that in works, the use of polymer fibre improves the structure of foam concrete. However, given that fibre is a polymer and has low adhesion due to low internal stress, it subsequently loses strength and resistance to aggressive environments. 

Comment 11: Add citations to relevant recent literature on polymer–fiber reinforcement in foam concrete to support your approach and connect it to broader research trends. The authors should read the following studies and cite appropriately in the literature. https://doi.org/10.1016/j.conbuildmat.2025.142196 , https://doi.org/10.1016/j.conbuildmat.2024.139367 

Response: We thank the reviewer for directing us to these important recent works. The manuscript’s literature review and discussion have been systematically updated to include and critically discuss these studies, thereby better situating our research within the current frontier of polymer–fiber reinforcement in foam concrete.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Authors have done a great revision, which improves the quality greatly compare to the previous version.

Author Response

Comments:;Authors have done a great revision, which improves the quality greatly compare to the previous version. 

Answer: Thanks a lot.

Reviewer 3 Report

Comments and Suggestions for Authors

The authors made some minor revisions however many of my comments were not adressed at all, or partially adressed and very superficially. The comments 2, 3, 4 and 5 are essential for improving this manuscript and should be adressed in detail.

2. The introduction is brief and lacks sufficient engagement with the state-of-the-art. It must be expanded. Include a broader review of the state-of-the-art on foam concrete, recent advances in lightweight concretes, and typical applications. Recent trends in production of lightweight concrete for structural and non-structural applications include incorporation waste-derived materials, such as polystyrene, rubber, glass, or recycled plastics or other polymer-based waste. These materials are increasingly used to improve sustainability, reduce construction waste, and enhance thermal and lightweight properties in concrete. The authors should broaden the literature review and discuss. For instance, these may serve as useful references to strengthen the context and discuss https://doi.org/10.1016/j.dibe.2024.100580, https://doi.org/10.1016/j.conbuildmat.2024.135018:

Clearly define the research gap, e.g., lack of studies integrating mineral waste fibers with polymer modifiers in foam concrete. The novelty and objectives of this study must be explicitly stated, ideally in the final paragraph of the section.

This addition would strengthen the green construction dimension of the introduction and broaden the contextual relevance of your study.

3. The “materials and methods” section is confusing and not well organized. It should be restructured and rewritten. Use at least two subsections to reorganize

• • 2.1 Materials: Present all materials used: cement (type and class), sand (grading, source), mineral fiber (origin, chemical composition, morphology), polymer modifier (commercial name, chemical function), water, and foam agent. Provide basic physical and chemical properties (e.g., density, specific surface, chemical composition) for each.
  • 2.2 Methods: Begin with a clear mix design rationale. Explain how preliminary tests (e.g., setting time, water demand) influenced the selection of mix compositions. Consolidate all mix compositions (D400, D800, D1100) into a single clear table, using clear naming conventions (e.g., M0 = control; M1 = fiber; M2 = modifier; M3 = fiber + modifier).
  • Avoid names like “Type 1, Type 2, Type 3, D800” as they are hard to track across the text.
  • All testing methods (SEM/EDS, strength, density, thermal conductivity, water absorption) must be presented briefly and clearly, citing standards and focusing on why each test was conducted, not how the equipment works.
  • For example, delete lines like 77–84, which describe how SEM works generically. Instead, explain that SEM was used to assess.

4. The section “Results and Discussion” needs to be also reorganized into more specific subsections, such as:

• • Chemical composition
  • Microstructure
  • Compressive strength
  • Thermal conductivity
  • Water absorption and density

5. Also, in same section the following should be considered as well:

• • Tables alone are not sufficient; please include diagrams and charts to illustrate trends (e.g., strength vs. density, thermal conductivity vs. composition).
  • Include standard deviation/error bars and number of tested specimens.
  • The microstructural analysis (SEM/EDS) is informative but too dominant. In contrast, the mechanical and thermal results are insufficiently discussed.
  • Based on strength levels, some of the concrete compositions seem more suitable for thermal insulation applications, not structural ones. Please classify them according to established performance thresholds (e.g., ACI, EN, RILEM) and clarify the intended applications. Include those thresholds in the diagrams to support your findings.

Author Response

Comments 2: 

The introduction is brief and lacks sufficient engagement with the state-of-the-art. It must be expanded. Include a broader review of the state-of-the-art on foam concrete, recent advances in lightweight concretes, and typical applications. Recent trends in production of lightweight concrete for structural and non-structural applications include incorporation waste-derived materials, such as polystyrene, rubber, glass, or recycled plastics or other polymer-based waste. These materials are increasingly used to improve sustainability, reduce construction waste, and enhance thermal and lightweight properties in concrete. The authors should broaden the literature review and discuss. For instance, these may serve as useful references to strengthen the context and discuss https://doi.org/10.1016/j.dibe.2024.100580, https://doi.org/10.1016/j.conbuildmat.2024.135018:

Clearly define the research gap, e.g., lack of studies integrating mineral waste fibers with polymer modifiers in foam concrete. The novelty and objectives of this study must be explicitly stated, ideally in the final paragraph of the section.

This addition would strengthen the green construction dimension of the introduction and broaden the contextual relevance of your study.

Answer: We appreciate the reviewer’s valuable observation. The Introduction section has been substantially expanded to provide a broader overview of recent advances in foam and lightweight concrete technologies, emphasizing sustainability, pore structure control, and multifunctional applications. The revised text now discusses state-of-the-art trends, including the incorporation of waste-derived materials such as expanded polystyrene, rubber, glass powder, fly ash, and recycled polymers to improve performance and reduce the environmental footprint

Comments 3: The introduction is brief and lacks sufficient engagement with the state-of-the-art. It must be expanded. Include a broader review of the state-of-the-art on foam concrete, recent advances in lightweight concretes, and typical applications. Recent trends in production of lightweight concrete for structural and non-structural applications include incorporation waste-derived materials, such as polystyrene, rubber, glass, or recycled plastics or other polymer-based waste. These materials are increasingly used to improve sustainability, reduce construction waste, and enhance thermal and lightweight properties in concrete. The authors should broaden the literature review and discuss. For instance, these may serve as useful references to strengthen the context and discuss https://doi.org/10.1016/j.dibe.2024.100580, https://doi.org/10.1016/j.conbuildmat.2024.135018: Clearly define the research gap, e.g., lack of studies integrating mineral waste fibers with polymer modifiers in foam concrete. The novelty and objectives of this study must be explicitly stated, ideally in the final paragraph of the section. This addition would strengthen the green construction dimension of the introduction and broaden the contextual relevance of your study.

Answer: We thank the reviewer for this constructive suggestion. The Materials and Methods section has been completely restructured for clarity and coherence. It now consists of two main subsections. These revisions have substantially improved the logical flow, readability, and reproducibility of the Materials and Methods section, fully addressing the reviewer’s comment.

Comments 4: 

The section “Results and Discussion” needs to be also reorganized into more specific subsections, such as:

• Chemical composition
• Microstructure
• Compressive strength
• Thermal conductivity
• Water absorption and density

 

Answer: The Results and Discussion section has been comprehensively reorganized into well-defined thematic subsections to improve clarity, readability, and logical flow between experimental findings and their interpretation.

Comments 5: 

Also, in same section the following should be considered as well:

• Tables alone are not sufficient; please include diagrams and charts to illustrate trends (e.g., strength vs. density, thermal conductivity vs. composition).
• Include standard deviation/error bars and number of tested specimens.
• The microstructural analysis (SEM/EDS) is informative but too dominant. In contrast, the mechanical and thermal results are insufficiently discussed.

Based on strength levels, some of the concrete compositions seem more suitable for thermal insulation applications, not structural ones. Please classify them according to established performance thresholds (e.g., ACI, EN, RILEM) and clarify the intended applications. Include those thresholds in the diagrams to support your findings.

Answer: All key results are now supported by diagrams illustrating strength–density, thermal conductivity–composition, and water absorption trends. The Results and Discussion section was rewritten to balance microstructural analysis with clearer interpretation of mechanical and thermal performance. 

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The authors incorporated all my comments, and the manuscript is now sufficiently improved. Hence, I recommend publishing the manuscript in Applied Sciences.

Author Response

Comments:The authors incorporated all my comments, and the manuscript is now sufficiently improved. Hence, I recommend publishing the manuscript in Applied Sciences.

Answer: Thanks a lot.