Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript titled “Synergistic microstructures, mechanical properties, and piezoresistive performance improvement of nanoengineered cementitious composites by CNT and GNP” presents an extensive experimental study on the influence of carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) on the performance of cement-based materials. The topic is of considerable interest in the field of smart construction materials and structural health monitoring. The paper is well organized and provides comprehensive experimental data, supported by microstructural and chemical characterization. However, the novelty of the study is not clearly highlighted, and the analysis remains largely descriptive. The writing quality and figure presentation require improvement for better readability. In general, the manuscript contributes useful findings to the understanding of nanocarbon synergy in cement composites, but it should be refined to meet the standards of clarity, rigor, and originality expected for publication.

Specific Comments
- The study makes a potentially positive contribution by investigating the synergistic effects of CNT and GNP on the mechanical and piezoresistive behavior of cement composites. The concept of combining one-dimensional and two-dimensional carbon nanomaterials is timely and valuable for enhancing multifunctional performance. Nevertheless, the paper does not sufficiently emphasize what is new compared with earlier studies. The authors repeatedly mention that research on GNP–CNT composites is “still in its infancy,” but they do not specify the exact gap in knowledge this work fills or how their approach improves upon previous methods. The discussion section summarizes results well but lacks a theoretical comparison with prior literature. Highlighting how the chosen ratios or findings extend existing understanding would strengthen the perceived contribution of the study.
- The experimental program is broad and includes various tests (mechanical, piezoresistive, microstructural, and chemical). However, certain elements reduce the perception of scientific rigour. The preparation and dispersion of nanomaterials are described only qualitatively without any quantifiable validation of dispersion uniformity. Statistical details such as standard deviations or confidence intervals are not reported for key data points, making it difficult to evaluate the repeatability and reliability of the results. Additionally, there is no discussion of experimental uncertainty or sensitivity analysis. While the testing methods themselves follow established standards, the lack of data variability metrics and dispersion quality assessment weakens the scientific robustness of the conclusions. Including quantitative analysis would make the findings more defensible.
- The manuscript is generally comprehensible, but the English language requires considerable editing. Several sentences are overly long, repetitive, or grammatically incorrect, which sometimes obscures the intended meaning. The flow between sections is occasionally abrupt, especially between the results and discussion. The terminology is not always consistent—for example, “flexural strength enhancement,” “bending strength,” and “toughness improvement” are used interchangeably. The frequent repetition of phrases such as “this observation indicates” or “it can be seen that” makes the text verbose. A more concise and precise writing style would improve readability. Proper sentence restructuring, consistent use of technical terms, and attention to verb tenses are strongly recommended.
- The introduction provides adequate background information on CNTs and GNPs, yet it fails to clearly identify the motivation and novelty of the present study. The authors mention limitations in individual GNP- or CNT-reinforced composites but do not explicitly articulate how their combined use in this work addresses those limitations differently from previous studies. The research objectives are embedded within the last paragraphs of the introduction, but they are not presented as clear hypotheses or research questions. The relevance of the findings to practical applications in smart concrete or real-world sensing systems could also be elaborated further. A more explicit statement of motivation, accompanied by a schematic summarizing the research concept and goals, would significantly enhance the clarity of purpose.
Recommendations for Improvement

• In Introduction Section, line 69–70: “When the GNP-reinforced cement-based composites under high stress, the interface gaps close completely, leading to a significant decrease in piezoresistive sensitivity.” is missing verb and grammatical error. Suggesting to change into: “When the GNP-reinforced cement-based composites are subjected to high stress, the interfacial gaps close completely, leading to a significant decrease in piezoresistive sensitivity.”
• In Table 5, write exact unit of Porosity is (%), remove the (nm)

• The caption for Figure 11 is incorrect. It is labeled "Results of FTIR"  but the figure clearly displays the pore percentage distribution from MIP analysis.

• The caption for Figure 12 appears to contain a typo. It lists "(k) and (l) 0.1% GNP+0.4% CNT", which seems to be a repetition of what is shown for panel (i). Please verify and correct the sample identification for these SEM images.

• In Section 2.2 (Sample preparation), it seem no verification of nanomaterial dispersion. You might need to add quantitative validation such as optical micrographs, sedimentation tests, or zeta potential data to demonstrate dispersion stability.

• In Section 3.1 (Mechanical properties), no standard deviations or statistical confidence reported. You should include error bars in Figures 3(a,b) and mention the number of replicates ( n = 2 or 3 ) also consider present data as “mean ± SD.”
• In Section 3.1 (Mechanical properties), the text refers to the results shown in "Fig.3". However, the corresponding bar charts are captioned as "Figure 2". The actual Figure 2 is the flowchart of the experimental methods. Please correct all figure numbers and their in-text citations throughout the manuscript.
• Suggestion for Figure 5: This figure, while comprehensive, is quite dense with 11 individual plots. For better readability and impact, I suggest reorganizing it. Consider creating a primary figure that directly compares the key samples: (a) Ref, (b) 0.5% GNP, (c) 0.5% CNT, and (d) the optimal 0.25% GNP + 0.25% CNT. This would effectively highlight the synergistic effect. The remaining plots could be moved to supplementary information.
• Proofreading: The manuscript is well-written, but a final proofread would be beneficial to catch minor grammatical errors. For example, on line 248, "This may due to..." should be "This may be due to..."

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

In this manuscript, GNP and CNT admixtures were added into cement-based materials to tune the mechanical strength, microstructures, and piezoresistive properties of the composite materials. The roles of GNP and CNT were investigated to address their synergistic mechanism under stress. In general, the work is well done, giving convincing evidences and discussion, leading to the conclusions. Before becoming fully acceptable, the manuscript is suggested to be revised according to the following comments:

1. Some English expression details should be checked, such as the sentence in Line 66, the sentence in Line 139, where “respectively” should be corrected as “separately”, and the sentence in Line 251, where “may be due to…” is correct; Some symbols should be used in correct way, such as that in Line 83, where an em dash rather than a hyphen should be used like “…under high stress—this helps…”, and that in Line 374, where an em dash is also needed like “..easily agglomerate—less CNT reduces…;
2. Scientific units should be expressed in correct way, such as those in Table 2, where multiple superscripts are not expressed correctly; Scientific symbols should be expressed in correct way, such as pH, which can not be written as PH;
3. In Figure 5, the stress vs time curves should be also given to facilitate understanding, as the resistance changes in fact with stress, not with time;
4. The TG tests are not professional and the results in Figure 8 are not adoptable. All samples should be well dried before TG tests, so as to provide an identical basis for comparison and for quantitative analysis; By the way, in this study, TG tests, and also FTIR measurements, are in fact not necessary;
5. When discussing Figure 10, the authors use the expressions “inferior pore size” and “optimizing function on pore size distribution”. Detailed statement should be given as to what is good, expected, or refined pore size.

Comments on the Quality of English Language

Some detailes should be paid attention to.

Author Response

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Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Your paper titled “Synergistic microstructures, mechanical properties, and piezoresistive performance improvement of nanoengineered cementitious composites by CNT and GNP” was read carefully and evaluated. According to my opinion, this paper is well organized and written. However, there are some issues that should be fixed at this stage. As an overall evaluation, a minor revision is required and you can find my comments / requirements below.

 

• Introduction lacks of literature surveys. This part should be enriched with more studies from the literture about this subject. It will be better for the readers to understand the position of this study in the literature.

 

• Grammatical errors in the manuscript (including errors in tables) should be fixed. For instance g/cm3.

 

• Obtained experimental mechanical results should be discussed and compared with literature studies. Hence, it is believed that importance of your findings can be understood better. In addition, the influence of percentage of the additives should be discussed more.

 

• Determination of the size of the pores should be explained with details in material and method section.

 

• Scale bars should be added into the SEM images.

 

• Future work possibilites should be added into the conclusion part.

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

Manuscript ID: buildings-3932493

Title: Synergistic microstructures, mechanical properties, and piezo-resistive performance improvement of nanoengineered cementitious composites by CNT and GNP

The manuscript presents a well-structured and systematic study on the synergistic effect of the combined addition of Graphene Nanoplatelets (GNP) and Carbon Nanotubes (CNT) on cementitious composites. Unfortunately the paper misses some parts and without a complete check by the authors of the paper structure, a complete review is not possible. 

 

COMMENT 1:

At page 8, the figure “Flowchart of sample preparation and test methods….” is wrongly labeled as Figure 2, that instead is used at page 5. The authors have to carefully check the whole paper in order to identify and correct all the typos.

COMMENT 2:

At line 192, the text refers to Fig.2d but no letter d is present in the Figure. Please check these typos in order to make the paper clearer.

COMMENT 3:

There is an important typo that cannot consent an evaluation of the paper. In section 3.2, at line 325 the authors say “…which will be explained in section 3.6” but not section 3.6 is present in the text. Thus, the sentence “In contrast, when the GNP content is relatively high, the changes in electrical resistivity degrade rapidly under low stress conditions, whereas they remain nearly unchanged under high stress” that represents a very important statement for the paper is merely stated. Without a complete check by of the authors of the whole structure of the paper, a complete review is not possible. Moreover, the most important part of the article, which is the discussion, is limited to only a few lines, turning the preceding findings into a statement. In-deep explanation must be provided. 

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors have thoroughly addressed all the points raised in the previous round of review. They have provided clarifications, incorporated additional experimental data, and revised the manuscript accordingly. All my concerns have been satisfactorily resolved. The manuscript is now significantly improved and is suitable for publication.

Author Response

Once again, thank you very much for your comments and suggestions.

Reviewer 4 Report

Comments and Suggestions for Authors

COMMENT 1:

The discussion of the obtained results should be clearer, in order to justify the overall multifunctional behavior of the sample. What is the mixture that guarantees the best balance between mechanical and sensing performance? Is it 0.25%/0.25%? Please provide more details.

COMMENT 2:

As deducible from the work, the paper highlights that GNP dominates performance at low stress, while CNT dominates performance at high stress due to unclosed tiny interfacial gaps. This could be a good point, please provide in-depth discussion.

Author Response

Please find the response in the attachment.

Author Response File: Author Response.docx