Effect of Composite Fibers and Fly Ash on the Properties of Portland–Sulfoaluminate Composite Cement-Based Grouting Sealing Materials
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
It is an interesting topic and well written. Some suggestions:
For settling time in section 3.1, could you discuss with other studies?
In Figure 4 standard deviations were used, but in the text (line 215-220) you did not. Please add standard deviation in the text.
As shown in Figures, you did use you statistical analysis for some experiments, which statistical method did you use? please write it in Method section.
For section 3.3, you should improve discussion with other studies.
Author Response
It is an interesting topic and well written. Some suggestions:
1) For settling time in section 3.1, could you discuss with other studies?
Reply:
After careful consideration, in order to better demonstrate the experimental results, the author cited relevant literature to compare the experimental results.
2) In Figure 4 standard deviations were used, but in the text (line 215-220) you did not. Please add standard deviation in the text.
Reply:
Authors have optimized the expression of the corresponding text.
3) As shown in Figures, you did use you statistical analysis for some experiments, which statistical method did you use? please write it in Method section.
Reply:
A brief description of the statistical analysis methods used in this study has been added to the method overview section, as detailed in section 2.3.6
4) For section 3.3, you should improve discussion with other studies.
Reply:
Authors added new experimental data to enhance the scientific validity of the experiment in this section.
Reviewer 2 Report
Comments and Suggestions for AuthorsI find the manuscript well-written and interesting. Please, refer to the remarks presented below to increase the readability of the paper.
Line 20 and the whole manuscript - my suggestion is to replace the
term "blank sample" with "reference sample".
Line 23: replace "experimental group -9" with eg. "one of the
expermental groups". The potential reader is not familiar with the
denotations used in the manuscript when reading the abstract.
Line 25: format the keywords (lower/upper cases).
Line 40: move [8-10] before the period.
Line 125: replace "70mm*70mm*70mm" with "70mm x 70mm x 70mm".
Lines 149-150: Rephrase: "can penetrate the composition and
composition of materials for material analysis". The meaning is not
clear.
Line 161: correct - "Thermogravimetric analysis, also known as
thermogravimetric analysis".
Line 168: explain the abbreviation X-RD before its first use.
Figure 2 - please, change the colors to be more distinctive from each
other.
Figure 3 - please, remove the line in the graph. In my opinion, it has
no practical meaning in the interpretation of the results.
Line 233: move [46-48] before the period.
Figure 5 - please, change the colors to be more distinctive from each
other.
Line 292: refer to a specific figure.
Line 324: the expression "the strength is weak" should be replaced
with a more scientifically-sound one.
Line 342: use the upper case.
Reference no. 50 - correct the formatting.
I find the quality of English very good. Only a small number of issues reported.
Author Response
I find the manuscript well-written and interesting. Please, refer to the remarks presented below to increase the readability of the paper.
1) Line 20 and the whole manuscript - my suggestion is to replace the term "blank sample" with "reference sample".
Reply:
The description of the experimental group in the manuscript has been optimized and corrected
2) Line 23: replace "experimental group -9" with eg. "one of the expermental groups". The potential reader is not familiar with the denotations used in the manuscript when reading the abstract.
Reply:
Similarly, we have made corrections to the expression of experimental group labels in the manuscript
3) Line 25: format the keywords (lower/upper cases).
Reply:
We have proofread and corrected the capitalization of keywords
4) Line 40: move [8-10] before the period.
Reply:
We have revised the position of the references in the text.
5) Line 125: replace "70mm*70mm*70mm" with "70mm x 70mm x 70mm".
Reply:
We have replaced “70mm*70mm*70mm” with “70mm x 70mm x 70mm”.
6) Lines 149-150: Rephrase: "can penetrate the composition and composition of materials for material analysis". The meaning is not clear.
Reply:
The wording has been corrected, please refer to lines 204~205 for details.
7) Line 161: correct - "Thermogravimetric analysis, also known as thermogravimetric analysis".
Reply:
Authors have removed duplicate parts to make the sentence clearer.
8) Line 168: explain the abbreviation X-RD before its first use.
Reply:
The nouns in the manuscript have been appropriately defined.
9) Figure 2 - please, change the colors to be more distinctive from each other.
Reply:
Authors have optimized the color matching of Figure 2.
10) Figure 3 - please, remove the line in the graph. In my opinion, it has no practical meaning in the interpretation of the results.
Reply:
Authors have removed the lines in the image and optimized the overall image.
11) Line 233: move [46-48] before the period.
Reply:
We have revised the position of the references in the text.
12) Figure 5 - please, change the colors to be more distinctive from each other.
Reply:
Authors have optimized the overall image.
13) Line 292: refer to a specific figure.
Reply:
Authors cited research images and optimized the specific wording in the statement.
14) Line 324: the expression "the strength is weak" should be replaced with a more scientifically-sound one.
Reply:
After careful consideration, “the strength is weak” is replaced with “the strength is relatively poor”.
15) Line 342: use the upper case.
Reply:
Corresponding revisions have been made.
16) Reference no. 50 - correct the formatting.
Reply:
The references have been proofread and revised accordingly
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript "Effect of composite fibers and fly ash on the properties of Portland-sulfoaluminate composite cement based grouting sealing materials" contains many understatements and inaccuracies that require explanation.
General remarks
1. Authors should prefer to use the term "cement mortar" rather than "cement" in the case of hardened cement-water mixture with additives.
2. It should be explained how the values (Table 2) of compressive and flexural strength were tested. No determination of elastic modulus.
3. The authors should show in the manuscript the standard deviation (SD) and (COV) of the values presented in Table 2 and Table 3.
4. Please write how many samples were tested in total in the mentioned types of tests.
5. Please write in the manuscript what the dimensions of the samples were in the compressive strength test.
6. The designations WR1 – WR9 should be explained in the manuscript.
Specific remarks
7. 13 line: Explain the abbreviation PVAF, PPF. It should be in reverse order.
8. 55 line: You should write "... lower by 100-150℃ compared to OPC ...
9. 161 line: Please write what TG means and what DTG means.
10. 275 line, Fig.8: The designations "RP" and "OS" should be clarified.
11. 343 line: Should be "Conclusions".
The article may be published after thorough revision in the Coatings.
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
The manuscript "Effect of composite fibers and fly ash on the properties of Portland-sulfoaluminate composite cement based grouting sealing materials" contains many understatements and inaccuracies that require explanation.
General remarks
1) Authors should prefer to use the term "cement mortar" rather than "cement" in the case of hardened cement-water mixture with additives.
Reply:
After discussion, authors have made corrections to the corresponding statements in the manuscript.
2) It should be explained how the values (Table 2) of compressive and flexural strength were tested. No determination of elastic modulus.
Reply:
The parameters provided by the manufacturer did not include the elastic modulus, and this study did not involve the elastic modulus of the material, so this data was ignored; The testing process for strength values in Table 2 follows the same standard (GB/T50081-2019) as the compressive strength testing of materials in this study. The specific experimental process is as follows: In this study, a YAW-3000A1 pressure testing machine (maximum test force of 2000 KN) was used to test specimens of different age groups (1 day, 7 days, 14 days, 28 days) after curing. According to the relevant requirements of the "Standard for Testing Methods of Mechanical Properties of Concrete" (GB/T50081-2019), the pressure load loading speed was set to 0.5-0.8 MPa/s for testing. According to the experimental requirements, this study only focuses on the maximum failure stress during the loading process and does not discuss the stress curve or the failure mode of the specimen. Three samples were tested repeatedly for each group of experiments, and the arithmetic mean was taken as the test data value for the compressive strength of each group to reduce errors.
3) The authors should show in the manuscript the standard deviation (SD) and (COV) of the values presented in Table 2 and Table 3.
Reply:
The corresponding text has been optimized and appropriate expressions of error bars have been added.
4) Please write how many samples were tested in total in the mentioned types of tests.
Reply:
In the stages of setting time, fluidity, and mechanical testing, three sets of samples are set up for each experimental group, and the average value is taken after three tests as the final experimental result.
5) Please write in the manuscript what the dimensions of the samples were in the compressive strength test.
Reply:
Based on relevant testing standards and past research experience, a 70mm × 70mm × 70mm cube is used during the compression testing process.
6) The designations WR1 – WR9 should be explained in the manuscript.
Reply:
WR indicates that the experimental group has added a water reducing agent, and the description of WR in the study has been optimized accordingly.
Specific remarks
7) 13 line: Explain the abbreviation PVAF, PPF. It should be in reverse order.
Reply:
PVAF- Polyvinyl alcohol fiber; PPF- Polypropylene fiber.
8) 55 line: You should write "... lower by 100-150℃ compared to OPC …
Reply:
Authors have made corresponding modifications.
9) 161 line: Please write what TG means and what DTG means.
Reply:
TG- Thermogravimetric Analysis; DTG- Differential thermogravimetric Analysis. DTG performed differential processing based on TG analysis.
10) 275 line, Fig.8: The designations "RP" and "OS" should be clarified.
Reply:
In the original manuscript, RP represents the experimental group and OS represents the blank cement control group. After discussion, the author has made changes to the description of the experimental group in the manuscript.
11) 343 line: Should be "Conclusions".
Reply:
Authors have made corresponding changes.
The article may be published after thorough revision in the Coatings.
Reviewer 4 Report
Comments and Suggestions for AuthorsCoatings-3096459:
Follow my comments:
*Provide more detailed background on the current limitations of conventional cement materials in geotechnical engineering.
*Clearly state the main objectives of the study and the specific goals regarding the improvement of cement material properties.
*Include more detailed information about the sources and specific properties of the materials used, such as PVAF, PPF, and FA.
*Describe the experimental setup and procedures in more detail, including any specific equipment and conditions used during testing.
*Explain the hydration mechanism of the composite cement system, particularly how the addition of FA and fibers influences this process.
*Elaborate on the volcanic ash reaction mentioned and its impact on the production of hydration products and overall cement properties.
*Provide more details on how adding PPF-PVAF improves the strength performance of the cement system, including any relevant data or mechanisms.
*Clarify the impact of adding calcium hydroxide powder and FA on the fluidity of the cement system and its implications for practical applications.
*Discuss the long-term performance and durability of the modified cement materials, especially in real-world geotechnical applications.
*Provide more information on the environmental benefits of using SAC over conventional Portland cement, including specific data on CO2 emissions and energy consumption.
*Explain the challenges in controlling the setting time of SAC and how the proposed modifications address these issues.
*Offer more detailed results from the microstructure analysis, including specific findings from X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy.
*Include a comparative analysis between the modified cement system and traditional cement systems in terms of performance, cost, and environmental impact.
*Provide examples or case studies of how the modified cement materials have been or could be used in real-world geotechnical projects.
*Suggest directions for future research, particularly in areas where the current study has identified limitations or where further improvements could be made.
Comments on the Quality of English LanguageModerate editing of English language required.
Author Response
Follow my comments:
1) *Provide more detailed background on the current limitations of conventional cement materials in geotechnical engineering.
Reply:
The traditional cement materials currently used in geotechnical engineering projects mainly have the following problems:
- Traditional cement materials have low strength and cannot meet the increasing demand for high strength in practical engineering;
- Traditional cement materials have the disadvantage of setting time that is too long (for Portland cement) or too short (for sulfoaluminate cement), and need to be modified to control the setting time within a more favorable time period for grouting (120min~180min).
2) *Clearly state the main objectives of the study and the specific goals regarding the improvement of cement material properties.
Reply:
The main objective of this study is to combine OPC with SAC and add materials such as FA, PPF, and PVAF to the composite cement system to improve the compressive, flowable, and setting properties of cement materials. At the same time, micro testing and analysis methods are used to explore the reasons for the differences between the mixed cement system and ordinary cement.
The specific goals for improving the performance of cement materials are as follows: the setting time of the improved composite cement system can be controlled within 120min~280min; The compressive strength reaches over 10MPa after 7 days and over 25MPa after 28 days; At the same time as the compressive strength is increased, the flowability is not less than 120mm.
3) *Include more detailed information about the sources and specific properties of the materials used, such as PVAF, PPF, and FA.
Reply:
The experimental raw materials have been introduced in more detail in the manuscript, please refer to lines 122 to 131 for details.
4) *Describe the experimental setup and procedures in more detail, including any specific equipment and conditions used during testing.
Reply:
Experimental equipment, experimental conditions, and other experimental related descriptions have been added to the manuscript. Please refer to section 2 for details.
5) *Explain the hydration mechanism of the composite cement system, particularly how the addition of FA and fibers influences this process.
Reply:
After adding sulfoaluminate cement to ordinary Portland cement, the types of hydration products in the system did not change significantly. The hydration reaction is mainly divided into the following four stages: (1) pre induction period [1]: In this stage, the mineral phase in the cement system rapidly dissolves and produces ettringite, and compared to a single OPC system, this stage releases more heat and the rheological properties of the system deteriorate. The chemical reaction is shown in Equation 1; (2) Hydration induction period: During this stage, tricalcium silicate and gypsum components gradually dissolve, balancing the concentrations of calcium ions and sulfate ions in the system, and continuing to generate ettringite. The hardness and viscosity of the cement slurry begin to increase, and the chemical reaction is shown in equations 2 to 4; (3) Hydration acceleration period [2]: The rate of formation of tricalcium silicate increases, producing a large amount of hydrated calcium silicate and calcium hydroxide. Later, some of the generated calcium hydroxide reacts with the calcium sulfoaluminate component in the system to form ettringite. In this stage, a large amount of heat will be released, and the cement slurry will further harden. When the dosage of sulfoaluminate cement exceeds 20%~30%, the hardness of the cement slurry will begin to decrease, and the chemical reaction is shown in equations 5 and 6; (4) Hydration delay period: During this stage, the hydration reaction rate will gradually decrease, the types of hydration products will be basically fixed, the amount of substances will gradually accumulate, and the system strength will further increase.
（1）
（2）
（3）
（4）
（5）
（6）
Compared with the hydration reaction of a single cement system, the composite cement system releases more heat during the hydration process, and due to the presence of more sulfoaluminate, the amount of ettringite generated will be greater. However, when adding sulfoaluminate cement to Portland cement, the dosage of sulfoaluminate cement slurry needs to be considered to avoid performance degradation of the cement system due to excessive dosage.
References
[1] Zhang, J., Ye, C., Tan, H., & Liu, X. (2020). Potential application of Portland cement-sulfoaluminate cement system in precast concrete cured under ambient temperature. Construction and Building Materials, 251, 118869.
[2] Xu, L., Wu, K., Rößler, C., Wang, P., & Ludwig, H. M. (2017). Influence of curing temperatures on the hydration of calcium aluminate cement/Portland cement/calcium sulfate blends. Cement and Concrete Composites, 80, 298-306.
6) *Elaborate on the volcanic ash reaction mentioned and its impact on the production of hydration products and overall cement properties.
Reply:
Volcanic ash reaction refers to the reaction of volcanic ash materials such as fly ash, silica fume, and burnt gangue with lime at room temperature and in an environment containing water, to form a composite with hydraulic cementitious ability. Through volcanic ash reaction, the formation of hydration products such as hydrated calcium silicate, hydrated calcium aluminate, and hydrated calcium sulfoaluminate can be promoted [1-3]. The influence of volcanic ash reaction on cement hydration and overall performance of cement mainly includes the following points:
- Can promote cement hydration: The volcanic ash reaction is the reaction between the active components in the volcanic ash admixture and the calcium hydroxide released during the hydration process of cement clinker. This reaction process accelerates the hydration of cement, improves the hardening speed and strength development of cement-based materials.
- Enhance durability: Volcanic ash can react with minerals in cement to form new hydrates, which have good microstructural stability, thereby improving the durability of cement-based materials. In addition, volcanic ash can also reduce alkali aggregate reactions and oxidation reactions in cement-based materials, improving frost resistance and durability.
- Reduce heat release during cement hydration process: Volcanic ash reaction can reduce the heat release inside the cement system, thereby reducing the shrinkage and expansion of cement-based materials and reducing the risk of cracking and damage in the later stage of cement-based materials.
- Can enhance the adaptability of cement materials to the surrounding environment: Volcanic ash active materials can reduce the content of hydroxide ion carbonate in cement-based materials, reduce the degree and speed of corrosion of cement-based materials by the natural environment, and thus enhance the environmental adaptability of cement-based materials.
References
[1] Nie, S., Hu, S., Wang, F., Hu, C., Li, X., & Zhu, Y. (2017). Pozzolanic reaction of lightweight fine aggregate and its influence on the hydration of cement. Construction and Building Materials, 153, 165-173.
[2] Zheng, X., Liu, K., Gao, S., Wang, F., & Wu, Z. (2023). Effect of pozzolanic reaction of zeolite on its internal curing performance in cement-based materials. Journal of Building Engineering, 63, 105503.
[3] Kwon, Y. H., Kang, S. H., Hong, S. G., & Moon, J. (2017). Acceleration of intended pozzolanic reaction under initial thermal treatment for developing cementless fly ash based mortar. Materials, 10(3), 225.
7) *Provide more details on how adding PPF-PVAF improves the strength performance of the cement system, including any relevant data or mechanisms.
Reply:
According to relevant research, PVA fibers have excellent alkali resistance and good mechanical properties. At the same time, they are easily dispersed in water, have good affinity with cement, and high bonding strength. Currently, they have become one of the most widely used fibers in cement-based composite materials. PP fiber has the advantages of light weight and low cost, good chemical resistance, and can withstand most acid-base corrosion [1].
Many studies have shown that incorporating PVA fibers into cement-based composite materials can enhance the material's resistance to chloride ion penetration, and the addition of polyvinyl alcohol fibers can enhance the material's resistance to erosion and wear. In addition, studies have shown that although the addition of PVA fibers can reduce the fluidity of the slurry, the early strength performance of the cement system can be improved with the increase of fiber length [2-4]. After adding PP fibers into cement, the randomly distributed PP fibers can bridge cracks, control the development of cracks in cement under stress, enhance the overall compressive toughness, avoid brittle failure of the cement system, improve the failure mode of cement-based materials, and transform larger failures into multiple small cracks [5]. In summary, many existing studies have shown that PP fibers and PVA fibers have high crack resistance, corrosion resistance, and toughness, and are commonly used for modifying cement concrete materials. At the same time, they also have low carbon emission rates [6,7].
References
[1] Zhang, X., Du, M., Fang, H., Yao, X., Zhao, P., Du, X., ... & Shi, M. (2024). Development of a sprayable PVA-fiber-enhanced cement mortar with high acid-corrosion resistance for pipeline rehabilitate. Journal of Materials Research and Technology, 29, 4607-4621.
[2] Liang, L., Xu, Y., & Hu, S. (2022). Bending and crack evolution behaviors of cemented soil reinforced with surface modified PVA fiber. Materials, 15(14), 4799.
[3] Yao, X., Huang, G., Wang, M., & Dong, X. (2021). Mechanical properties and microstructure of PVA fiber reinforced cemented soil. KSCE Journal of Civil Engineering, 25, 482-491.
[4] Sikarskas, D., Antonovič, V., Malaiškienė, J., Boris, R., Stonys, R., & Šahmenko, G. (2021). Modification of the structure and properties of lightweight cement composite with PVA fibers. Materials, 14(20), 5983.
[5] Khan, S. Z., Rehman, Z. U., Khan, A. H., Qamar, S., & Haider, F. (2022). Effect of polypropylene fibers and cement on the strength improvement of subgrade lying on expansive soil. Iranian Journal of Science and Technology, Transactions of Civil Engineering, 46(1), 343-352.
[6] Abid, S. R., Shamkhi, M. S., Mahdi, N. S., & Daek, Y. H. (2018). Hydro-abrasive resistance of engineered cementitious composites with PP and PVA fibers. Construction and Building Materials, 187, 168-177.
[7] Lin, J. X., Song, Y., Xie, Z. H., Guo, Y. C., Yuan, B., Zeng, J. J., & Wei, X. (2020). Static and dynamic mechanical behavior of engineered cementitious composites with PP and PVA fibers. Journal of building engineering, 29, 101097.
8) *Clarify the impact of adding calcium hydroxide powder and FA on the fluidity of the cement system and its implications for practical applications.
Reply:
Generally speaking, when mineral admixtures such as silica fume, fly ash, or metakaolin are added to cement mortar, the calcium hydroxide produced by cement hydration can react with the silica in the mineral admixtures to produce volcanic ash products with bonding strength, which is beneficial for improving the mechanical properties and durability of the cement system [1,2].
Based on this, some researchers have added calcium hydroxide separately to the cement system to directly trigger the volcanic ash reaction, which occurs simultaneously with cement hydration and can further improve the mechanical properties and durability of the cement system [3-5].
With the improvement of mechanical and durability properties, the addition of calcium hydroxide can also reduce the rheological properties of cement systems. Therefore, in engineering practice, dispersants such as water reducers are usually added to modify cement materials to improve the flowability of the system.
References
[1] Neville, A. M. (1995). Properties of concrete (Vol. 4, p. 1995). London: Longman.
[2] Taylor, H. F. (1997). Cement chemistry (Vol. 2, p. 459). London: Thomas Telford.
[3] Shen, K., Qian, X., Hu, C., & Wang, F. (2023). Revisiting Ancient Roman Cement: The Environmental-Friendly Cementitious Material Using Calcium Hydroxide-Sodium Sulfate-Calcined Clay. ACS Sustainable Chemistry & Engineering, 11(13), 5164-5174.
[4] Weise, K., Ukrainczyk, N., Duncan, A., & Koenders, E. (2022). Enhanced Metakaolin Reactivity in Blended Cement with Additional Calcium Hydroxide. Materials, 15(1), 367.
[5] Shenbagam, V. K., & Chaunsali, P. (2022). Influence of calcium hydroxide and calcium sulfate on early-age properties of non-expansive calcium sulfoaluminate belite cement. Cement and Concrete Composites, 128, 104444.
9) Discuss the long-term performance and durability of the modified cement materials, especially in real-world geotechnical applications.
Reply:
The traditional cement materials currently used in geotechnical engineering projects mainly have the following problems:
- Traditional cement materials have low strength and cannot meet the increasing demand for high strength in practical engineering;
- Traditional cement materials have the disadvantage of setting time that is too long (for Portland cement) or too short (for sulfoaluminate cement), and need to be modified to control the setting time within a more favorable time period for grouting (120min~180min).
The composite cement-based materials obtained in this study have excellent mechanical properties, which can meet the high strength requirements of current geotechnical engineering. At the same time, due to the addition of PPF-PVAF composite fibers, the durability of cement materials has been further improved, which meets the needs of longer construction periods in practical engineering.
10) *Provide more information on the environmental benefits of using SAC over conventional Portland cement, including specific data on CO2 emissions and energy consumption.
Reply:
Compared with the ordinary Portland cement, sulfoaluminate cement has obvious advantages in energy savings and low-carbon emissions. The calcination temperature is low, and the carbon dioxide emission is significantly reduced in the production process. Due to technical limitations, no specific data related to it was found [1-3].
References
[1] Qinghuan Z., Transcending, leading and ambitious—review of the first international conference on sulphoaluminate cement materials science and engineering technology, China Concrete. (2013) 11, 55–58.
[2] Gao, Y., Li, Z., Zhang, J., Zhang, Q., & Wang, Y. (2020). Synergistic use of industrial solid wastes to prepare belite-rich sulphoaluminate cement and its feasibility use in repairing materials. Construction and Building Materials, 264, 120201.
[3] Wang, L., Ma, H., Li, Z., Ma, G., & Guan, J. (2021). Cementitious composites blending with high belite sulfoaluminate and medium-heat Portland cements for largescale 3D printing. Additive Manufacturing, 46, 102189.
11) *Explain the challenges in controlling the setting time of SAC and how the proposed modifications address these issues.
Reply:
SAC sets quickly, which may cause pipeline blockage during drilling and grouting. Therefore, in engineering, we usually add materials such as OPC, FA, and water reducing agents to delay the setting of SAC, so as to control the initial setting time of cement slurry between 100-160 minutes.
12) *Offer more detailed results from the microstructure analysis, including specific findings from X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy.
Reply:
We have conducted a more detailed analysis and research on the microstructure analysis section, and optimized the corresponding wording. See lines 428 to 522 for details.
13) *Include a comparative analysis between the modified cement system and traditional cement systems in terms of performance, cost, and environmental impact.
Reply:
In the experimental section, a comparative analysis of the performance, environment, and other aspects between the improved material of this study and traditional cement materials was added, and a summary was made in the conclusion section.
14) *Provide examples or case studies of how the modified cement materials have been or could be used in real-world geotechnical projects.
Reply:
The conclusion section has added a discussion on possible use cases in practical engineering, as detailed in lines 563 to 572.
15) *Suggest directions for future research, particularly in areas where the current study has identified limitations or where further improvements could be made.
Reply:
We have optimized the discussion of future research in the conclusion section, as detailed in lines 563 to 572.
Author Response File: 
Author Response.pdf
Reviewer 5 Report
Comments and Suggestions for AuthorsThe authors present a study on the influence of using polypropylene fibres (PVAF), polyvinyl alcohol fibres (PPF), and fly ash (FA) to modify Portland-sulfoaluminate composite cement to improve the workability of the cement-material system. For this purpose, the authors carried out tests on flowability, setting time and compressive strength on different mixes. In addition, the authors performed a limited microscopic analysis such as X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy on the composite cementitious system to characterise the hydration products, and explore the differences between the composite cementitious system and ordinary cement. Although the paper has a clear structure and some soundness, there are details that need to be improved to meet the minimum requirements of this journal.
Firstly, the authors should modify the abstract to include information on the microstructure analysis at some point. The authors include in this section some of the most relevant results of their research, such as strength values or differences in setting time, but do not provide any data extracted from the microstructural analysis. This might help to attract the reader's attention at some point. With this in mind, I would modify the keywords accordingly.
With regard to the introduction, the authors make a fairly extensive bibliographical review, referring to the different additions and fiber types included in the experimental plan. Personally, I think that the bibliography could be expanded by referring to more authors and works, and perhaps including more numerical data comparing the results of different studies. The aim of this is to give the reader a broader view of the research already carried out in these fields.
On the other hand, I would like to point out that the sentence between lines 40 and 43 should be referenced ("At present, SAC is gradually exposed to problems such as difficulty in controlling setting time and a decrease in the strength of cement in the middle and later stages, which limits its stability in engineering applications") as it is not part of the authors' own research.
With reference to the second section (experimental study), I would like to highlight some points that need to be modified, as they are difficult for a reader to understand right now. On the one hand, the mixtures (described in Table 4) should be referenced in the whole text in the same way, and I think it would be more convenient to use the reference indicated as "specimen code" (e.g. O-S-FA0.1, O-S-PVAF1.0, etc.). Using the code 1,2,3, 4...9 is very difficult as it forces the reader to constantly go back to table number four to find out which variant was being studied. The other codes make it easier to know whether it was FA or PPF or PVAF that was being used.
On the other hand, I would like to point out that in line 126-127, the authors should specify what the curing time was somehow, or at least clarify that they kept the curing chamber until the age of the trial, referenced later when describing the trials carried out.
The test methods are described in a very brief way, citing only the test standards. Perhaps more information should be included for each test. If necessary, the authors should include pictures of the tests if they consider it necessary. On the other hand, I would like the authors to answer some questions:
-why were 70x70x70 mm test specimens used? Alternatively, it would be possible to work with 40x40x160 mm specimens, which is a standard specimen. Are 70x70x70 specimens the specimens usually used in chinese codes?
-On the other hand, I would like to know how the authors carried out the grinding process for the extraction of samples used in microstructure tests such as the X-ray diffraction test. Were the samples also extracted from 70x70x70 mm specimens?
The answer to these questions should be included in the manuscript.
With respect to the presentation of the results, different aspects should be pointed out. On the one hand, the authors should use another code, such as O-S-FA0.1, O-S-PPF1.0, etc., instead of using numbers from 1 to 9 to refer to each mixture. This makes it very difficult to read. The graphs should be modified accordingly.
On the other hand, when compressive strength test is described, I do not understand why the authors only present results for 4 mixtures and not for the 9 analyzed in this study. The absence of these data makes it difficult to have an overall view of the work. For example, the statement that the authors include in lines 215-217 ("This may be due to the addition of fly ash in the experi-215 mental group delaying the hydration reaction of the cement system, resulting in a lack of 216 significant strength improvement in the early stage") could be justified if the data for the O-S-FA0.1 or O-S-FA0.2 mixtures were included.
During the description of the results, references such as "experimental group" should also be avoided in order to cite according to the code used throughout the text.
Section 3.3. is a previously undescribed section. During the experimental plan it is not specified that at some point in the study the possible influence of the addition of a polycarboxylate superplasticizer in the mixtures will also be analyzed. It is also not a study variable included in the abstract or in the objectives included at the end of the introduction section. Only in line 121 of the experimental plan was a sentence included indicating that water reducer was introduced into the mixer. Only here. The authors should include a more detailed description of this, so that the reader knows that at some point there are mixtures with water reducer and that they are studied.
On the other hand, when comparing mixtures with and without water reducer, the authors again limit the study to 4 mixtures and not all of them. I believe that a global view of the study should always be maintained. On the other hand, Figure 7 should be presented differently, as it is very difficult to read.
Finally, when microstructure analysis are described the authors limit it to two mixtures. If possible, one more should be included. However, I would like to emphasize that it is difficult to follow the description since abbreviations such as OS or RP are used referring to mixtures 1 and 9, or O-S-C and Mix-EXP. Each time they indicate one thing. This should be corrected.
In general, I think that in the results section the authors should include a much more detailed discussion, commenting on their results or perhaps comparing with work by other authors.
All in all, the authors should revise the conclusions.
Comments on the Quality of English LanguageMinor editing of English language required
Author Response
The authors present a study on the influence of using polypropylene fibres (PVAF), polyvinyl alcohol fibres (PPF), and fly ash (FA) to modify Portland-sulfoaluminate composite cement to improve the workability of the cement-material system. For this purpose, the authors carried out tests on flowability, setting time and compressive strength on different mixes. In addition, the authors performed a limited microscopic analysis such as X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy on the composite cementitious system to characterise the hydration products, and explore the differences between the composite cementitious system and ordinary cement. Although the paper has a clear structure and some soundness, there are details that need to be improved to meet the minimum requirements of this journal.
1) Firstly, the authors should modify the abstract to include information on the microstructure analysis at some point. The authors include in this section some of the most relevant results of their research, such as strength values or differences in setting time, but do not provide any data extracted from the microstructural analysis. This might help to attract the reader's attention at some point. With this in mind, I would modify the keywords accordingly.
Reply:
After discussion by authors, we have added relevant content on the micro analysis in the abstract section of this article.
2) With regard to the introduction, the authors make a fairly extensive bibliographical review, referring to the different additions and fiber types included in the experimental plan. Personally, I think that the bibliography could be expanded by referring to more authors and works, and perhaps including more numerical data comparing the results of different studies. The aim of this is to give the reader a broader view of the research already carried out in these fields.
Reply:
After authors’ discussion, appropriate references to existing research have been added to the manuscript.
3) On the other hand, I would like to point out that the sentence between lines 40 and 43 should be referenced ("At present, SAC is gradually exposed to problems such as difficulty in controlling setting time and a decrease in the strength of cement in the middle and later stages, which limits its stability in engineering applications") as it is not part of the authors' own research.
Reply:
We have screened relevant literature and cited them.
4) With reference to the second section (experimental study), I would like to highlight some points that need to be modified, as they are difficult for a reader to understand right now. On the one hand, the mixtures (described in Table 4) should be referenced in the whole text in the same way, and I think it would be more convenient to use the reference indicated as "specimen code" (e.g. O-S-FA0.1, O-S-PVAF1.0, etc.). Using the code 1,2,3, 4...9 is very difficult as it forces the reader to constantly go back to table number four to find out which variant was being studied. The other codes make it easier to know whether it was FA or PPF or PVAF that was being used.
Reply:
After discussion, the author has made changes to the description of the experimental group in the manuscript.
5) On the other hand, I would like to point out that in line 126-127, the authors should specify what the curing time was somehow, or at least clarify that they kept the curing chamber until the age of the trial, referenced later when describing the trials carried out.
Reply:
We have provided a more detailed description of the maintenance time during the experimental process.
6) The test methods are described in a very brief way, citing only the test standards. Perhaps more information should be included for each test. If necessary, the authors should include pictures of the tests if they consider it necessary. On the other hand, I would like the authors to answer some questions: -why were 70x70x70 mm test specimens used? Alternatively, it would be possible to work with 40x40x160 mm specimens, which is a standard specimen. Are 70x70x70 specimens the specimens usually used in chinese codes?
Reply:
Authors have extended and optimized the description of testing methods in the manuscript.
According to the relevant standard GB/T17671-2021 for strength testing of cement mortar, the 40x40x160mm test mold is one of the most common test mold sizes in mortar compression testing. It is usually used to measure the compressive strength of mortar. The trial mold of this size is suitable for mortar with particle size below 0.2mm, and it is required that the compactness of the trial mold must reach 100% after compaction. The 70 x 70 x 70mm test mold is also an important dimension in mortar compression testing. It is usually used for compressive testing of mortar with particle sizes ranging from 0.2mm to 4mm. Due to limited experimental equipment and conditions in this study, it cannot be guaranteed that the compactness of cement mortar samples will be maintained at 100%. Therefore, a 70 x 70 x 70mm cube test mold was selected for the production of test samples.
7) On the other hand, I would like to know how the authors carried out the grinding process for the extraction of samples used in microstructure tests such as the X-ray diffraction test. Were the samples also extracted from 70x70x70 mm specimens?
Reply:
The samples used in micro testing were extracted from the residual fragments of each sample after mechanical experiments.
The answer to these questions should be included in the manuscript.
8) With respect to the presentation of the results, different aspects should be pointed out. On the one hand, the authors should use another code, such as O-S-FA0.1, O-S-PPF1.0, etc., instead of using numbers from 1 to 9 to refer to each mixture. This makes it very difficult to read. The graphs should be modified accordingly.
Reply:
After discussion, the author has made changes to the description of the experimental group in the manuscript.
9) On the other hand, when compressive strength test is described, I do not understand why the authors only present results for 4 mixtures and not for the 9 analyzed in this study. The absence of these data makes it difficult to have an overall view of the work. For example, the statement that the authors include in lines 215-217 ("This may be due to the addition of fly ash in the experi-215 mental group delaying the hydration reaction of the cement system, resulting in a lack of 216 significant strength improvement in the early stage") could be justified if the data for the O-S-FA0.1 or O-S-FA0.2 mixtures were included.
Reply:
In order to increase the scientificity and reliability of the results, the author added experimental data in the study.
10) During the description of the results, references such as "experimental group" should also be avoided in order to cite according to the code used throughout the text.
Reply:
The numbering of each experimental group in the manuscript has been optimized.
11) Section 3.3. is a previously undescribed section. During the experimental plan it is not specified that at some point in the study the possible influence of the addition of a polycarboxylate superplasticizer in the mixtures will also be analyzed. It is also not a study variable included in the abstract or in the objectives included at the end of the introduction section. Only in line 121 of the experimental plan was a sentence included indicating that water reducer was introduced into the mixer. Only here. The authors should include a more detailed description of this, so that the reader knows that at some point there are mixtures with water reducer and that they are studied.
Reply:
The study on the impact of water reducing agents on various data of cement materials has been added in the post-processing section of the experiment. Please refer to section 3.3 for details.
12) On the other hand, when comparing mixtures with and without water reducer, the authors again limit the study to 4 mixtures and not all of them. I believe that a global view of the study should always be maintained. On the other hand, Figure 7 should be presented differently, as it is very difficult to read.
Reply:
The presentation of fig 7 has been optimized to make the data more intuitive.
13) Finally, when microstructure analysis are described the authors limit it to two mixtures. If possible, one more should be included. However, I would like to emphasize that it is difficult to follow the description since abbreviations such as OS or RP are used referring to mixtures 1 and 9, or O-S-C and Mix-EXP. Each time they indicate one thing. This should be corrected.
Reply:
The description of the experimental group in the manuscript has been uniformly optimized. Due to the author's experimental conditions and considerations for timeliness, the author will further optimize the experimental design of material microstructure analysis in future experiments.
14) In general, I think that in the results section the authors should include a much more detailed discussion, commenting on their results or perhaps comparing with work by other authors.
Reply:
Authors have elaborated on the discussion of the experimental results in the Results section of this study.
Round 2
Reviewer 3 Report
Comments and Suggestions for AuthorsIn the vast majority of cases, the authors took into account the comments regarding the manuscript. However, the following question should be answered:
The standard deviations (SD) of the tested samples have such large values. This automatically indicates a large dispersion of the results, which undermines the repeatability of the research results. This should be explained in the article. Once clarified, the article can be published.
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
Review#3 round2:
In the vast majority of cases, the authors took into account the comments regarding the manuscript. However, the following question should be answered:
The standard deviations (SD) of the tested samples have such large values. This automatically indicates a large dispersion of the results, which undermines the repeatability of the research results. This should be explained in the article. Once clarified, the article can be published.
Reply:
After the author's inspection, the data with excessive standard deviation in the manuscript was caused by an error in the data column used for plotting. It has been updated and reflected in the graph, as shown in line 295 to line 301.
Reviewer 4 Report
Comments and Suggestions for AuthorsCoatings-3096459R1:
Follow my comments:
The authors answered all questions and made desired changes to the text of the paper.
Comments on the Quality of English LanguageMinor editing of English language required.
Author Response
Reviewer#4 round2:
Coatings-3096459R1:
Follow my comments:
The authors answered all questions and made desired changes to the text of the paper.
Reply:
Thank you for the reviewer's recognition of this study. After further review by the author, the overall English writing has been optimized.
Reviewer 5 Report
Comments and Suggestions for AuthorsThe authors have carried out a thorough revision of the paper in line with the reviewers' comments. I believe that some details remain to be worked out in the final stage of publication of the paper:
-lines 24-25 (abstract), typing error, a full stop appears where it should be a comma.
-line 236, different typographies appear in the same text.
-I think that in the new figures (figures 8 or 9 for example) the font size should be modified so that the reader can identify each group without any inconvenience.
For the rest, I think everything is fine.
Author Response
Reviewer#5 round2:
The authors have carried out a thorough revision of the paper in line with the reviewers' comments. I believe that some details remain to be worked out in the final stage of publication of the paper:
-lines 24-25 (abstract), typing error, a full stop appears where it should be a comma.
-line 236, different typographies appear in the same text.
-I think that in the new figures (figures 8 or 9 for example) the font size should be modified so that the reader can identify each group without any inconvenience.
For the rest, I think everything is fine.
Reply:
After author proofreading, the spelling of symbols in lines 24-25 has been revised, and the overall format of the manuscript has been optimized accordingly.
After discussion by the author, the experimental group numbering text in the figure has been optimized to enhance readability, as shown in Figure 8 and Figure 9.
