Research Development and Key Issues of Pervious Concrete: A Review

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Reject

1. Significance of the research (review article) is missing in this manuscript.

2. There is no tables with interpretation of results are not found

3. Figure 1 and 2 taken from any other source or original research image?

4. Structure of the research are not properly organized

5. Practical implications of the real-world applications are not mentioned in the manuscript

6. There is no suggestions for improvement and future research directions are not found in the manuscript

7. If you are writing the review paper minimum 100 references (Recently published articles) need to refer.

Author Response

To peer reviewer:

Thank you very much for your enthusiastic suggestion. I have been busy revising the manuscript these days, and you have provided valuable feedback and suggestions. Making these modifications will take some time. Fortunately, I have completed the revision and submitted it to you today. Among them, the blue text represents your revision suggestions, the red text is explanatory prompts, and the orange text is supplementary and revised text. Thank you again for your guidance.

 

1. Significance of the research (review article) is missing in this manuscript.

According to the suggestion, the following supplementary materials have been added:

The research significance of this article mainly includes the following points: (1) By summarizing the mechanical properties and durability of current permeable concrete coarse aggregates, a coarse aggregate model with uneven surface appearance is proposed, providing theoretical and technical support for the study of improving the mechanical properties of PC. (2) Summarized important issues such as aggregate, particle size, water cement ratio, additives and admixtures, mix design, mixing and forming, and factors affecting porosity, providing a theoretical basis for the future design of permeable concrete preparation. (3) A new effective stress model for permeable concrete is proposed based on continuous porosity and effective stress of Taisha base, which can better fit the principle of effective stress. (4) By summarizing the research frontiers of permeable concrete, key issues that need to be addressed in current and future scientific research on permeable concrete are proposed.

 

 

2. There is no tables with interpretation of results are not found

According to the suggestion, the following supplementary materials have been added:

 

Table 1. Specification of natural coarse and recycled-concrete aggregates[19].

Specification	Dry-rodded unit weight,kg/m3		Relative density (specific gravity)	Absorption capacity	Size range
Natural coase aggregate(NCA)		1449	2.73	0.5%	0.3mm- 12.5mm
Recycled concrete aggregate(RCA)		1284	2.35	5.5%

 

Table 2. The processing process of recycled aggregates

Processing Processes	Pending Items	Equipment Used	Achieve the Goal
Crushing and Screening	Waste Concrete	Screening Equipment	Separate Aggregates
Removing Pollutants	Aggregate	Water Flotation Separators,Separators, and Magnets	Remove Impurities
Plastic Surgery Treatment	Recycled Aggregate	Mechanical Grinding Equipment	Improve Performance
Calcination and Grinding	Recycled Aggregate	Rotary Kiln	Remove Impurities
Final Program	The calcined aggregate can be further processed into the required particle size through grinding equipment.

 

Table 3 Strength characteristics of PC with cement as bonding material[56-63]

 

Factors                 Strength	water- cement ratio	porosity	Recycled aggregate particle size and grading	Replacement rate of recycled aggregate	Molding methods	Addition of fibers	Freeze-thaw cycle
Changes in compressive strength	↗↘	↘	↗↘	↘	↗	↗↘	↘
Changes in tensile strength	↗↘	↘	↗↘	↘	↗	↗↘	↘
Changes in flexural strength	↗↘	↘	↗↘	↘	↗	↗↘	↘

↗——Strength increase with Factors

↘——Strength decrease with Factors

↗↘——Strength increases first and then decreases with Factors

 

Table 4 Durability of PC with cement as bonding material[81-87]

 

Factors                 Durability	water- cement ratio	porosity	Recycled aggregate particle size	Replacement rate of recycled aggregate	Coefficient of thermal expansion of aggregate	Addition of rubber or fiber
Wear resistance changes	↗	↘	↗	↘	↗	↗
Changes in freeze-thaw damage	↘	↘	↗	↘	↗	↗
Resistance to sulfuric acid erosion changes				↘	↘

↗——Durability increase with Factors

↘——Durability decrease with Factors

↗↘——Durability increases first and then decreases with Factors

 

 

3.Figure 1 and 2 taken from any other source or original research image?

Figure 1 is a pre fabricated experiment taken in the laboratory of the School of Civil Engineering to produce permeable concrete manhole covers and vegetation permeable concrete components. The following two images are schematic diagrams drawn using 3D-MAX based on the text of permeable concrete. Figure 2 is a schematic diagram of the aggregate model, also drawn using 3D-MAX. The above are all original images.

4. Structure of the research are not properly organized

These days, I have reconsidered the research structure of the review article and made appropriate adjustments.

 

5. Practical implications of the real-world applications are not mentioned in the manuscript

This manuscript is a review article, not a research paper. If it is meaningful to the real world, it should enable readers to have an understanding of the current research and development status of permeable concrete, and to proceed with more in-depth research on this basis. And the significance of permeable concrete in the real world is explained in detail in the Introduction section.

 

6. There is no suggestions for improvement and future research directions are not found in the manuscript

In the Discussion section, we discussed improvement suggestions and future development directions in detail in four paragraphs.

 

 

7. If you are writing the review paper minimum 100 references (Recently published articles) need to refer.

According to the requirements, the references included in the manuscript are mostly excellent papers published in recent years, and more references have been consulted and included based on the opinions of the reviewers, allowing readers to have a more accurate understanding of the current development status and trends.

 

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

1. The manuscript introduces an effective stress model for pervious concrete based on continuous porosity and Terzaghi’s effective stress principle. However, the explanation of how the model aligns with the classic Terzaghi principle remains unclear. Could the authors provide more theoretical background and a detailed derivation to better justify this model?

2. The paper discusses the impact of aggregate size on both strength and permeability. However, it does not sufficiently explore the trade-off between these two critical properties. Could the authors add more discussion on how to optimize the balance between mechanical strength and permeability in pervious concrete? It could be strengthened by including more recent studies. (Specifically, https://doi.org/10.1016/j.cemconcomp.2024.105650) 

3. Figures 1 and 2, showing the ideal and actual models of PC, lack clarity. Can the authors improve the resolution of these figures and include additional annotations or explanations to make them easier to interpret?

4. In Sections 2.1 and 2.2, the treatment processes for recycled aggregates are not described in sufficient detail. Could the authors provide more specific information on how the aggregates were processed and any pre-treatment steps that were carried out?

5. The manuscript lacks detailed descriptions of the experimental procedures for measuring porosity and permeability. Could the authors provide more information on the specific testing procedures and apparatus used, similar to how UPV tests are described in other studies?

6. In Table 2, the differentiation between various concrete mix designs is unclear. Could the authors provide more detailed explanations of the differences between the variables, and clarify why certain parameters (e.g., cement content) differ for the control versus other mixtures?

7. The description of the influence of the “thickness of the slurry parcel layer” on mechanical performance in Section 3.1 is vague. Could the authors add more details about how this thickness was measured and what equipment was used to ensure accuracy?

8. The SEM images in Figures 3 have scales, but the scales are too small to be easily readable. Could the authors enlarge the scales and provide clearer indications of key features in these images?

 

Author Response

To peer reviewer:

Thank you very much for your enthusiastic suggestion. I have been busy revising the manuscript these days, and you have provided valuable feedback and suggestions. Making these modifications will take some time. Fortunately, I have completed the revision and submitted it to you today. Among them, the blue text represents your revision suggestions, the red text is explanatory prompts, and the orange text is supplementary and revised text. Thank you again for your guidance.

 

 

1. The manuscript introduces an effective stress model for pervious concrete based on continuous porosity and Terzaghi’s effective stress principle. However, the explanation of how the model aligns with the classic Terzaghi principle remains unclear. Could the authors provide more theoretical background and a detailed derivation to better justify this model?

I am a teacher who teaches soil mechanics. As shown in the following figure, the first figure is the calculation of effective stress for general saturated soil. Soil is a fragmented granular material, and the calculation reflects the magnitude of the contact force between particles; The second figure calculates the stress magnitude of the particles themselves, which is applicable to continuous porous media materials such as the continuous part of concrete skeleton. From these two figures, we can clearly see that the calculation section taken in the first figure is the contact point between soil particles, while in the second figure, we can see that the calculation section taken is the section passing through the solid. The research backgrounds corresponding to these two formulas are completely different. Many researchers tend to confuse these two formulas and overlook the reality that the theoretical backgrounds for their calculations are vastly different. Based on the theoretical frontiers related to concrete permeability in this manuscript, but I am not sure if it is appropriate to include a derivation process in the paper, so I did not rashly add a derivation comparing the properties of these two formulas.

 

 

2. The paper discusses the impact of aggregate size on both strength and permeability. However, it does not sufficiently explore the trade-off between these two critical properties. Could the authors add more discussion on how to optimize the balance between mechanical strength and permeability in pervious concrete? It could be strengthened by including more recent studies. (Specifically, https://doi.org/10.1016/j.cemconcomp.2024.105650)

 Guang-Zhu Zhang,Xiao-Yong Wang et al.[45]explored the impact of modified fibers on the self-healing performance and interfacial compatibility of microbial mortar and the experimental results confirm that the rough surface of the modified fibers facilitates the deposition of calcite produced by microbes and hydration products, promoting the early-stage healing rate.The strength of permeable concrete refers to its ability to withstand external forces without being damaged, mainly influenced by factors such as concrete mix strength, cement dosage, water cement ratio, and coarse aggregate dosage. The key to improving the strength of permeable concrete lies in optimizing these factors, such as determining appropriate cement dosage and water cement ratio. Using vibration molding, the strength increases first and then decreases. Table 3 summarizes the relationship between intensity and various factors.

 

Table 3 Strength characteristics of PC with cement as bonding material[56-63]

 

Factors                   Strength	water- cement ratio	porosity	Recycled aggregate particle size and grading	Replacement rate of recycled aggregate	Molding methods	Addition of fibers	Freeze-thaw cycle
Changes in compressive strength	↗↘	↘	↗↘	↘	↗	↗↘	↘
Changes in tensile strength	↗↘	↘	↗↘	↘	↗	↗↘	↘
Changes in flexural strength	↗↘	↘	↗↘	↘	↗	↗↘	↘

↗——Strength increase with Factors

↘——Strength decrease with Factors

↗↘——Strength increases first and then decreases with Factors

3.Figures 1 and 2, showing the ideal and actual models of PC, lack clarity. Can the authors improve the resolution of these figures and include additional annotations or explanations to make them easier to interpret?

 

The image is rendered using 3D-MAX and saved as a vector image. The clarity issue may be due to the three images being placed together, resulting in each image being smaller. I will provide a more detailed explanation of the images in the article.

 

 

 

 

 

 

 

3. In Sections 2.1 and 2.2, the treatment processes for recycled aggregates are not described in sufficient detail. Could the authors provide more specific information on how the aggregates were processed and any pre-treatment steps that were carried out?

 

Table 2 shows the processing process of recycled aggregates.

 

         Table 2. The processing process of recycled aggregates

Processing Processes	Pending Items	Equipment Used	Achieve the Goal
Crushing and Screening	Waste Concrete	Screening Equipment	Separate Aggregates
Removing Pollutants	Aggregate	Water Flotation Separators,Separators, and Magnets	Remove Impurities
Plastic Surgery Treatment	Recycled Aggregate	Mechanical Grinding Equipment	Improve Performance
Calcination and Grinding	Recycled Aggregate	Rotary Kiln	Remove Impurities
Final Program	The calcined aggregate can be further processed into the required particle size through grinding equipment.

 

5.The manuscript lacks detailed descriptions of the experimental procedures for measuring porosity and permeability. Could the authors provide more information on the specific testing procedures and apparatus used, similar to how UPV tests are described in other studies?

The experimental procedure for measuring porosity and permeability of permeable concrete mainly includes the following steps:

Porosity measurement:

Preparation of test specimens: Prepare permeable concrete test blocks with dimensions matching the measuring equipment container, and cure them in a standard curing room until the specified age.

Drying and cooling: Place the test piece in a drying machine at 105 ℃ until it reaches a constant weight, then take it out and cool it to room temperature in the dryer.

 

 

Fig Sample Dryer

Measurement and Calculation: Use volumetric or gravimetric methods to measure the porosity of the specimen. The volumetric method uses a vacuum densitometer, while the gravimetric method uses an electronic balance to calculate porosity by measuring the mass of the specimen in water.

Penetration measurement:

Measure the permeability of permeable concrete using the fixed head method or the falling head method. The fixed head method maintains a constant water pressure and calculates the permeability coefficient by measuring the amount of water that passes through the specimen over a certain period of time; The water head method uses a road permeability meter to calculate the permeability coefficient by measuring the change in water head over time. The laboratory often uses a concrete permeability coefficient tester to measure the permeability coefficient of processed samples. The concrete permeability coefficient measuring instrument mainly consists of a water storage cylinder, a sample connection seal, an overflow water tank, a measuring cylinder, etc. The detection accuracy is improved by circulating non aerated water. It has the advantages of simple structure, low price, easy operation, and low detection cost.

 

 

Fig  HC-APC Concrete Permeability Coefficient Tester‌

6. In Table 2, the differentiation between various concrete mix designs is unclear. Could the authors provide more detailed explanations of the differences between the variables, and clarify why certain parameters (e.g., cement content) differ for the control versus other mixtures?

According to the suggestion, the following content has been added：

At present, the influence of aggregate gradation, bone cement ratio, fly ash content, and reinforcement agent content on the compressive strength, splitting tensile strength, frost resistance, effective porosity, and permeability coefficient of permeable concrete is mostly studied through orthogonal experiments. By conducting experiments, the compressive strength, splitting tensile strength, frost resistance, effective porosity, and permeability coefficient of permeable concrete were obtained, as well as the optimal aggregate gradation, bone cement ratio, fly ash content, and reinforcing agent content data.

 

7. The description of the influence of the “thickness of the slurry parcel layer” on mechanical performance in Section 3.1 is vague. Could the authors add more details about how this thickness was measured and what equipment was used to ensure accuracy?

 

According to the suggestion, the following content has been added：

The thickness of the slurry increases with the increase of the water cement ratio, and the thickness of the slurry hanging on small-sized aggregates is higher than that on large-sized aggregates. The thickness of the slurry shows a trend of first increasing and then decreasing with the addition of fly ash. Due to the presence of a hardened layer of cement mortar on the surface of recycled aggregates, the bonding strength between recycled aggregates and new mortar decreases compared to natural aggregates. The increase in the replacement rate of recycled aggregates will significantly reduce the flexural strength of permeable concrete. The detection methods for the thickness of permeable concrete aggregate coating mainly include core drilling method and non-destructive method. The core drilling method is to directly measure the thickness of aggregate slurry by drilling core samples on permeable concrete structures. This method is intuitive and reliable, but it may cause certain damage to the concrete structure. The non-destructive testing method uses non-destructive testing techniques such as electromagnetic waves and ultrasonic waves to calculate the thickness of aggregate slurry by measuring the propagation speed of electromagnetic waves or ultrasonic waves in concrete. It has the advantages of easy operation and high efficiency, but the accuracy is relatively low. Optical microscope images can be used to analyze the thickness of the slurry coating layer on the surface of aggregate particles in permeable concrete.

 

8.Could the authors enlarge the scales and provide clearer indications of key features in these images?

Due to the fact that Figure 3 is quoted from a reference, our journal requires the consent of the other party, which may take a long time. Additionally, the impact of deletion is relatively small. Therefore, after communication with the editor, we plan to remove it from this manuscript.

 

‌‌‌

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors!

This article presents the research developments and key issues of pervious concrete. This review is of scientific and technical interest in the field of building materials. However, this work needs corrections. The manuscript may be published in this journal if the revised version fully takes into account possible comments:

1.     The introduction section lacks the purpose and objectives of the study.

2.     In paragraph 2.4. Cement admixtures and additives, there is no description and reference to Figure 3.

3.     In paragraph 4. Porosity, Permeability and Mechanical Characteristics, the mechanical characteristics are not studied: compressive strength, flexural strength and tensile strength, which are important for pervious concrete.

4.     Authors are advised to supplement the article with a comparison of the material under study with other analogs and also to highlight its positive properties.

5.     The list of references must be made in accordance with the rules of the Buildings journal.

 

Author Response

To peer reviewer:

Thank you very much for your enthusiastic suggestion. I have been busy revising the manuscript these days, and you have provided valuable feedback and suggestions. Making these modifications will take some time. Fortunately, I have completed the revision and submitted it to you today. Among them, the blue text represents your revision suggestions, the red text is explanatory prompts, and the orange text is supplementary and revised text. Thank you again for your guidance.

 

 

1. The introduction section lacks the purpose and objectives of the study.

According to the suggestion, the following content has been added：

The research objectives of this article mainly include the following points: (1) By summarizing the mechanical properties and durability of current permeable concrete coarse aggregates, a coarse aggregate model with uneven surface appearance is proposed, providing theoretical and technical support for improving the mechanical properties of PC. (2) Summarized important issues such as aggregate, particle size, water cement ratio, additives and admixtures, mix design, mixing and shaping, and factors affecting porosity, providing a theoretical basis for the design of future permeable concrete preparation. (3) A new effective stress model for permeable concrete is proposed based on the continuous porosity and effective stress of the Dasha base layer, which can better fit the principle of effective stress. (4) By summarizing the research frontiers of permeable concrete, key issues that need to be addressed in current and future scientific research on permeable concrete are proposed.

 

2. In paragraph 2.4. Cement admixtures and additives, there is no description and reference to Figure 3.

Due to the fact that Figure 3 is quoted from a reference, our journal requires the consent of the other party, which may take a long time. Additionally, the impact of deletion is relatively small. Therefore, after communication with the editor, we plan to remove it from this manuscript.

 

3. In paragraph 4. Porosity, Permeability and Mechanical Characteristics, the mechanical characteristics are not studied: compressive strength, flexural strength and tensile strength, which are important for pervious concrete.

According to the suggestion, the following content-----PART 4“Strength characteristics of PC

”has been added：

4. Strength characteristics of PC

Incorporating fibers into concrete can enhance the toughness and strength of microbial self-healing concrete. Additionally, research has shown that adding fibers can effectively control the development of cracks and promote the self-healing of larger microcracks[44]. Guang-Zhu Zhang,Xiao-Yong Wang et al.[45]explored the impact of modified fibers on the self-healing performance and interfacial compatibility of microbial mortar and the experimental results confirm that the rough surface of the modified fibers facilitates the deposition of calcite produced by microbes and hydration products, promoting the early-stage healing rate.The strength of permeable concrete refers to its ability to withstand external forces without being damaged, mainly influenced by factors such as concrete mix strength, cement dosage, water cement ratio, and coarse aggregate dosage. The key to improving the strength of permeable concrete lies in optimizing these factors, such as determining appropriate cement dosage and water cement ratio. Using vibration molding, the strength increases first and then decreases. Table 3 summarizes the relationship between intensity and various factors.

 

 

 

Table 3 Strength characteristics of PC with cement as bonding material[56-63]

Factors                     Strength	water- cement ratio	porosity	Recycled aggregate particle size and grading	Replacement rate of recycled aggregate	Molding methods	Addition of fibers	Freeze-thaw cycle
Changes in compressive strength	↗↘	↘	↗↘	↘	↗	↗↘	↘
Changes in tensile strength	↗↘	↘	↗↘	↘	↗	↗↘	↘
Changes in flexural strength	↗↘	↘	↗↘	↘	↗	↗↘	↘

↗——Strength increase with Factors

↘——Strength decrease with Factors

↗↘——Strength increases first and then decreases with Factors

It should be pointed out that using pressure molding and tamping molding, the strength increases both. The freeze-thaw degradation mainly comes from the deterioration of the interface between cement and aggregate, and can cause certain quality and strength losses. 

 

Table 4 Durability of PC with cement as bonding material[81-87]

Factors                   Durability	water- cement ratio	porosity	Recycled aggregate particle size	Replacement rate of recycled aggregate	Coefficient of thermal expansion of aggregate	Addition of rubber or fiber
Wear resistance changes	↗	↘	↗	↘	↗	↗
Changes in freeze-thaw damage	↘	↘	↗	↘	↗	↗
Resistance to sulfuric acid erosion changes				↘	↘

↗——Durability increase with Factors

↘——Durability decrease with Factors

↗↘——Durability increases first and then decreases with Factors

As the porosity increases, the ability to resist freeze-thaw damage decreases. Conversely, as the number of freeze-thaw cycles increases, the continuous porosity and permeability coefficient of recycled aggregate permeable concrete show an increasing trend. The two are mutually coupled and promote each other. For wear resistance, large particle size recycled coarse aggregate is significantly better than average recycled coarse aggregate or small particle size recycled coarse aggregate. Pre-treatment of recycled aggregates through physical or chemical methods significantly enhances durability. The addition of rubber and fiber significantly improves the freeze-thaw cycle resistance of concrete, improves internal fine cracks, reduces mass loss rate, and enhances

 

resistance to internal damage. Regarding the resistance to acid corrosion, the addition of rubber and fibers has a complex impact on the performance of concrete, and further research is needed to determine their specific role in acid resistance.

 

 

4.Authors are advised to supplement the article with a comparison of the material under study with other analogs and also to highlight its positive properties.

According to expert opinions, multiple parts of the article have been supplemented and improved.

 

5. The list of references must be made in accordance with the rules of the Buildings journal.

According to expert opinions, the arrangement of the article has been adjusted to meet the requirements of the journal

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

The article "Research Development and Key Issues of Pervious Concrete: A Review" presents a well-structured overview of current research on pervious concrete. It effectively discusses key aspects such as raw materials, porosity and permeability, mechanical properties, and durability of PC. Additionally, the authors propose new design methods and models, which enhance the article's relevance and utility for researchers and practitioners in the field of building materials. However, there are several areas that would benefit from further discussion and clarification:

 

 

1.      If possible, could you include essential graphical information from the cited articles, provided that copyright permissions can be obtained? Visual representations can significantly enhance the understanding of key features of the discussed materials.

2.      Would it be possible to provide some economic considerations regarding the application of pervious concrete, such as the cost per ton in comparison to analogous materials? What are the potential economic implications of implementing PC in mass construction?

3.      Given the absence of a unified standard for the preparation and testing of PC, what suggestions do you have regarding the establishment of preparation standards?

4.      Some sections, such as "Cement Admixtures and Additives," could benefit from summary tables that outline the additives used and their practical effects on the properties of PC. Additionally, could conclusions be drawn regarding which additives and modifiers are most effective in enhancing the properties of PC?

5.      The list of references would benefit from refinement to align with the journal's citation style.

Comments on the Quality of English Language

Minor editing of English language required.

Author Response

To peer reviewer:

Thank you very much for your enthusiastic suggestion. I have been busy revising the manuscript these days, and you have provided valuable feedback and suggestions. Making these modifications will take some time. Fortunately, I have completed the revision and submitted it to you today. Among them, the blue text represents your revision suggestions, the red text is explanatory prompts, and the orange text is supplementary and revised text. Thank you again for your guidance.

  

1. If possible, could you include essential graphical information from the cited articles, provided that copyright permissions can be obtained? Visual representations can significantly enhance the understanding of key features of the discussed materials.

 

 

 

 

 

2. Would it be possible to provide some economic considerations regarding the application of pervious concrete, such as the cost per ton in comparison to analogous materials? What are the potential economic implications of implementing PC in mass construction?

The economic benefits of PC are significant, mainly reflected in low maintenance costs, long service life, and significant savings in maintenance expenses.

Low maintenance cost: The unique material structure and construction technology of PC make its maintenance cost relatively low.

Long service life: PC pavement has good durability and a long service life, reducing the need for frequent pavement replacement.

Save maintenance costs: Due to low maintenance costs and long service life, PC can save a lot of maintenance costs for cities and has significant economic benefits.

In addition, PC can also bring environmental benefits, such as reducing rainwater runoff, increasing groundwater recharge, improving urban heat island effect, etc. These benefits indirectly promote the improvement of economic benefits. Therefore, the application of PC in urban road construction, landscaping and other fields has broad prospects.

 

3.Given the absence of a unified standard for the preparation and testing of PC, what suggestions do you have regarding the establishment of preparation standards?

 

The preparation standards for permeable concrete are strict, mainly including the following aspects:

Raw material selection: Choose ordinary Portland cement or slag Portland cement, with a grade not lower than 42.5; The particle size of coarse aggregate is generally 5-10 millimeters, and it is required that the particle size distribution be uniform; Less use of fine aggregate to increase porosity; Water must meet the standards for concrete mixing water; Regularly adding additives such as water reducing agents, air entraining agents, and reinforcing agents to improve performance.

Mix proportion design: Determine a reasonable water cement ratio (between 0.25-0.35), cement dosage (300-400 kilograms per cubic meter), coarse aggregate dosage (1300-1500 kilograms per cubic meter), and admixture dosage (generally accounting for 0.5% -2% of the weight of cement).

Mixing process: A forced mixer is used, with a mixing time of no less than 5 minutes, to ensure that the materials are thoroughly and evenly mixed.

Construction method: including template layout, concrete pouring, preliminary vibration, and surface leveling steps to ensure construction quality.

Maintenance measures: Wet curing should be carried out after construction to keep the surface moist for at least 7 days, prevent pore contamination, and ensure that the concrete strength and permeability meet the standards.

The performance requirements of permeable concrete mainly include the following aspects:

Permeable performance: The permeability rate is generally between 120-320 liters/㎡/min, with a maximum of over 700 liters/㎡/min. The gaps need to be regularly maintained to maintain permeability.

Freshly mixed performance: Low slump, usually between 20-50mm, not suitable for pumping; Rapid work-related losses require buffering; Strength is closely related to porosity.

Hardening performance: compressive strength between 3.5 and 28 MPa, flexural strength between 1 and 3.5 MPa; The apparent bulk density is between 1600-2000 kg/m3; Dry shrinkage is about half of that of ordinary concrete.

Durability: It has good frost resistance, and the overall frost resistance is ensured by rapid drainage.

Other performance: including high load-bearing capacity, good landscape effect, easy maintenance, frost resistance, durability, high heat dissipation, etc‌‌‌

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Accept the manuscript as it is

Reviewer 4 Report

Comments and Suggestions for Authors

Accept in present form