Influence of the Nature of Cement on the Physical and Mechanical Properties of Soil Concretes from Sandy Clay and Laterite

Response to Reviewer 1 Comments

1. Summary

Thank you for taking the time to review this manuscript. Please find the detailed answers below and corrections in the resubmitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Yes

Are all the cited references relevant to the research?

Yes

Is the research design appropriate?

Yes

Are the methods adequately described?

Yes

Are the results clearly presented?

Yes

Are the conclusions supported by the results?

Yes

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: Abstract: the abstract need to be summarised the main points and avoid the unnecessary parts to better understanding and readability. -Please underscore the scientific value added in the abstract. Add some of the most critical quantitative results to the Abstract.

Response 1: Thank you for pointing this out. We have incorporated all the comments made in the abstract section of this article.

Comments 2: The citation should be revised. Refer to the most recent and relevant references.

Response 2: Thank you for pointing this out. We agree with this comment. Therefore, we have revised and standardised all the quotations in the article. We also relied on recent and relevant references on the subject. For example, those of (Hessouh et al., 2023), (33. X. Guo et al., 2022) and (Helson et al., 2018) which are referenced 21, 33 and 30.

Comments 3: Avoid unnecessary and repeated sentences. 

Response 3: Thank you for pointing this out. The comment has been considered by eliminating unnecessary and repeated sentences.

Comments 4: Before using any abbreviation, the full term must be explained in the text.

Response 4: Thank you for pointing this out. The comment was considered by first explaining the abbreviation before using it in the article.

Comments 5:  Did the authors measured the second C- S- H gels additional?? As we know any Pozzolan material they reacts with Ca(OH)2 Produced second C- S- H gels…Please explain widely?  Also very important to know time of curing after 90 days or more?? The reactions happening on long terms? Please explain widely?

Response 5: Thank you for pointing this out.

-        The second additional C-S-H gels were not measured, as this article did not dwell on the chemical aspects (XRD, EDX) of the material. We focused much more on the physical and mechanical aspects.

-        The reaction between Portlandite produced by cement hydration and the Si and Al in the soil is known as the pozzolanic reaction (Porbaha et al. 2000). The hydrated calcium silicates (CSH) formed from kaolinite are mono- and dicalcium hydrates (Khay, 2012) which structurally correspond to an imperfect form of tobermorite and jennite (Taylor, 1997). These CSH have a reticular structure (Locat et al. 1990). In kaolinite, the calcium aluminate formed is tricalcium, and a second gel is also formed, C-S-A-H, which has a lamellar structure (Locat et al. 1990).

-        Yes, it is important to know the curing time after 90 days and more. Especially for formulations with CEM III 32.5, which is a slag cement.  With this type of cement, we generally observe the development of long-term compressive strength, which is the result of chemical reactions that take place during this period.

-        On contact with water, an amorphous aluminate-rich gel and ettringite nuclei are formed in the short term (Taylor, 1997). Then, the calcium in solution gradually increases and the C3S react with the water to form an 'impermeable' layer of calcium silicates (CSH) on the surface of the grains. The quantity of CSH formed is preponderant, that of ettringite low, and all the Portlandite is consumed by the formation of CSH (Lothenbach et al. 2011). However, the hydrate layer around the anhydrous cement grains thickens more slowly and illustrates the difference in attack processes between slag and clinker, which is responsible for the initially slower development of mechanical strength (Van Rompaey, 2006).

Response to Reviewer 2 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Must be improved

Are all the cited references relevant to the research?

Must be improved

Is the research design appropriate?

Must be improved

Are the methods adequately described?

Can be improved

Are the results clearly presented?

Can be improved

Are the conclusions supported by the results?

Can be improved

3. Point-by-point response to Comments and Suggestions for Authors

MAJOR CONCERNS

Comments 1:  Extensive research has been performed on the topic. The authors do not add to the knowledge gap. Numerous papers on the topic can be found when one searches Google Scholar. The authors have not provided any discussion of the novelty of their research. The only sentence given by the authors is line 81 in the manuscript ("In the past, studies on soil concretes were much more limited to artificial soils but 81 also to underground structures"). This statement is incorrect and it does not serve as a novelty justification

Response 1: Thank you for pointing this out. This article deals with soil concrete and not soil-cement. The first work on this material was carried out in the IFSTAR laboratory, using a geotechnical approach on artificial soils (kaolinite, Fontainebleau sand, Triel sand, Fréjus sand, Archères sand). The binder used here was CEM III 32.5 C. The scientific work that followed was the theses of (Szymkiewicz, 2011) and (Guidmond-barrett, 2013) with several articles. Further work was carried out in the L2MGC laboratory following a concrete approach with the work of (Helson, 2017) who always worked on artificial soils (kaolinite, Fontainebleau sand) with CEM III 32.5 C cement as the binder and whose objective was to evaluate the influence of the clay content on the properties of the soil concrete. This was followed by the work of (Jacques Hessouh, 2021), who began working on reworked natural soils with CEM III 32.5 C as the binder, and whose objective was to compare the properties of soil concrete produced on site with that produced in the laboratory. The work in this article is carried out in the L2MGC laboratory and is a continuation of the work carried out by (Helson, 2017) and (Hessouh, 2021) on reworked natural soils (clayey sand and laterite) with CEM I 52.5 N, CEM II 42.5 R and CEM III 32.5 as binders. The aim of this study is to investigate the influence of the nature of the binder on the properties of the material.

Comments 2: The soils used in the research are exclusively located in Cameroon. How are these soils compared to other locations in the world? Are the results of this research of interest anywhere other than Cameroon? The results may only be of interest locally (Cameroon). Will this manuscript read by the general researcher in the world especially there are numerous articles published in this topic?

Response 2: Thank you for pointing this out.

-        The soils used in this work were subjected to a GTR classification, which is an internationally recognised soil classification. According to the classification, clayey sand and laterite are classified as A3, i.e. very plastic silty soils.

-        We encounter very plastic silty soils in France and just about everywhere else in the world, so yes, all the results of this research are of interest elsewhere than in Cameroon.

-        The results are not just of local interest (Cameroon).  All the soils and cements used were characterised and referenced against standards. This means that any soil in the world with the same classification can be used as a basis for the results.

-        This manuscript deals with the influence of the nature of the soil on the physical and mechanical properties of soil concretes. The concept of soil concrete, which is a material produced in-situ that consists of mixing the soil in place with a hydraulic binder and water, and whose applications are the improvement of soils for pavements and the construction of dykes. It is different from soil-cement, which has much more building applications.

Comments 3: How does the cement used compare with other cement produced in the world?

Response 3: Thank you for pointing this out. Standard NF EN 197-1 classifies cements into five types according to composition. In our study, we worked with three types of cement with the following characteristics:

-          CEM I 52.5 N consists of clinker with a content of between 95 - 100 % and secondary constituents of between 0 - 5 %. The chemical properties are given in table 3 (line 137).

-          CEM II 42.5 R consists of clinker with a content of between 65 - 94 % and other main constituents of between 6 - 35 %. The chemical properties are given in Table 3 (line 137).

-           CEM III 32.5 C consists of clinker with a content of between 5 - 64 % and other main elements of between 36 - 95 %. The chemical properties are given in Table 3 (line 137).

SPECIFIC COMMENTS

Comments 1: Soil Concrete is the terminology used in the manuscript. The traditional terminology is Soil Cement.

Response 1: Thank you for pointing this out. The terminology used in this article is "Soil concrete", which refers to in-situ concrete made from a mixture of soil, cement, and water. As a result, there is no excavation of aggregates (soil) and the soil in place is used to build the structures. There are two main methods: Soil Mixing, which is used for soil improvement, waterproofing and retaining walls, and Jet Grouting, where the fluid is injected under pressure, for example to build dykes. This is different from the term "Soil cement", which refers to earth concrete, which is used much more in buildings.

Comments 2: Why three different cements are used. Are they specified for different conditions?  Are there a differences between these three? If yes, what are they?

Response 2: Thank you for pointing this out.

-          Three cements are used because the aim of this article is to study the influence of the nature of the cement on the physical and mechanical properties of soil concretes based on sandy clay and laterite. We worked with three types of cement: CEM I 52.5, CEM II 42.5 and CEM III 32.5.

-          Yes, we have CEM III 32.5 C and CEM I 52.5 N produced in France by Calcia and Eqiom respectively. CEM II 42.5 R is produced in Cameroon by Cimencam, a subsidiary of the Lafarge group.

-          Yes, there is a difference between these three cements. They are specified in Table 3 (line 137) of the article.

-           

Comments 3: Lines 35 - 37. The authors state "On the one hand, it limits the destruction of the marine ecosystems from which the sediments used in concrete are extracted, reducing the multiplication of aggregate quarries and their abusive exploitation. On the other hand, it reduces the considerable carbon footprint of the transport of aggregates to the construction sites." The authors do not provide any data  to support the claims in these sentences. Additionally, these sentence argue against the use of cement. However, the researchers used cement. The reader will be confused with this contradiction. Additionally mentioning phrases like "abusive exploitation" is a highly politically charged phrase to which other people may disagree with. Such phrases do not belong in a technical paper.

Response 3: Thank you for pointing this out. We agree with this comment. Therefore, we have removed.

Comments 4: entence starting line 37. This statement is not true. Generally, we can confidently determine the strength of materials except for geomaterials.

Response 4: Thank you for pointing this out. The material studied here is soil concrete, which is a material produced in-situ from a mixture of soil, cement, and water. There is no excavation of the soil, and the binder and water are mixed or injected using equipment on the surface or at depth (Soil-mixing and Jet grouting). Depending on the depth or a linear surface, the variability of the layers and the heterogeneity of the soil mean that it is not always easy to predict the compressive strength of the material. This has been demonstrated by studies (Jacques Hessouh, 2021) which compared the mechanical properties (compressive strength) of a soil concrete made in the laboratory with one made on site.

Comments 5: Sentence starting line 39. It is not clear how many factors the authors are listing, 3, 4 or 5

Response 5: Thank you for pointing this out. there are 04 factors (well-founded comment). This has been corrected (line 37).

Comments 6: The two sentences starting line 41. These sentences appear very abruptly without any connection to the previous sentence. The second sentence provides the results of the study: "The results showed an increase compressive strength as a function of the cement content". This is very well known fact. It is nothing new.

Response 6: Thank you for pointing this out.

-          This has been corrected in the article (line 36 – 38).

-          We have removed the remark about the increase in compressive strength as a function of cement content.

-           

Comments 7: Line 51. What material is "this material"?

Response 7: Thank you for pointing this out. Soil concrete is the material. This has been corrected in the article (line 48).

Comments 8: Line 162. "...the 161 W/C ratio is chosen intuitively... ".  What is meant by intuitively? The W/C ration is a very important parameter in developing the strength of the soil cement. Arbitrary use of the W/C value can be very misleading.

Response 8: Thank you for pointing this out. The W/C ratio is chosen for values that allow a self-placing floor concrete to be achieved, i.e. a spread of between 32 and 33 cm. This has been corrected in the article (line 158 – 159)

Comments 9: Line 171. "After several spreading tests, the water content of the mixture is determined in accordance with the workability assumption". What is this assumption? What standard is used for this assumption?

Response 9: Thank you for pointing this out. The workability assumption is to obtain a self-placing floor concrete, i.e. a spread of between 32 and 33 cm. This is a recommendation, as there is as yet no standard on this subject for soil concretes.

Comments 10: Tables 5, 6 and 7. What is the moisture content of the soils used? The total moisture in the mixture is the total of the moisture present in the soil and the additional water added to the mix. Without knowing the moisture content of the soil, the W/C ratios cannot be accurately determined.

Response 10: Thank you for pointing this out. In our study, we pre-dry our soil samples for 24 hours in an oven at a temperature of 60°C until a constant mass is obtained.

Response to Reviewer 3 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Can be improved

Are all the cited references relevant to the research?

Can be improved

Is the research design appropriate?

Can be improved

Are the methods adequately described?

Can be improved

Are the results clearly presented?

Can be improved

Are the conclusions supported by the results?

Can be improved

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: For cement, the content of mineral components such as C3S, C2S, C3A, C4AF, and gypsum needs to be given in detail, and the particle size distribution curve of the cement needs to be given.

Response 1: Thank you for pointing this out.

-          As we worked with standardised cements, the technical data sheet for each cement specifies its various characteristics. We thought it would be better to include the chemical composition of each cement rather than those required.

-          The particle size curve is clearly shown in Figure 1 (Particle size analysis of soils and cements) line 112.

-           

Comments 2: The third part is macro analysis, and the fourth part is micro analysis. The connection between macroscopic properties and microscopic properties requires some discussion.

Response 2: Thank you for pointing this out. Microscopic analysis provides a better justification for the results of macroscopic analysis. This is supported in line 454 to line 459 which states that the microscopic observation of pore reduction in formulations with CEM III 32.5 can explain from a macroscopic point of view why we have higher compressive strengths with CEM III 32.5 than with other binders.

Comments 3: There are no legends in Figures 12, 13, and 14, and legends need to be added.

Response 3: Thank you for pointing this out. This has been corrected in the article (Figures 12, 13 and 14).

Comments 4: At the end of the introduction, the original point of this article needs to be given in detail.

Response 4: Thank you for pointing this out. This has been corrected in the article (line 80 to line 96).

Comments 5: The title of Table 5 is Soil Concrete, but aggregate was not used in the study of this article. I suggest the author distinguish between cement paste, mortar, and concrete. All relevant places need to be checked.

Response 5: Thank you for pointing this out. In the case of soil concretes, the soil acts as the aggregate. We have one granular class for clayey sand (0/5) and two granular classes (0/5 and 0/10) for laterite.

Response to Reviewer 2 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Must be improved

Are all the cited references relevant to the research?

Must be improved

Is the research design appropriate?

Must be improved

Are the methods adequately described?

Can be improved

Are the results clearly presented?

Can be improved

Are the conclusions supported by the results?

Can be improved

3. Point-by-point response to Comments and Suggestions for Authors

MAJOR CONCERNS

Comments 1:  Extensive research has been performed on the topic. The authors do not add to the knowledge gap. Numerous papers on the topic can be found when one searches Google Scholar. The authors have not provided any discussion of the novelty of their research. The only sentence given by the authors is line 81 in the manuscript ("In the past, studies on soil concretes were much more limited to artificial soils but 81 also to underground structures"). This statement is incorrect and it does not serve as a novelty justification

Response 1: Thank you for pointing this out. This article deals with soil concrete and not soil-cement. The first work on this material was carried out in the IFSTAR laboratory, using a geotechnical approach on artificial soils (kaolinite, Fontainebleau sand, Triel sand, Fréjus sand, Archères sand). The binder used here was CEM III 32.5 C. The scientific work that followed was the theses of (Szymkiewicz, 2011) and (Guidmond-barrett, 2013) with several articles. Further work was carried out in the L2MGC laboratory following a concrete approach with the work of (Helson, 2017) who always worked on artificial soils (kaolinite, Fontainebleau sand) with CEM III 32.5 C cement as the binder and whose objective was to evaluate the influence of the clay content on the properties of the soil concrete. This was followed by the work of (Jacques Hessouh, 2021), who began working on reworked natural soils with CEM III 32.5 C as the binder, and whose objective was to compare the properties of soil concrete produced on site with that produced in the laboratory. The work in this article is carried out in the L2MGC laboratory and is a continuation of the work carried out by (Helson, 2017) and (Hessouh, 2021) on reworked natural soils (clayey sand and laterite) with CEM I 52.5 N, CEM II 42.5 R and CEM III 32.5 as binders. The aim of this study is to investigate the influence of the nature of the binder on the properties of the material.

Comments 2: The soils used in the research are exclusively located in Cameroon. How are these soils compared to other locations in the world? Are the results of this research of interest anywhere other than Cameroon? The results may only be of interest locally (Cameroon). Will this manuscript read by the general researcher in the world especially there are numerous articles published in this topic?

Response 2: Thank you for pointing this out.

-        The soils used in this work were subjected to a GTR classification, which is an internationally recognised soil classification. According to the classification, clayey sand and laterite are classified as A3, i.e. very plastic silty soils.

-        We encounter very plastic silty soils in France and just about everywhere else in the world, so yes, all the results of this research are of interest elsewhere than in Cameroon.

-        The results are not just of local interest (Cameroon).  All the soils and cements used were characterised and referenced against standards. This means that any soil in the world with the same classification can be used as a basis for the results.

-        This manuscript deals with the influence of the nature of the soil on the physical and mechanical properties of soil concretes. The concept of soil concrete, which is a material produced in-situ that consists of mixing the soil in place with a hydraulic binder and water, and whose applications are the improvement of soils for pavements and the construction of dykes. It is different from soil-cement, which has much more building applications.

Comments 3: How does the cement used compare with other cement produced in the world?

Response 3: Thank you for pointing this out. Standard NF EN 197-1 classifies cements into five types according to composition. In our study, we worked with three types of cement with the following characteristics:

-          CEM I 52.5 N consists of clinker with a content of between 95 - 100 % and secondary constituents of between 0 - 5 %. The chemical properties are given in table 3 (line 137).

-          CEM II 42.5 R consists of clinker with a content of between 65 - 94 % and other main constituents of between 6 - 35 %. The chemical properties are given in Table 3 (line 137).

-           CEM III 32.5 C consists of clinker with a content of between 5 - 64 % and other main elements of between 36 - 95 %. The chemical properties are given in Table 3 (line 137).

SPECIFIC COMMENTS

Comments 1: Soil Concrete is the terminology used in the manuscript. The traditional terminology is Soil Cement.

Response 1: Thank you for pointing this out. The terminology used in this article is "Soil concrete", which refers to in-situ concrete made from a mixture of soil, cement, and water. As a result, there is no excavation of aggregates (soil) and the soil in place is used to build the structures. There are two main methods: Soil Mixing, which is used for soil improvement, waterproofing and retaining walls, and Jet Grouting, where the fluid is injected under pressure, for example to build dykes. This is different from the term "Soil cement", which refers to earth concrete, which is used much more in buildings.

Comments 2: Why three different cements are used. Are they specified for different conditions?  Are there a differences between these three? If yes, what are they?

Response 2: Thank you for pointing this out.

-          Three cements are used because the aim of this article is to study the influence of the nature of the cement on the physical and mechanical properties of soil concretes based on sandy clay and laterite. We worked with three types of cement: CEM I 52.5, CEM II 42.5 and CEM III 32.5.

-          Yes, we have CEM III 32.5 C and CEM I 52.5 N produced in France by Calcia and Eqiom respectively. CEM II 42.5 R is produced in Cameroon by Cimencam, a subsidiary of the Lafarge group.

-          Yes, there is a difference between these three cements. They are specified in Table 3 (line 137) of the article.

-           

Comments 3: Lines 35 - 37. The authors state "On the one hand, it limits the destruction of the marine ecosystems from which the sediments used in concrete are extracted, reducing the multiplication of aggregate quarries and their abusive exploitation. On the other hand, it reduces the considerable carbon footprint of the transport of aggregates to the construction sites." The authors do not provide any data  to support the claims in these sentences. Additionally, these sentence argue against the use of cement. However, the researchers used cement. The reader will be confused with this contradiction. Additionally mentioning phrases like "abusive exploitation" is a highly politically charged phrase to which other people may disagree with. Such phrases do not belong in a technical paper.

Response 3: Thank you for pointing this out. We agree with this comment. Therefore, we have removed.

Comments 4: entence starting line 37. This statement is not true. Generally, we can confidently determine the strength of materials except for geomaterials.

Response 4: Thank you for pointing this out. The material studied here is soil concrete, which is a material produced in-situ from a mixture of soil, cement, and water. There is no excavation of the soil, and the binder and water are mixed or injected using equipment on the surface or at depth (Soil-mixing and Jet grouting). Depending on the depth or a linear surface, the variability of the layers and the heterogeneity of the soil mean that it is not always easy to predict the compressive strength of the material. This has been demonstrated by studies (Jacques Hessouh, 2021) which compared the mechanical properties (compressive strength) of a soil concrete made in the laboratory with one made on site.

Comments 5: Sentence starting line 39. It is not clear how many factors the authors are listing, 3, 4 or 5

Response 5: Thank you for pointing this out. there are 04 factors (well-founded comment). This has been corrected (line 37).

Comments 6: The two sentences starting line 41. These sentences appear very abruptly without any connection to the previous sentence. The second sentence provides the results of the study: "The results showed an increase compressive strength as a function of the cement content". This is very well known fact. It is nothing new.

Response 6: Thank you for pointing this out.

-          This has been corrected in the article (line 36 – 38).

-          We have removed the remark about the increase in compressive strength as a function of cement content.

-           

Comments 7: Line 51. What material is "this material"?

Response 7: Thank you for pointing this out. Soil concrete is the material. This has been corrected in the article (line 48).

Comments 8: Line 162. "...the 161 W/C ratio is chosen intuitively... ".  What is meant by intuitively? The W/C ration is a very important parameter in developing the strength of the soil cement. Arbitrary use of the W/C value can be very misleading.

Response 8: Thank you for pointing this out. The W/C ratio is chosen for values that allow a self-placing floor concrete to be achieved, i.e. a spread of between 32 and 33 cm. This has been corrected in the article (line 158 – 159)

Comments 9: Line 171. "After several spreading tests, the water content of the mixture is determined in accordance with the workability assumption". What is this assumption? What standard is used for this assumption?

Response 9: Thank you for pointing this out. The workability assumption is to obtain a self-placing floor concrete, i.e. a spread of between 32 and 33 cm. This is a recommendation, as there is as yet no standard on this subject for soil concretes.

Comments 10: Tables 5, 6 and 7. What is the moisture content of the soils used? The total moisture in the mixture is the total of the moisture present in the soil and the additional water added to the mix. Without knowing the moisture content of the soil, the W/C ratios cannot be accurately determined.

Response 10: Thank you for pointing this out. In our study, we pre-dry our soil samples for 24 hours in an oven at a temperature of 60°C until a constant mass is obtained.

Response to Reviewer 1 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Yes

Are all the cited references relevant to the research?

Yes

Is the research design appropriate?

Yes

Are the methods adequately described?

Yes

Are the results clearly presented?

Yes

Are the conclusions supported by the results?

Yes

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: Abstract: the abstract should summarise the main points and avoid unnecessary parts for better understanding and readability. -Please highlight the scientific value added in the abstract. Add some of the most critical quantitative results to the abstract.

Response 1: Thank you for pointing this out. The abstract of this paper is effectively all the suggestions made.

Comments 2: The quotation should be revised. Refer to the most recent and relevant references.

Response 2: Thank you for pointing this out. We agree with this comment. Therefore, we have revised and standardised all the quotations in the article. We also relied on recent and relevant references on the subject. For example, those of (Hessouh et al., 2023), (33. X. Guo et al., 2022) and (Helson et al., 2018) which are referenced 20, 33 and 30.

Comments 3: Avoid unnecessary and repetitive sentences.

Response 3: Thank you for pointing this out. After checking the text of the article, there are no unnecessary or repetitive sentences.

Comments 4: Before using an abbreviation, the full term must be explained in the text.

Response 4: Thank you for pointing this out. After revising the article, the full term is explained in the text before each abbreviation.

Comments 5: Did the authors measure the additional second C-S-H gels? As we all know, pozzolanic materials react with Ca(OH)2. They produce second C-S-H gels... Please explain fully ? It is also very important to know the curing time after 90 days or more ? Do reactions occur over the long term ? Please explain fully ?

Response 5: Thank you for pointing this out.

-        The second additional C-S-H gels were not measured, as this article did not dwell on the chemical aspects (XRD, EDX) of the material. We focused much more on the physical and mechanical aspects.

-        The reaction between Portlandite produced by cement hydration and the Si and Al in the soil is known as the pozzolanic reaction (Porbaha et al. 2000). The hydrated calcium silicates (CSH) formed from kaolinite are mono- and dicalcium hydrates (Khay, 2012) which structurally correspond to an imperfect form of tobermorite and jennite (Taylor, 1997). These CSH have a reticular structure (Locat et al. 1990) that can be used as an indicator of durability (Kamruzzaman et al. 2011). In kaolinite, the calcium aluminate formed is tricalcium, and a second gel is also formed, C-S-A-H, which has a lamellar structure (Locat et al. 1990).

-        In this article, the study was carried out for a 90-days period. However, compressive strength seems to stabilise at around 180 days.

-        On contact with water, an amorphous aluminate-rich gel and ettringite nuclei are formed in the short term (Taylor, 1997). Then, the calcium in solution gradually increases and the C3S react with the water to form an 'impermeable' layer of calcium silicates (CSH) on the surface of the grains. The quantity of CSH formed is preponderant, that of ettringite low, and all the Portlandite is consumed by the formation of CSH (Lothenbach et al. 2011). However, the hydrate layer around the anhydrous cement grains thickens more slowly and illustrates the difference in attack processes between slag and clinker, which is responsible for the initially slower development of mechanical strength (Van Rompaey, 2006).

Response to Reviewer 2 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Must be improved

Are all the cited references relevant to the research?

Must be improved

Is the research design appropriate?

Must be improved

Are the methods adequately described?

Can be improved

Are the results clearly presented?

Can be improved

Are the conclusions supported by the results?

Can be improved

3. Point-by-point response to Comments and Suggestions for Authors

MAIN CONCERNS

Comments 1: Extensive research has been carried out on the subject. The authors add nothing to the lack of knowledge. Numerous articles on the subject can be found by searching Google Scholar. The authors have not provided any discussion of the novelty of their research. The only sentence given by the authors is line 81 of the manuscript ("In the past, studies on soil concretes were much more limited to artificial soils but also to underground structures"). This statement is incorrect and does not constitute a justification of the novelty.

Response 1: Thank you for pointing this out. This article deals with soil concrete and not earth concrete. The first work on this material was carried out in the IFSTAR laboratory, using a geotechnical approach on artificial soils (kaolinite, Fontainebleau sand, Triel sand, Fréjus sand, Archères sand). The binder used here was CEM III 32.5 C. The scientific work that followed was the theses of (Szymkiewicz, 2011) and (Guidmond-barrett, 2013) with several articles. Further work was carried out in the L2MGC laboratory following a concrete approach with the work of (Helson, 2017) who always worked on synthetic soils with CEM III 32.5 C cement as the binder and whose objective was to evaluate the influence of the clay content on the properties of the soil concrete. This was followed by the work of (Jacques Hessouh, 2021), who began working on reworked natural soils with CEM III 32.5 C as the binder, and whose objective was to compare the properties of soil concrete produced on site with that produced in the laboratory. The work in this article is carried out in the L2MGC laboratory and is a continuation of the work carried out by (Helson, 2017) and (Hessouh, 2021) on reworked natural soils (clayey sand and laterite) with CEM I 52.5 N, CEM II 42.5 R and CEM III 32.5 as binders. The aim of this study is to investigate the influence of the nature of the binder on the properties of the material.

Comments 2: The soils used in the research are located exclusively in Cameroon. How do these soils compare with other parts of the world ? Are the results of this research of interest elsewhere than in Cameroon ? The results can only be of interest locally (Cameroon). Will this manuscript be read by the general researcher in the world, especially as there are many articles published on this subject ?

Response 2: Thank you for pointing this out.

-        The soils used in this work were subjected to a GTR classification, which is an internationally recognised soil classification. According to the classification, clayey sand and laterite are classified as A3, i.e. very plastic silty soils.

-        We encounter very plastic silty soils in France and just about everywhere else in the world, so yes, all the results of this research are of interest elsewhere than in Cameroon.

-        The results are not just of local interest (Cameroon).  All the soils and cements used were characterised and referenced against standards. This means that any soil in the world with the same classification can be used as a basis for the results.

-        This manuscript deals with the influence of the nature of the soil on the physical and mechanical properties of soil concretes. The concept of soil concrete, which is a material produced in-situ that consists of mixing the soil in place with a hydraulic binder and water, and whose applications are the improvement of soils for pavements and the construction of dykes, is different from that of earth concrete, which has much more building applications.

Comments 3: How does the cement used compare with other cements produced around the world ?

Response 3: Thank you for pointing this out. Standard NF EN 197-1 classifies cements into five types according to composition. In our study, we worked with three types of cement with the following characteristics:

-          CEM I 52.5 N consists of clinker with a content of between 95 - 100 % and secondary constituents of between 0 - 5 %. These chemical properties are given in table 3.

-          CEM II 42.5 R consists of clinker with a content of between 65 - 94 % and other main constituents of between 6 - 35 %. These chemical properties are given in Table 3.

-           CEM III 32.5 C consists of clinker with a content of between 5 - 64 % and other main elements of between 36 - 95 %. These chemical properties are given in Table 3.

SPECIFIC COMMENTS

Comments 1: Soil Concrete is the terminology used in the manuscript. The traditional terminology is Soil Cement.

Response 1: Thank you for pointing this out. The terminology used in this article is "Soil concrete", which refers to in-situ concrete made from a mixture of soil, cement, and water. As a result, there is no excavation of aggregates (soil) and the soil in place is used to build the structures. There are two main methods: Soil Mixing, which is used for soil improvement, waterproofing and retaining walls, and Jet Grouting, where the fluid is injected under pressure, for example to build dykes. This is different from the term "Soil cement", which refers to earth concrete, which is used much more in buildings.

Comments 2: Why are three different cements used? Are they specified for different conditions ? Are there any differences between these three ? If so, what are they ?

Response 2: Thank you for pointing this out.

-          The main studies on floor concrete have been carried out using CEM III 32.5 C, which is a slag cement made up of 85% slag and 15% clinker. However, slag cements are derived from steel products, the reserves of which are disappearing these days. This special and rare cement is not produced in many countries in Europe, Africa, and Asia. The aim of this work is to study the influence of the type of cement on the physical and mechanical properties of soil concretes. To do this, we considered two types of soil, clayey sand, and laterite. The aim is to provide companies such as Spie Fondations or Sol Etanche Bachy, who are implementing this technology, with information (decision-support tools) in the event of this binder becoming unavailable in a particular area or part of the working world.

-          Yes, we have CEM III 32.5 C and CEM I 52.5 N produced in France by Calcia and Eqiom respectively. CEM II 42.5 R is produced in Cameroon by Cimencam, a subsidiary of the Lafarge group.

-          Yes, there is a difference between these three cements. They are specified in Table 3 of the article.

Comments 3: Lines 35 to 37. The authors state: "On the one hand, it limits the destruction of marine ecosystems from which the sediments used in concrete are extracted, thus reducing the multiplication of aggregate quarries and their abusive exploitation ... it reduces the considerable carbon footprint of transporting aggregates to construction sites. The authors provide no data to support the claims made in these sentences. Furthermore, these sentences argue against the use of cement. However, the researchers did use cement. The reader will be confused by this contradiction. Furthermore, mentioning expressions such as "abusive exploitation" is a highly politically charged expression with which others may disagree. Such expressions have no place in a technical document.

Response 3: Thank you for pointing this out. We agree with this comment. Therefore, we have removed in the manuscript

Comments 4: Sentence beginning on line 37. This statement is not true. Generally, we can determine the strength of materials with complete confidence, except for geomaterials.

Response 4: Thank you for pointing this out. The material studied here is soil concrete, which is a material produced in-situ from a mixture of soil, cement, and water. There is no excavation of the soil, and the binder and water are mixed or injected using equipment on the surface or at depth (Soil-mixing and Jet grouting). Depending on the depth or a linear surface, the variability of the layers and the heterogeneity of the soil mean that it is not always easy to predict the compressive strength of the material. This has been demonstrated by studies (Jacques Hessouh, 2021) which compared the mechanical properties (compressive strength) of a soil concrete made in the laboratory with one made on site.

Comments 5: Sentence beginning on line 39. It is not clear how many factors the authors list, 3, 4 or 5.

Response 5: Thank you for pointing this out. there are 04 factors (well-founded comment). This has been corrected.

Comments 6: The two sentences starting on line 41. These sentences appear very abruptly without any link to the previous sentence. The second sentence presents the results of the study: "The results showed an increase in compressive strength as a function of cement content". This is a well-known fact. It's nothing new.

Response 6: Thank you for pointing this out.

-          Babasaki et al [5] carried out a study on soil concretes where the soil was an organic soil and the results showed that four main factors influence the strength of soil concrete: the characteristics of the binder, the nature of the soil encountered, the mixing and curing conditions.

-          We have removed the remark about the increase in compressive strength as a function of cement content.

Comments 7: Line 51. What material is "this material" ?

Response 7: Thank you for pointing this out. Soil concrete as a material.

Comments 8: Line 162: "...the 161 E/C ratio is chosen intuitively. ... " . What is meant by "intuitively" ? The W/C ratio is a very important parameter in the development of soil cement strength. The arbitrary use of the W/C value can be very misleading.

Response 8: Thank you for pointing this out. The W/C ratio is chosen for values that allow a self-placing floor concrete to be achieved, i.e. a spread of between 32 and 33 cm.

Comments 9: Line 171: "After several spreading trials, the water content of the mixture is determined in accordance with the workability assumption". What is this assumption? What standard is used for this assumption ?

Response 9: Thank you for pointing this out. The workability assumption is to obtain a self-placing floor concrete, i.e. a spread of between 32 and 33 cm. recommendation

Comments 10: Tables 5, 6 and 7. What is the moisture content of the soils used? The total moisture content of the mix is the sum of the moisture present in the soil and the additional water added to the mix. Without knowing the moisture content of the soil, the W/C ratios cannot be accurately determined.

Response 10: Thank you for pointing this out. In our study, we pre-dry our soil samples for 24 hours in an oven at a temperature of 60°C jusquà masse constate.

Response to Reviewer 3 Comments

1. Summary

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions/corrections highlighted/in track changes in the re-submitted files.

2. Questions for General Evaluation

Reviewer’s Evaluation

Response and Revisions

Does the introduction provide sufficient background and include all relevant references?

Can be improved

Are all the cited references relevant to the research?

Can be improved

Is the research design appropriate?

Can be improved

Are the methods adequately described?

Can be improved

Are the results clearly presented?

Can be improved

Are the conclusions supported by the results?

Can be improved

3. Point-by-point response to Comments and Suggestions for Authors

Comments 1: For cement, the content of mineral components such as C3S, C2S, C3A, C4AF and gypsum must be indicated in detail, together with the cement's particle size distribution curve.

Response 1: Thank you for pointing this out.

-          Mineral components have not been assessed. ????

-          The particle size curve is clearly shown in Figure 1 (Particle size analysis of soils and cements).

Comments 2: The third part is macro-analysis and the fourth part is micro-analysis. The link between macroscopic and microscopic properties requires some discussion.

Response 2: Thank you for pointing this out. Link given from line 454 to line 459. Because the results of the microscopic analysis are closely in line with the results of the macroscopic analysis. Because the reduction of pores in formulations with CEM III 32.5 can explain why we have higher compressive strengths with CEM III 32.5 than with other binders.

Comments 3: Figures 12, 13 and 14 have no captions and captions need to be added.

Response 3: Thank you for pointing this out. Well-founded comment (It has been incorporated)

Comments 4: At the end of the introduction, the initial point of this article should be detailed.

Response 4: Thank you for pointing this out. This is done from line 80 to line 96.

Comments 5: The title of Table 5 is Soil Concrete, but aggregates were not used in the study of this article. I suggest that the author distinguish between cement paste, mortar, and concrete. All relevant places should be checked.

Response 5: Thank you for pointing this out. In the case of soil concretes, the soil acts as the aggregate. We have one granular class for clayey sand (0/5) and two granular classes (0/5 and 0/10) for laterite.