Quantitative Analysis of Bound Water Content in Marine Clay and Its Influencing Factors During the Freezing Process by Nuclear Magnetic Resonance

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Reviewer Blind Comments to Author:

The research article (jmse-3497908-peer-review-v1) investigates the effect of water content in the marine clay with the help of nuclear magnetic resonance technique. The quantitative analysis of bound water content in marine clay is based on the temperature effect during the freezing processes. The study presented in this article is very useful to understand the geological problems for laying foundation of engineering constructions and development of infrastructure over reclamation of marine soft clay rich soils. Thus, this study is most suitable for publication in the Journal of Marine Science and Engineering.

However, some major limitations are observed in this draft of the article that required carefully with great attention on detail re-organization to meet the publication standard of the Journal of Marine Science and Engineering.

Abstract: Some sentences in the Abstract are very long and no clear meaning observed. This part of the Abstract need very careful re-writing into small and meaningful sentences. Some rectifications as well as recommendations have been suggested in the pdf file.

There are several limitations has been observed in this present draft of the article that needs thoughtful reorganization. Some highlighted problems need to be clarified with appropriate description and needs to be explained as follows:

1. What do you mean by bound water?
2. How can you relate the creep behaviour in clay with quantity of bound water of clay particles? (Page 2)
3. What is unfrozen water content in the soil? How this term “unfrozen” is useful? You can simply use “water content”.
4. Define use of FID signal of NMR in this study? (Page 3)
5. What do you mean by unfrozen water content?
6. What do you mean by “free water has nearly frozen?” You can replace “frozen water” by “ice”.
7. What do you mean by lower thermodynamic potential energy of water? Why there is difference in bound water and capillary water and free water? (Page 6)
8. Why bound water is affected by the electrostatic attraction on the surface of soil particles?
9. What is mucky clay?
10. What kind of organic matter present in your samples?

 

 

Citation of reference in the manuscript needs to be correct as per the style of the Journal of Marine Science and Engineering.

 

In major part of the draft manuscript, sentences are too long and carelessly written. This is crucial to be re-phrased into small and meaningful sentences. It is also advised to re-write meaningful English sentence considering the structure of English grammar. Frequent grammatical mistakes and errors has been observed in this manuscript, which required improvements and re-organization of sentences that are stated in the main article as a comment. Therefore, all points should be considering before submission of your revised version of the manuscript.

I observed, this manuscript is original and suitable to recommend for publication in the Journal of Marine Science and Engineering with minor revision.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Citation of reference in the manuscript needs to be correct as per the style of the Journal of Marine Science and Engineering.

The research article needs re-organization with re-writing particularly in case of English sentence structures. There are very long sentences with no clear meaning, which is very difficult to diagnose the scientific meanings. Some English words are confusing like “unfrozen water” which can be replaced by “water”. Also “frozen water” can be replaced by “ice”. I observed unsteadily grammars and stylistic errors in the manuscript, which even make reading of the manuscript very hard. I have tried to make some suggestions (see edited attached annotated file).

Author Response

Dear Reviewer,

Thank you for your kind reviews of our manuscript entitled “Quantitative analysis of bound water content in marine clay and its influencing factors during the freezing process by nuclear magnetic resonance”. Special thanks to your good comments and suggestions, and we are deeply impressed by your conscientious, rigorous, high–efficiency and responsible attitude towards the evaluation work. These comments are all valuable and very helpful for revising and improving our paper.

Under the guidance your comments, we have carefully and extensively revised and polished our manuscript. Revisions in the paper have been marked in red. Revisions for the English language have been marked in green. We hope that the corrections will meet with approval and look forward to hearing from you for any further consideration. A point–to–point response is provided below.

 

The research article (jmse-3497908-peer-review-v1) investigates the effect of water content in the marine clay with the help of nuclear magnetic resonance technique. The quantitative analysis of bound water content in marine clay is based on the temperature effect during the freezing processes. The study presented in this article is very useful to understand the geological problems for laying foundation of engineering constructions and development of infrastructure over reclamation of marine soft clay rich soils. Thus, this study is most suitable for publication in the Journal of Marine Science and Engineering.

However, some major limitations are observed in this draft of the article that required carefully with great attention on detail re-organization to meet the publication standard of the Journal of Marine Science and Engineering.

Response: Thank you very much for your affirmation of our work. Your affirmation has greatly supported us in this study, and your comments are very helpful to improve the level of the manuscript. We also recognize the inadequacy of the paper and have made detailed changes based on your suggestions. We will answer your questions one-on-one.

 

Comments in pdf file: Abstract: Some sentences in the Abstract are very long and no clear meaning observed. This part of the Abstract need very careful re-writing into small and meaningful sentences. Some rectifications as well as recommendations have been suggested in the pdf file.

Response: Thank you very much of your professional comments. We are deeply aware of the shortcomings of the abstract and other parts of the paper, and we apologize for any inconvenience in reading. Based on your valuable suggestions, we have revised the abstract and other parts of the paper carefully. We will present our revisions one-on-one.

 

Comments in pdf file for the English language:

Re-write this section into two meaningful sentence. “ Further, this study illustrated the effect of soil such as organic matter content, soluble salt content, and cation exchange capacity on the bound water content, and the differences in the soil microstructure lead to a lack of strict positive correlation between clay content and bound water content.”

Response: Thank you very much for your helpful comment on the Abstract. We have carefully revised the Abstract, and break long sentences into shorter ones. The revisions are as below:

Line 11-22, page 1.

Abstract The change in bound water content with temperature is a core issue in studying temperature effects in clayey soils. This study used nuclear magnetic resonance (NMR) techniques to measure pore water in three types of marine clay, ranging from inland to coastal areas. The T₂ cutoff values were proposed to distinguish between bulk water, capillary water and bound water, the curves of unfrozen water and bound water content with changing temperatures were obtained during the freezing process. Additionally, the impact of soil properties on bound water content was analyzed. The research findings indicated that the pore water in marine clay is dominated by bound water, and the change of bound water content with temperature in each soil layer can be divided into four stages: the trace phase change stage, the intense phase change stage, the transitional phase change stage, and the stabilizing stage. Further, the effect of soil properties such as organic matter content, soluble salt content, and cation exchange capacity on bound water content was illustrated, and clay content and bound water content were found not to be strictly positively correlated. 

 

Very long sentence....

No clear meaning...

Re-write into small sentences.

“Therefore, in the study of clay, starting from the perspective of bound water, determining the boundary values of different types of bound water in the soil can help to explore the hydration mechanism of clay, which can provide a theoretical basis for the improvement of marine soft clay soil foundations, and can also play a protective role for geotechnical engineering”

Response: Thank you very much for your helpful comment on the Introduction. We have carefully rewritten the sentences and broken long sentences into shorter ones. The revisions are as below:

Line 38-40, page 1.

Therefore, determining the boundary values of different kinds of pore water in soil not only helps to explore the hydration mechanism of clay, but also plays a protective role in geotechnical engineering. 

 

Why term "unfrozen" is used here? 

“To investigate the influencing factors of unfrozen water content in the soil, this paper selected three locations for sampling work from inland to the coastal direction in Chong-ming Island, Shanghai”

Response: Thank you very much for your helpful question on the Introduction. We apologize for the mistake we have made. We have carefully revised the sentence and replaced “unfrozen water” with “bound water”. The revisions are as below:

Line 95-97, page 2.

To study the factors affecting bound water content in the soil, this paper selected three locations for sampling work from inland to the coastal direction in Chongming Island, Shanghai.

 

Define FID? 

“In this process, the 1H population produces a gradually decaying oscillation signal, which is the FID signal.”

Response: Thank you very much for your question on the section 2.1. NMR method. We apologize for any inconvenience in reading. In the paper we have explained the origin of FID signals and curves, we have also defined FID as “free induction decay”.

The exact location is in lines 112-114, page 3 of the text.

In this process, the ¹H population produces a gradually decaying oscillation signal, which is the FID signal. This signal oscillates with a sinusoidal law and decays with an exponential law, thus forming a curve known as the free induction decay (FID) curve.

 

Define....?

“Determination of T₂ cutoff values for different types of unfrozen water in soils”

Response: Thank you very much for your kind question on the title of section 3.1. After careful consideration, we changed the “unfrozen water” to “pore water”. Because the T₂ cutoff values in this section were proposed based on the NMR method. The NMR method measures the amount of unfrozen pore water in the soil during freezing and determines the types of pore water based on the magnitude of the T₂. Therefore, the T₂ cutoff values although distinguishe between the types of unfrozen water in the freezing process, the unfrozen water belongs to the pore water, so we changed the “unfrozen water” to “pore water” in the title and some other places of this section.

The revisions are as below:

Lines 158-162, pages 4-5.

3.1. Determination of T₂ cutoff values for different types of pore water in soils

In order to investigate the content and variations of different kinds of pore water in soil, it is important to determine cutoff points between the components. T₂ can be used as an important indicator in NMR test to differentiate between different types of pore water in the soil. 

 

Confusing statement....

Re-write this into meaningful sentence.

“at this stage, most free water has nearly frozen and weakly bound water begins to freeze.”

Response: Thank you very much for your constructive suggestion on section 3.1. We have rewritten the sentence according to your suggestion. We have replaced “free water” with “bulk water”, and removed the “nearly”. We also changed “weakly bound water” to “LBW”. LBW is loosely bound water, which was mentioned in the previous text. The revisions are as below:

Lines 190-192, page 6.

As the temperature continuously decreases from -3°C to -7°C, the peak area decreases slowly, at this stage, most bulk water has frozen into ice and LBW begins to freeze. 

 

Not clear...

Explain

“lower thermodynamic potential energy and freezing point of bound water”

Response: Thank you very much for your kind suggestion on section 3.1. We apologize for the mistake we have made, bound water has higher thermodynamic potential energy and lower freezing point than capillary water and bulk water. We have also added explanations according to your suggestion. The revisions are as below:

Lines 198-208, page 6.

The surface of soil particles generally carries negative charges and these negative charges create an electric field around the soil particles. Polar water molecules can be attracted and oriented by the charges on the surface of the soil particles. Therefore, when water molecules are close to the surface of the negatively charged soil particles, they are attracted by the electrostatic force of the electric field, and the closer the distance, the stronger the electrostatic force. The distance between the bound water and the soil particles is short, so the bound water is tightly adsorbed on the surface of the soil particles by the electrostatic force. This kind of force makes the molecular arrangement of the bound water orderly and with high thermodynamic potential energy. From the perspective of melting, compared to capillary water and bulk water, bound water in micropores with higher thermodynamic potential energy and lower freezing point melts first.

 

Why....?

“Since the bound water is affected by the electrostatic attraction on the surface of soil particles,”

Response: Thank you very much for your question on section 3.4. In conjunction with your last question, we have made changes and given specific explanations. The revisions are as below:

Lines 198-203, page 6.

The surface of soil particles generally carries negative charges and these negative charges create an electric field around the soil particles. Polar water molecules can be attracted and oriented by the charges on the surface of the soil particles. Therefore, when water molecules are close to the surface of the negatively charged soil particles, they are attracted by the electrostatic force of the electric field, and the closer the distance, the stronger the electrostatic force. 

 

Very long sentence....

No clear meaning...

Needs to be re-phrased into small sentence

“Combined with the bound water fractions of each soil layer in Fig. 12(b), it can be seen that the mucky clay layer has the highest bound water fraction, followed by the clay layer, and the silty clay layer has the lowest bound water fraction, Fig. 12(a) and Fig. 12(b) present inconsistent patterns, so it can be inferred that the soluble salt content is not the key factor influencing the bound water content in different type of soils.”

“However, in the same soil layer, the bound water fraction of soil samples and the total amount of soluble salts show a strong linear relationship, which indicates that within a certain range, the increase of soluble salts in the soil leads to more ions entering into the diffusion layer, and the diffusion layer becomes thicker, resulting in a thickening of the bound water film adsorbed by 428

the soil particles.”

“The precipitated crystallized salt adheres to the soil particles or fills in the pores of the soil, resulting in a decrease in the content of large pores and an increase in the content of small pores, and a higher content of bound water existing in the small pores.”

Response:Thank you very much for your helpful comments on the section 3.5.2. We have carefully revised these sentences, and break long sentences into shorter ones. The revisions are as below:

Lines 429-434, page 13.

Combined with the bound water fractions of each soil layer in Fig. 12(b), the highest bound water fraction is found in mucky clay layer, followed by the clay layer, and the lowest bound water fraction is found in silty clay layer. Fig. 12(a) and Fig. 12(b) present inconsistent patterns, so it can be inferred that the content of soluble salt is not a key factor influencing the content of bound water in different type of soils.

Lines 434-438, page 13.

However, in the same soil layer, the bound water fraction of soil samples and the total amount of soluble salts show a strong linear relationship. It indicates that within a certain range, increased soluble salt content in the soil leads to more ions entering the diffusion layer. Therefore, the bound water film becomes thicker.

Lines 442-445, page 13.

The precipitated crystallized salt adheres to the soil particles or fills in the pores of the soil, thus, the amount of large pores decreases and the amount of small pores increases. In addition, more bound water exists in small pores. 

 

very long sentence...

No clear meaning...

Needs to be re-phrased into small sentence

“In clay and silty clay layers, the cation content is positively correlated with the bound water fraction, this is because the exchangeable cations will adsorb water molecules around them to form a diffusion layer, the greater the amount of exchangeable cations, the thicker the diffusion layer will be, resulting in a higher bound water content.”

“This may be due to the high concentration of cations in the silty clay, the ion concentration in the diffusion layer is saturated, and when the ion concentration continues to increase, some of the ions in the diffusion layer enter the fixed layer, resulting in the thinning of the diffusion layer and the reduction of the bound water content.”

Response: Thank you very much for your helpful comments on the section 3.5.3. We have carefully revised these sentences, and break long sentences into shorter ones. The revisions are as below:

Lines 474-477, page 15.

In clay and silty clay layers, the cation content is positively correlated with the bound water fraction, this is because the exchangeable cations will adsorb water molecules around them to form a diffusion layer. Therefore, the greater the amount of exchangeable cations, the thicker the diffusion layer, and the higher the bound water content.

Lines 479-483, page 15.

This may be due to the high concentration of cations in the silty clay, the ion concentration in the diffusion layer is saturated. When the ion concentration continues to increase, some of the ions enter the fixed layer from the diffusion layer, thus the diffusion layer becomes thinner and the bound water content begins to decrease.

 

 

Report comments online: There are several limitations has been observed in this present draft of the article that needs thoughtful reorganization. Some highlighted problems need to be clarified with appropriate description and needs to be explained as follows:

Response: We recognize the inadequacy of the paper and have made detailed changes based on your suggestions. We will answer your questions one-on-one.

Comment 1: What do you mean by bound water?

Response: Thank you very much for your question. We have added descriptions of bound water in the Introduction. The revisions are as below:

Lines 42-45, pages 1-2.

Water attracted to the surface of soil particles by the electrostatic force called bound water  According to the distance and the interaction forces between water and soil particles, bound water can further be classified into loosely bound water (LBW) and tightly bound water (TBW).

 

Comment 2: How can you relate the creep behaviour in clay with quantity of bound water of clay particles? (Page 2)

Response: Thank you very much for your question. The explanations are as below:

The existence of bound water increases the viscous interaction between soil particles, and creep behavior occurs when the soil is subjected to external loading. The higher the content of bound water, the stronger the viscous interaction and the more significant the creep behavior.

 

Comment 3: What is unfrozen water content in the soil? How this term “unfrozen” is useful? You can simply use “water content”.

Response: Thank you very much for your questions! Unfrozen water refers to the pore water in the soil that has not yet frozen during the freezing process, and it belongs to pore water. However, this paper discussed the changing behavior of pore water in the soil during the freezing process, which involves the changing content of unfrozen water, so I think it is necessary to keep the term “unfrozen water”. But in some sections that do not involve the change of temperature (Introduction and section 3.1), we have replaced unfrozen water with pore water.

 

Comment 4: Define use of FID signal of NMR in this study? (Page 3)

Response: Thank you very much for your kind suggestion. We apologize for any inconvenience in reading. In the paper we have explained the origin of FID signals and curves, we have also defined FID as “free induction decay”. We also mentioned that the FID curve can be inverted into a T₂ distribution curve, which in turn obtains the T₂ value.

The exact location is in lines 112-118, page 3 of the text.

In this process, the ¹H population produces a gradually decaying oscillation signal, which is the FID signal. This signal oscillates with a sinusoidal law and decays with an exponential law, thus forming a curve known as the free induction decay (FID) curve. The time required for the macroscopic magnetization intensity to decrease to zero in the direction perpendicular to the static magnetic field during this process is known as the transverse relaxation time (T₂). Therefore, the FID signal is closely related to T₂, and the FID curve can be transformed by Fourier transformation to generate T₂ distribution curves.

 

Comment 5: What do you mean by unfrozen water content?

Response: Thank you very much for your question! Unfrozen water content refers to the content of pore water in the soil that has not yet frozen during the freezing process, and unfrozen water belongs to pore water.

 

Comment 6: What do you mean by “free water has nearly frozen?” You can replace “frozen water” by “ice”.

Response: Thank you very much for your question and suggestion! In conjunction with your questions in pdf file, we have rewritten the sentence according to your suggestion. We have replaced “free water” with “bulk water”, and removed the “nearly”. We also changed “weakly bound water” to “LBW”. LBW is loosely bound water, which was mentioned in the previous text. The revisions are as below:

Lines 190-192, page 6.

As the temperature continuously decreases from -3°C to -7°C, the peak area decreases slowly, at this stage, most bulk water has frozen into ice and LBW begins to freeze. 

 

Comment 7: What do you mean by lower thermodynamic potential energy of water? Why there is difference in bound water and capillary water and free water? (Page 6)

Response: Thank you very much for your questions! We apologize for the mistake we have made, bound water has higher thermodynamic potential energy and lower freezing point than capillary water and bulk water. We have also added explanations according to your suggestion. The revisions are as below:

Lines 198-208, page 6.

The surface of soil particles generally carries negative charges and these negative charges create an electric field around the soil particles. Polar water molecules can be attracted and oriented by the charges on the surface of the soil particles. Therefore, when water molecules are close to the surface of the negatively charged soil particles, they are attracted by the electrostatic force of the electric field, and the closer the distance, the stronger the electrostatic force. The distance between the bound water and the soil particles is short, so the bound water is tightly adsorbed on the surface of the soil particles by the electrostatic force. This kind of force makes the molecular arrangement of the bound water orderly and with high thermodynamic potential energy. From the perspective of melting, compared to capillary water and bulk water, bound water in micropores with higher thermodynamic potential energy and lower freezing point melts first.

 

Comment 8: Why bound water is affected by the electrostatic attraction on the surface of soil particles?

Response: Thank you very much for your questions! In conjunction with your last question, we have made changes and given specific explanations. The revisions are as below:

Lines 198-203, page 6.

The surface of soil particles generally carries negative charges and these negative charges create an electric field around the soil particles. Polar water molecules can be attracted and oriented by the charges on the surface of the soil particles. Therefore, when water molecules are close to the surface of the negatively charged soil particles, they are attracted by the electrostatic force of the electric field, and the closer the distance, the stronger the electrostatic force. 

 

Comment 9: What is mucky clay?

Response: Thank you very much for your question! Soils that exhibit a fluid-plastic or soft-plastic state and have a natural pore ratio between 1.0 and 1.5 are known as mucky clays.

 

Comment 10: What kind of organic matter present in your samples?

Response: Thank you very much for your question! The organic matter in marine clay is mainly composed of humic substances, including plant and animal residues, microorganisms and their metabolites. We also added the explanation in the paper.

Lines 402-403, page 12.

The organic matter in marine clay is mainly composed of humic substances, including plant and animal residues, microorganisms and their metabolites. 

 

Comment: Citation of reference in the manuscript needs to be correct as per the style of the Journal of Marine Science and Engineering.

Response: Thank you very much for your helpful suggestion! We have revised the citation style according to your suggestion.

 

Comments on the Quality of English Language:

Citation of reference in the manuscript needs to be correct as per the style of the Journal of Marine Science and Engineering.

Response: Thank you very much for your helpful suggestion! We have revised the citation style according to your suggestion.

 

The research article needs re-organization with re-writing particularly in case of English sentence structures. There are very long sentences with no clear meaning, which is very difficult to diagnose the scientific meanings. Some English words are confusing like “unfrozen water” which can be replaced by “water”. Also “frozen water” can be replaced by “ice”. I observed unsteadily grammars and stylistic errors in the manuscript, which even make reading of the manuscript very hard. I have tried to make some suggestions (see edited attached annotated file).

Response: Thank you very much for your helpful suggestions! We also recognize the inadequacy of the paper and have made detailed changes based on your suggestions. We have answered your questions one-on-one before.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study is related to a study on the changes in adsorbed water content with temperature in the study of temperature effects in clay soils. The study used Nuclear Magnetic Resonance (NMR) technology to measure the amount of unfrozen water in three different types of marine clays, ranging from inland to coastal areas. The research findings showed that pore water in marine clay is largely dominated by bound water, and the bound water content changing with temperature in each soil layer can be studied in four stages.

According to my initial assessment, the article is well structured and has the potential to contribute to the literature. Therefore, I think that the article can be accepted after some revision. Some corrections given below may be applied before its acceptance:

1. It is unclear whether repeated measurements were made on the same samples in the manuscript, and information on the consistency and standard deviations of the results is not provided. The lack of repeatability data makes it difficult to assess the reliability of the findings. In addition, critical experimental parameters such as the initial water content and density of the samples were not explicitly controlled. This lack raises concerns about the repeatability and accuracy of the experimental results. The authors are advised to:

 

*Perform repeated measurements to ensure reliability and consistency of the results.

*Report standard deviations and variability in measurements.

*Clearly define the initial water content and density control to increase experimental repeatability.

 

2. Microstructural analysis using SEM images is limited to qualitative observations and cannot provide a quantitative assessment. In particular, important parameters such as pore size distribution, specific surface area, and particle shape factors are not calculated. The lack of these quantitative measurements limits the verification of the relationship between microstructure and bound water content. Authors are encouraged to:

 

*Perform quantitative image analysis using advanced techniques (e.g. ImageJ or MATLAB) to calculate pore size distribution, specific surface area, and particle shape factors.

 

*Relate quantitative microstructural parameters to bound water content to support proposed mechanisms.

 

3. The manuscript does not adequately compare its findings to the existing literature on bound water content and freeze-thaw cycles. In particular, recent work on thermodynamic phase change models and microstructure-water interactions is ignored. This weakens the contribution of the manuscript to the literature and raises questions about its claim to novelty. To strengthen the impact and relevance of the work, authors should:

 

*Include a comprehensive literature review that situates the work in the context of recent developments in thermodynamic modeling and microstructure-water interactions.

*Compare the results with findings from recent studies to highlight the contributions and limitations of the current work.

*Discuss the implications of the findings in the context of existing models and theories.

Author Response

Dear Reviewer,

Thank you for your kind reviews of our manuscript entitled “Quantitative analysis of bound water content in marine clay and its influencing factors during the freezing process by nuclear magnetic resonance”. Special thanks to your good comments and suggestions, and we are deeply impressed by your conscientious, rigorous, high–efficiency and responsible attitude towards the evaluation work. These comments are all valuable and very helpful for revising and improving our paper.

Under the guidance your comments, we have carefully and extensively revised and polished our manuscript. Revisions in the paper have been marked in red. We hope the corrections will meet with approval and look forward to hearing from you for further consideration. A point–to–point response is provided below.

 

This study is related to a study on the changes in adsorbed water content with temperature in the study of temperature effects in clay soils. The study used Nuclear Magnetic Resonance (NMR) technology to measure the amount of unfrozen water in three different types of marine clays, ranging from inland to coastal areas. The research findings showed that pore water in marine clay is largely dominated by bound water, and the bound water content changing with temperature in each soil layer can be studied in four stages.

 

According to my initial assessment, the article is well structured and has the potential to contribute to the literature. Therefore, I think that the article can be accepted after some revision. Some corrections given below may be applied before its acceptance:  

Response: Thank you very much for your recognition and affirmation of our work. Your comments are very helpful in improving the level of the manuscript. We also recognize the inadequacy of the paper and have made detailed changes based on your suggestions. We will answer your questions one-on-one.

 

Comment 1: It is unclear whether repeated measurements were made on the same samples in the manuscript, and information on the consistency and standard deviations of the results is not provided. The lack of repeatability data makes it difficult to assess the reliability of the findings. In addition, critical experimental parameters such as the initial water content and density of the samples were not explicitly controlled. This lack raises concerns about the repeatability and accuracy of the experimental results. The authors are advised to:

*Perform repeated measurements to ensure reliability and consistency of the results.

*Report standard deviations and variability in measurements.

*Clearly define the initial water content and density control to increase experimental repeatability.

Response: Thank you very much for your helpful suggestions. According to your suggestions. We have made revisions to the paper, and we apologize for any inconvenience this may have caused you in reading it! We ensured that all samples were measured three times repeatedly, the results were averaged, and the standard deviations were all less than 1. In addition, this paper quantifies the bound water content in the three types of marine clays during freezing, and the obtained T₂ values are not constant but rather several ranges. Therefore, this paper does not control for a single initial water content and density. However, there are ranges of initial water contents and densities for each type of marine clay in the study area. The specific revisions are as below:

Lines 180-182, page 5.

For all the tests in this paper, we ensured that all samples were measured three times repeatedly, the results were averaged, and the standard deviations were all less than 1.

Lines 143-148, page 4.

As shown in Table 2, the water content of mucky clay and clay layers in the study area is relatively high, with 40.81%-45.88% for silty clay, 39.22%-46.63% for clay, while the water content of silty clay is relatively low, ranging from 29.18%-37.93%. However, the density of silty clay is greater than that of mucky clay and clay, where the density of silty clay is 1.8-2.05 g/cm³, the density of silty clay is 1.75-1.83 g/cm³, and the density of clay is 1.78-1.83 g/cm³.

 

Comment 2: Microstructural analysis using SEM images is limited to qualitative observations and cannot provide a quantitative assessment. In particular, important parameters such as pore size distribution, specific surface area, and particle shape factors are not calculated. The lack of these quantitative measurements limits the verification of the relationship between microstructure and bound water content. Authors are encouraged to:

*Perform quantitative image analysis using advanced techniques (e.g. ImageJ or MATLAB) to calculate pore size distribution, specific surface area, and particle shape factors.

*Relate quantitative microstructural parameters to bound water content to support proposed mechanisms.

Response: Thank you very much for your attentive reviews and valuable suggestions. In particular, the suggestion to utilize SEM images for quantitative analysis of microstructure and relate the results to bound water content certainly provides a new perspective to deepen the study. However, in this study, we mainly focus on the application of NMR techniques for the quantitative analysis of the bound water content of marine clays, while the qualitative analysis by SEM aims to provide intuitive microstructural information, such as the relationships between the shape of the clay aggregates and the specific surface area, and thereby aids in the understanding of the behavior of bound water during the freezing process. Although quantitatively analyzing the relationship between microstructural parameters and bound water content is undoubtedly an attractive research area, we faced technical implementation challenges in this study, including accuracy limitations of SEM image analysis and complexity of data interpretation. In addition, considering the limitations of research resources and time, we decided to concentrate our resources on the in-depth application of NMR techniques. Nevertheless, we fully recognize the research value of this field and plan to explore more systematic quantitative analysis methods in subsequent studies.

 

Comment 3: The manuscript does not adequately compare its findings to the existing literature on bound water content and freeze-thaw cycles. In particular, recent work on thermodynamic phase change models and microstructure-water interactions is ignored. This weakens the contribution of the manuscript to the literature and raises questions about its claim to novelty. To strengthen the impact and relevance of the work, authors should:

*Include a comprehensive literature review that situates the work in the context of recent developments in thermodynamic modeling and microstructure-water interactions.

*Compare the results with findings from recent studies to highlight the contributions and limitations of the current work.

*Discuss the implications of the findings in the context of existing models and theories.

Response: We sincerely appreciate the valuable comments. Based on your suggestions, we have added some references about thermodynamic models in the article and findings compared with the results. In addition, we also added the limitations about the study in conclusions. The additions are listed below:

Lines 76-94, page 2.

Moreover, deriving the relationship between soil microstructure and pore water through thermodynamic models has become a hot issue in soil-water research recently. Xiao et al. proposed a thermodynamic model for predicting unfrozen water content, established an empirical equation between unfrozen water content and pore radius, and illustrated the phase change mechanism of frozen soil from a thermodynamic point of view. Yang et al. proposed a thermodynamic model based on solid mechanics that can be used to describe the mechanical characteristics and temperature effects of fine-grained gassy soils. Li et al. developed a thermodynamic model of freeze nucleation in saline soils to quantify the supercooling and freeze crystallization properties of saline soils in cold regions. In summary, the thermodynamic model can relate the microstructure to the soil-water interactions, reveal the mechanism of soil-water interactions during the freezing process, and then quantitatively predict the amount of unfrozen water in the soil. However, the selection and determination of parameters in thermodynamic models is often a complex and difficult process. Due to the complexity and diversity of soils, the thermodynamic parameters of different soils may differ significantly. Therefore, in this paper, the NMR test is selected and combined with SEM images to quantitatively analyze the bound water content in marine clay and qualitatively analyze the effect of microstructure, so that it can reveal the change behavior of bound water during the freezing process of marine clay in a more comprehensive perspective.

Line 293, page 8.

Therefore, this water film can be referred to as both the counterion layer and the bound water layer. Based on this charged capacity of the clay particles, the number of clay particles will significantly influence the content of bound water, which is confirmed by Zhang et al. .

Lines 316-317, page 9.

The above conclusion is in agreement with that of Mitchell based on the Gouy-Chapman double layer theory.

Lines 358-360, page 11.

Meanwhile, Han et al. considered that bound water film is also related to the specific surface area of the clay particles, the larger the specific surface area, the greater the area of the water film around the clay particles.

Lines 528-534, page 16.

However, there are some limitations in this paper. In this study, the NMR method was used to quantitatively analyze the bound water content of marine clay and qualitatively analyze the microstructure of marine clay in conjunction with SEM images. In future research, more emphasis will be placed on quantitatively analyzing SEM images, extracting microstructural parameters, and applying the microstructural parameters to the thermodynamic model to reveal the relationships between the microstructural parameters and soil-water interaction.

 

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

Please find my comments in the attached pdf file.

Cheers,

A

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

Thank you for your kind reviews of our manuscript entitled “Quantitative analysis of bound water content in marine clay and its influencing factors during the freezing process by nuclear magnetic resonance”. Special thanks to your good comments and suggestions, and we are deeply impressed by your conscientious, rigorous, high–efficiency and responsible attitude towards the evaluation work. These comments are all valuable and very helpful for revising and improving our paper.

Under the guidance your comments, we have carefully and extensively revised and polished our manuscript. Revisions in the paper have been marked in red. We hope that the corrections will meet with approval and look forward to hearing from you for any further consideration. A point to–point response is provided below.

 

Comment 1: Make this a separate sentence for clarity. Previous sentence is too long and the somehow link of previous sentence with this one appears weak.

“allowing marine soft clay soil foundations to be widely used in engineering (Feng et al., 2021; Li et al., 2022).  “

Response: Thank you very much for your suggestion. We have broken this long sentence into shorter ones according to your suggestion. The revisions are as below:

Lines 26-28, page 1.

Recently, with the rapidly growing economy and construction, world land resources are in shortage, and reclamation projects have become a new means of urbanization. Therefore, marine soft clay soil foundations are widely used in engineering.

 

Comment 2: Could you please provide a bit of context of why marine clay is important from engineering perspective and the list challenges associated with marine clay.  In present form marine clay is appearing out of the blue and making it difficult for the reader to understand the context. 

“However, the ensuing engineering geological problems have gradually emerged.”

Response: Thank you very much for your professional suggestions. We apologize for the inconvenience that may caused you. In fact, in the next sentence of the text, the engineering properties of marine clays and the engineering problems they raise, are noted. Additionally, for the reader's better understanding, we have added a summary sentence. The specific location is as below:

Lines 28-38, page 1.

Yet, the ensuing engineering and geological problems have gradually emerged. Marine clay, characterized by a high content of clay particles, elevated water content, and numerous pores, exhibits significant compressibility and low bearing capacity. These properties contribute to pronounced creep behavior in clay, resulting in settlement deformations that can lead to severe safety incidents. Pores of clay contain large amounts of bound water, which enables the soil to have complex physical and mechanical properties. Furthermore, variations in both the composition and quantity of bound water influence the hydration behavior of clay particles, resulting in different properties of soil. As mentioned above, marine clay raises many geological problems due to its properties and brings many challenges to marine clay engineering. 

 

Comment 3: insert space

 “and strength(Ye et al., 2016; Zhu et al., 2007).”

Response: Thank you very much for your helpful suggestion. We have inserted space according to your suggestion. The revision is as below:

Lines 49-50, page 2.

and strength ^{20, 21}.

 

Comment 4: This figure should be in the centre of the page rather than side. Just a suggestion.

 

Response: Thank you very much for your kind suggestion. The entire article was typeset with the help of an assistant editor, so we'd like to keep this image in place for the time being, and once again, thank you sincerely for your valuable advice!

 

Comment 5: Not only clay content but clay type is also very important aspect for the stability of infrastructure. For example smectites are prone to clay absorption and interlayer expansion which may lead to instability and even failure of the structures.

If you can provide brief perspective on clay types it could be useful.

Response: We sincerely appreciate the valuable comments. Based on your suggestions, we have added descriptions of clay types. The additions are listed below:

Lines 455-467, page14.

In addition, the type of clay directly affects the clay-water interaction. Because the type of clay determines its mineral composition, particle shape, specific surface area and other physicochemical properties, such as cation exchange capacity. Different types of clay have different water absorption and water holding capacities. For example, kaolinite, montmorillonite and illite are three common clay minerals with different water adsorption capacities. Montmorillonite has a layered structure, and it is easy to absorb water and swell between layers, so its bound water content is high, and it has a large volume change after absorbing water, which generates a large pressure on the surrounding soil. Kaolin, on the other hand, is relatively more stable and less water-absorbing and swelling. In summary, the type of clay has a significant impact on the stability of infrastructure by affecting the ability of the soil to adsorb water and its physicochemical properties. Therefore, the influence of clay type needs also to be fully considered during infrastructure construction and maintenance.

 

Comment 6:  Textures are not fully visible in these images. I suggest you enlarge this photo to the entire page as I can't clearly see any details.

Response: We are sorry for the inconvenience we made in the article, we have enlarged this figure to the entire page. The specific location is in page 10, figure 7.

 

Comment 7: Move this text to a new paragraph.

 

Response: We sincerely appreciate the helpful suggestion. Based on your suggestion, we have made the revisions. The revisions are as below:

Page 12.

 

 

Comment 8: perfect spot to bring in the clay type context provided in previous comments here.

 

Response: We sincerely appreciate detailed suggestion. Based on your suggestion, we have made the revisions. The revisions are as below:

Lines 455-467, page14.

In addition, the type of clay directly affects the clay-water interaction. Because the type of clay determines its mineral composition, particle shape, specific surface area and other physicochemical properties, such as cation exchange capacity. Different types of clay have different water absorption and water holding capacities. For example, kaolinite, montmorillonite and illite are three common clay minerals with different water adsorption capacities. Montmorillonite has a layered structure, and it is easy to absorb water and swell between layers, so its bound water content is high, and it has a large volume change after absorbing water, which generates a large pressure on the surrounding soil. Kaolin, on the other hand, is relatively more stable and less water-absorbing and swelling. In summary, the type of clay has a significant impact on the stability of infrastructure by affecting the ability of the soil to adsorb water and its physicochemical properties. Therefore, the influence of clay type needs also to be fully considered during infrastructure construction and maintenance.

 

Comment 9: As said earlier not only clay content but clay type is also significant.

 

Response: We sincerely appreciate helpful suggestion. Based on your suggestion, we have made the revisions. The revisions are as below:

Line 510, page 15.

The clay content and clay types

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have improved their manuscript compared to the previous version. The lack of subject matter, scope and connection with the literature has been eliminated and I think it is acceptable as it is.