Evaluation of Performance of Polyacrylamide-Modified Compacted Clay as a Gas Barrier: Water Retention and Gas Permeability and Diffusion Characteristics
Round 1
Reviewer 1 Report
The paper discusses the gas permeability and the gas diffusion through a barrier of compacted clay modified by the polyacrylamide (PAM). The scope is well related to the sustainable environmental geotechnics and it is of interest to the geotechnical community.
In my opinion the manuscript is interesting and quite well explained. The work has a laboratory nature, the test procedure is logical, although, Dear Authors, it requires some explanations (additional description in the study) before it can be accepted for publication. Also the style of the text and References must be formatted according to publishing guidelines. Particular attention is needed at the following:
GENERAL COMMENTS:
- ALL MANUSCRIPT - The text editing is negligent. You should read “Instructions for Authors”.
- REFERENCES: Please format the References according to publishing guidelines. Inter alia, the References should be quoted by numbers in square brackets [] in order of appearance, and not alphabetically.
SPECIFIC COMMENTS:
- Page 1, lines 21, 25 (Abstract):
Please explain the abbreviations: PAM, LLd, Z-PAM. All abbreviations/symbols used in Abstract and also for the first time in the main text should be preceded by the full name. - Page 1 (line 34) and all subsequent text:
Inappropriate reference to literature. You should write only References number in the all text. If you need to write a researcher name, then give only the name and References number, but without the year, for example:
- “(…) migration upwards (Mahmoodlu et al., 2015).”: it should be “(…) migration upwards [X].”;
- “Rouf et al., (2016) demonstrated that (…)”: it should be “Rouf et al. [X] demonstrated that (…)”. - Page 3, lines 130-131:
“The compacted clay samples were prepared by adopting the hydraulic sample preparation method and (…)” - Please briefly describe the method used. - Page 4, line 132:
“ASTM D4318 (ASTM, 2010)” - 2010 or 2016? In the text it is "2010", while in the References "2016". - Page 4, line 135:
“The compacted clay samples were (…)” - What was the method of compacting the clay samples? What was the size of the samples for the permeability tests? - Page 4, line 135:
Please explain the symbols: wopt and ρdmax. - Page 4, Table 2:
- Please systematize the Table, e.g. you should complete the missing units for tests parameters;
- “1200w”: What is this “w”?
- “water loss rate Ws”: Shouldn't it be “shrinkage limit ws”? - All Equations:
Please format the Equations according to publishing guidelines. - Page 5, line 179:
“The size was set to 61.8×20 mm.” – The sample sizes written incorrectly. The description does not show the actual shape of the sample. You should specify diameter or width, height etc. - Section 1.3.4. Liquid limit test:
By what method was the liquid limit determined: the Casagrande method or the cone penetrometer test? Each of these methods generally produces different results. - Figure 2:
Incorrect Figure description. You should write the main title at first (a short explanatory title), then the description of the subsections (a) …; (b) …. etc. (see your well-described Figure 11). - Figures 5 and 7:
You should standardize the notation and consistently give in the drawing either only the name of the parameter or the name of the parameter with its symbol. For example: “Water Content w; Air Permeability KP” or “Water Content; Air Permeability”. - Figure 6:
Please check the correctness of the references in the drawing and in the References:
- Vangpaisal et al. (2002) or Vangpaisal (2002),
- Pitanga et al. (2010) or Pitanga et al. (2011). - Figure 6:
- “GCL-Vangpaisal et al. (2002，GCL)”: Why was “GCL” written twice?
- “GCL-Pitanga et al. (2010，GCL)”: Why was “GCL” written twice? - Figure 8:
It should be: “Bouazza and Rahman (2007)” - Figures 9, 10 and 11:
Please explain the abbreviation “CK”. - Conclusions:
- In Conclusions, all abbreviations and symbols should be explained again (they should be preceded by the full name).
- You should more clearly indicate your own contribution to the presented issue. - List of symbols:
It is good practice to include a list of symbols. I appreciate it. However, please complete the list with all the symbols used in the manuscript.
Good luck!
Author Response
Response to reviews of the paper entitled:
Investigate the permeability and diffusion coefficient of the gas barrier with polyacrylamide (PAM) modified compacted clay
Manuscript Number: applsci-1731307 (Research Article)
Dear Editor,
The authors would like to thank the reviewers and the Editor for their rigorous and methodical review. The comments have helped to improve our revised manuscript. All of the review comments are incorporated into the revised manuscript. To enhance the readability and impact of the paper, a professional English editor has been invited by authors to revise this manuscript. Itemized responses to the reviewers’ comments and suggestions are provided below.
Response to Reviewer #1:
Above all, we would like to thank you for the specific and constructive comments on this manuscript. It has helped shape the work in all aspects and allowed us a useful examination of our work and the improvements that have been made.
Below are specific responses to the comments and criticisms.
Reviewer #1: ALL MANUSCRIPT - The text editing is negligent. You should read “Instructions for Authors”.
Response: It has been modified by authors.
Reviewer #1: REFERENCES: Please format the References according to publishing guidelines. Inter alia, the References should be quoted by numbers in square brackets [] in order of appearance, and not alphabetically.
Response: All the references have been modified in manuscript.
Reviewer #1: Page 1, lines 21, 25 (Abstract):
Please explain the abbreviations: PAM, LLd, Z-PAM. All abbreviations/symbols used in Abstract and also for the first time in the main text should be preceded by the full name.
Response: The abbreviations has been explained in abstract: PAM (Polyacrylamide), LLd (the dimensionless results of LL), Z-PAM (Zwitterionic Polyacrylamide).
Reviewer #1: Page 1 (line 34) and all subsequent text:
Inappropriate reference to literature. You should write only References number in the all text. If you need to write a researcher name, then give only the name and References number, but without the year, for example:
- “(…) migration upwards (Mahmoodlu et al., 2015).”: it should be “(…) migration upwards [X].”;
- “Rouf et al., (2016) demonstrated that (…)”: it should be “Rouf et al. [X] demonstrated that (…)”.
Response: The references cited in manuscript have been modified.
Reviewer #1: Page 3, lines 130-131:
“The compacted clay samples were prepared by adopting the hydraulic sample preparation method and (…)” - Please briefly describe the method used.
Response: The compacted clay samples were prepared following the requirement of ASTM D4318 [31] and ASTM D2216-19 [32], respectively. The sample preparation process was shown in figure 1. Firstly, the dried clay was mixed with an appropriate amount of polyacrylamide and blended evenly after adding water. Then the mixed soil put in the sample preparation device (this device uses hydraulically power). Finally, the compacted clay sample was made.
Reviewer #1: Page 4, line 132:
“ASTM D4318 (ASTM, 2010)” - 2010 or 2016? In the text it is "2010", while in the References "2016".
Response: The references have been modified in manuscript.
Reviewer #1: Page 4, line 135:
“The compacted clay samples were (…)” - What was the method of compacting the clay samples? What was the size of the samples for the permeability tests?
Response: This explanation has been added in manuscript: The soil can reach the maximum degree of compaction only when it satisfies the wopt and ρdmax. This is because that Ralph R. Proctor proposed a compaction test where a soil sample is compacted by means of a set of blows of a hammer per lift, which prove that the maximum dry density (ρdmax) of a soil is related to certain moisture, called as optimum moisture content (wopt) [36]. The size of the soil samples was set to 61.8×20 mm cylinder.
Reviewer #1: Page 4, line 135:
Please explain the symbols: wopt and ρdmax.
Response: This explanation has been added in manuscript: This is because that Ralph R. Proctor proposed a compaction test where a soil sample is compacted by means of a set of blows of a hammer per lift, which prove that the maximum dry density (ρdmax) of a soil is related to certain moisture, called as optimum moisture content (wopt) [36].
Reviewer #1: Page 4, Table 2:
- Please systematize the Table, e.g. you should complete the missing units for tests parameters;
- “1200w”: What is this “w”?
- “water loss rate Ws”: Shouldn't it be “shrinkage limit ws”?
Response: (1) The table has been modified. (2) “1200w” has been modified as 12 million. (3) water loss rate is defined by authors. The calculated formula has been listed in manuscript.
Reviewer #1: All Equations:
Please format the Equations according to publishing guidelines.
Response: The format has been modified in manuscript.
Reviewer #1: Page 5, line 179:
“The size was set to 61.8×20 mm.” – The sample sizes written incorrectly. The description does not show the actual shape of the sample. You should specify diameter or width, height etc.
Response: It has been modified in manuscript: The height and diameter of soil sample are 20 mm and 61.8 mm, respectively.
Reviewer #1: Section 1.3.4. Liquid limit test:
By what method was the liquid limit determined: the Casagrande method or the cone penetrometer test? Each of these methods generally produces different results.
Response: The test method has been listed as follows: we dried all of the required soil samples in an oven and took a part of the dried soil to measure the liquid limit and plastic limit. Liquid limit and plastic limit are gotten by liquid-plastic combine tester according to Boundary water content test method SL237-007-1999 [53].
Reviewer #1: Figure 2:
Incorrect Figure description. You should write the main title at first (a short explanatory title), then the description of the subsections (a) …; (b) …. etc. (see your well-described Figure 11).
Response: The title has been modified as follows: Liquid limit of CCC mixed with Z-PAM. (a) Influence of PAM amount on the LL of the compacted clay, (b) Influence of different materials mixed with clay on LL/LLck of the compacted clay
Reviewer #1: Figures 5 and 7:
You should standardize the notation and consistently give in the drawing either only the name of the parameter or the name of the parameter with its symbol. For example: “Water Content w; Air Permeability KP” or “Water Content; Air Permeability”.
Response: It has been modified in manuscript.
Reviewer #1: Figure 6:
Please check the correctness of the references in the drawing and in the References:
- Vangpaisal et al. (2002) or Vangpaisal (2002),
- Pitanga et al. (2010) or Pitanga et al. (2011).
Response: All the references have been modified in manuscript.
Reviewer #1: Figure 6:
- “GCL-Vangpaisal et al. (2002，GCL)”: Why was “GCL” written twice?
- “GCL-Pitanga et al. (2010，GCL)”: Why was “GCL” written twice?
Response: It has been deleted in the figure.
Reviewer #1: Figure 8:
It should be: “Bouazza and Rahman (2007)”
Response: It has been modified in manuscript.
Reviewer #1: Figures 9, 10 and 11:
Please explain the abbreviation “CK”.
Response: CK means control blank. The explanation has been added in symbols List.
Reviewer #1: Conclusions:
- In Conclusions, all abbreviations and symbols should be explained again (they should be preceded by the full name).
- You should more clearly indicate your own contribution to the presented issue.
Response: 1) The abbreviations in conclusions have been explained again in manuscript. 2) Our own contribution has been listed in manuscript.
Reviewer #1: List of symbols:
It is good practice to include a list of symbols. I appreciate it. However, please complete the list with all the symbols used in the manuscript.
Response: The list has been added in manuscript.
Reviewer 2 Report
The document requires standardization, language improvement and editorial corrections. Suggestions are listed below. After changes, it can be accepted for printing.
-There is a need for linguistic correction and checking typos of the abstract and the article e.g. please change "contaminated site of ..." to contaminated site in Changzhou"; "performance. ." to "performance." (double dots are present throughout the text); "the Kp of reduced " to "the Kp reduced"; "soil.." to "soil.", "contaminated sites for effectively preventing " to "contaminated sites to effectively prevent", please check the full text;
-I suggest that supplementary materials (Figure 1) should be included in the article, need not be the entire drawing, but showing that there are no cracks for the selected PAM;
-in Table 1, please explain the abbreviation "COV";
-units in Table 1 are not in parentheses, and units in Table 2 are in parentheses - please standardize;
-[137] "the dry density was set as 1.78 g/cm" - check unit;
-please change "baked" [139] on "dried",
-check eq. 1 and 2 - "23%?";
-[156] what was compaction pressure?;
-In Figure 2, 6 and 8, the literature data cannot be compared because the tests were performed on other clays. They should be described in the text;
-Figure 5's caption is split on another page;
-data analysis should be more critical;
-please standarize References (and change title from "Reference" to "References").
Author Response
Response to reviews of the paper entitled:
Investigate the permeability and diffusion coefficient of the gas barrier with polyacrylamide (PAM) modified compacted clay
Manuscript Number: applsci-1731307 (Research Article)
Response to Reviewer #2:
Above all, we would like to thank you for the specific and constructive comments on this manuscript. These have helped us reexamine our manuscript critically and make the improvements. The point to point responds to the reviewer’s comments are listed as following.
Reviewer #2: -There is a need for linguistic correction and checking typos of the abstract and the article e.g. please change "contaminated site of ..." to contaminated site in Changzhou"; "performance. ." to "performance." (double dots are present throughout the text); "the Kp of reduced " to "the Kp reduced"; "soil.." to "soil.", "contaminated sites for effectively preventing " to "contaminated sites to effectively prevent", please check the full text;
Response: The linguistic correction has been made by authors.
Reviewer #2: -I suggest that supplementary materials (Figure 1) should be included in the article, need not be the entire drawing, but showing that there are no cracks for the selected PAM;
Response: The figure has been added in manuscript.
Reviewer #2: -in Table 1, please explain the abbreviation "COV";
Response: COV is the abbreviation of Covariance (It is a measure of the joint variability of two random variables)
Reviewer #2: -units in Table 1 are not in parentheses, and units in Table 2 are in parentheses - please standardize;
Response: The table has been modified in manuscript.
Reviewer #2: -[137] "the dry density was set as 1.78 g/cm" - check unit;
Response: The unit has been modified in manuscript.
Reviewer #2: -please change "baked" [139] on "dried",
Response: It has been modified in manuscript.
Reviewer #2: -check eq. 1 and 2 - "23%?";
Response: It has been modified and it is 25% in equation.
Reviewer #2: -[156] what was compaction pressure?;
Response: The introduction of compaction pressure of device has been added in manuscript: The compaction pressure ranges from 10 KN to 100 KN.
Reviewer #2: -In Figure 2, 6 and 8, the literature data cannot be compared because the tests were performed on other clays. They should be described in the text;
Response: 1) The comparison has been made use the dimensionless results in Figure 2; 2) The figure 6 and figure 8 mainly compare the gas permeability and gas diffusion coefficient, some authors also use this method to explain the barrier performance.
Reviewer #2: -Figure 5's caption is split on another page;
Response: It has been modified in manuscript.
Reviewer #2: -data analysis should be more critical;
Response: It has reanalysis in manuscript.
Reviewer #2: -please standarize References (and change title from "Reference" to "References").
Response: It has been modified in manuscript.
Author Response File: 
Author Response.docx
Reviewer 3 Report
The manuscript was interesting and relevant with the scope of the journal. However, it would need following changes/modifications prior to be reconsidered for any next step:
1. A glossary of the term was available. It should add more words such as CCC, CCL, VOC, GCL etc.
2. Line 21, please add full name of PAM.
3. Line 26, remove one extra full stop.
4. What was the difference between CCC and CCL? Please add separately as a footnote.
5. Line 47, consider revising the term ‘VOC gas’.
6. Line 49, “ As geosynthetic clay liner (GCL) has relative research…” clarify the text with better sentencing.
7. All the references, should be in MDPI style.
8. Line 60-62, please consider revising the grammar.
9. Line 65, “similar phenomena (Ref,).”? What was the meaning of “ref” here?
10. Line 68-71, The past and present tenses were not consistent? Please ensure the consistency of the tenses throughout the manuscript.
11. Line 76, “which often used as” sentence, revise the grammar. Similarly lines 89-93 and 95-97.
12. Numbering of the section was wrong. Introduction should be 1. Also revise “Raw material section” to “Materials and Methods” section. Delete the word “Raw”.
13. Materials section did not have complete information of the “clay” samples. It was not clear why the chosen soil sample as referred as clay. Also, differences in particles in the soil (called clay here) size and mineralogy of the sample was not mentioned. Studies such as EPMA (Electron Probe Micro Analyzer) and SEM (Scanning electron microscope) analyses would be helpful.
14. For the procedures described in materials and method section (ASTM D6907-05 (ATSM 2016) and ASTM108D6044-21 (ATSM 2021)., the results of each sample should be included in the paper/ or atleast as SI (supplementary information).
15. Line 129, WRC Test,” The dried clay was mixed with an appropriate amount of polyacrylamide and
blended evenly after adding water”. What was an “APPROPRIATE AMOUNT”? Please clarify each step here.
16. Table 2, Please add explanation of important terms or the meaning of units as foot notes or caption e.g., Type: Zwitterionic (give its unit formula)?, What was the meaning of weight = 1200w. What did w mean here? Add this in footnote/caption. Why the table color was darker?
17. Line 150-152, and 177-179 Consider revising this sentence (grammar).
18. Line 154-156, Give exact amount and ratio of PAM.
19. Line 183, “The third step was to open the air” which THIRD step? What were the first and second steps here?
20. Line 182, “petroleum jelly was evenly” please add why was it applied?
21. A rather major concern here, The paper was very confusing to read. It lacked clarity. The experimental, results and discussion sections were merged together, specially the results were also mixed up with previous references and information that was not directly related to the present results. The data obtained by other groups should be removed from results section and move to introduction or discussion section e.g., Soil water characteristic curve (SWCC) test section should only have the current research work/experiments/results, the other information should be moved to either introduction or discussion section. Are methods, results and discussions merged together? Please separate them.
-Same issue for “2.1. Liquid limit” section, 2.2 WRC section, Gas permeability section, 2.3. Gas diffusion coefficient
22. Line 278, What is the meaning of xx to xx?
23. Throughout the text there are consistencies of tenses either past or present. Please ensure that the tenses are consistent.
24. Line 439, PAM Modification. How was this done?
25. Line 443, Soil Gas. Its not clear soil or clay? Why the term “clay” was used before and here soil?
26. The paper should be clearly divided into introduction, experimental, results/discussion/ conclusions. Results should only have the authors own research work rather than the previous literature, all the relevant information should either go to introduction or discussion.
27. Figure 1. 3D printing gas diffusion chamber should have complete instrumentation details. Please give all the details of this chamber. If appropriate with references, if it was constructed in home then how?
28 Once again, please separate, experimental, results, discussion, and conclusions section. This manuscript lacked clarity.
29. In conclusions sections please add some practical implications and significance of your findings.
Author Response
Response to reviews of the paper entitled:
Investigate the permeability and diffusion coefficient of the gas barrier with polyacrylamide (PAM) modified compacted clay
Manuscript Number: applsci-1731307 (Research Article)
Response to Reviewer #3:
We would like to thank Reviewer #3 for patience and diligence in reviewing this manuscript. The comments are essential and have helped us improve the manuscript drastically. Please find below responses to specific comments and criticisms raised.
Reviewer #3: A glossary of the term was available. It should add more words such as CCC, CCL, VOC, GCL etc.
Response: It has been added in list of symbols
Reviewer #3: Line 21, please add full name of PAM.
Response: It has been added in abstract: PAM (Polyacrylamide).
Reviewer #3: Line 26, remove one extra full stop.
Response: It has been modified in manuscript.
Reviewer #3: What was the difference between CCC and CCL? Please add separately as a footnote.
Response: CCC is compacted clay cover, CCL is compacted clay liner. Authors make a slip in writing. All the CCL has been modified as CCC.
Reviewer #3: Line 47, consider revising the term ‘VOC gas’.
Response: It has been revised as ‘VOCs’.
Reviewer #3: Line 49, “ As geosynthetic clay liner (GCL) has relative research…” clarify the text with better sentencing.
Response: It has been revised as follows: In recent years, geosynthetic clay liner (GCL) is usually used as the VOC barrier in contaminated sites, which is considered better than the CCC.
We also add some explanation about why we chose the CCC as the study object: However, the bentonite in China GCL is usually calcium bentonite. It is because China lacks sodium bentonite resources. The GCL filling with sodium bentonite usually has better barrier performance than calcium bentonite.
Reviewer #3: All the references, should be in MDPI style.
Response: It has been revised in the manuscript.
Reviewer #3: Line 60-62, please consider revising the grammar.
Response: It has been revised as follows: Nonetheless, the advection and diffusion are all playing a leading role when GCL has a low moisture content. Furthermore, the GCL will be cracking when moisture content reduces. The cracks will form the preferential path that VOCs will migrate through it. However, the bentonite in China GCL is usually calcium bentonite. It is because China lacks sodium bentonite resources. The GCL filling with sodium bentonite usually has better barrier performance than calcium bentonite.
Reviewer #3: Line 65, “similar phenomena (Ref,).”? What was the meaning of “ref” here?
Response: It is an error. It has been deleted.
Reviewer #3: Line 68-71, The past and present tenses were not consistent? Please ensure the consistency of the tenses throughout the manuscript.
Response: The sentence has been rewritten as follows: When the moisture content of the compacted clay is low, fissures are formed due to water loss [20]. The fissures will further develop into a crack network and eventually become the dominant path. VOCs migrate along cracks, posing a significant threat to the surrounding environment. Through laboratory tests, Drumm et al. [21] found that the permeability coefficient near soil cracks increased sharply, thus confirming the existence of dominant flow paths after soil cracks.
Reviewer #3: Line 76, “which often used as” sentence, revise the grammar. Similarly lines 89-93 and 95-97.
Response: It has been modified as follows:
- Polyacrylamide (PAM) is one of the most common super hydrogels (SAP) in industrial production [22]. It is often used as a water retention agent in agriculture with the excellent property of retaining water long-term [23].
- Therefore, the use of PAM to modify the CCC can improve the WRC of clay and enhance its gas barrier performance. In general, previous studies mainly focused on the mechanical and hydraulic properties of polymer-modified clay. However, the barrier performance of modified clay is still limited.
- In this study, the main purpose was to compare/investigate the gas barrier performance of PAM modified clay. A series of tests related to WRC and gas barrier performance, including the liquid limits, gas permeability, and gas diffusion. Furthermore, the optimal dosage of PAM was also evaluated. Through this study, it is hoped that it can contribute to a better understanding of CCC’s design and application in geo-environment engineering.
Reviewer #3: Numbering of the section was wrong. Introduction should be 1. Also revise “Raw material section” to “Materials and Methods” section. Delete the word “Raw”.
Response: It has been revised in the manuscript.
Reviewer #3: Materials section did not have complete information of the “clay” samples. It was not clear why the chosen soil sample as referred as clay. Also, differences in particles in the soil (called clay here) size and mineralogy of the sample was not mentioned. Studies such as EPMA (Electron Probe Micro Analyzer) and SEM (Scanning electron microscope) analyses would be helpful.
Response: The classification method has been added in the manuscript:
The plasticity chart has been made based on two standards (GB/T 50145–2007 and ASTM 2487) [55-56]. Figure 1 is the plasticity chart that can make soil classification. The soil of the contaminated site in Changzhou can be classified as clay with low LL based on table 2.
Reviewer #3: For the procedures described in materials and method section (ASTM D6907-05 (ATSM 2016) and ASTM108D6044-21 (ATSM 2021)., the results of each sample should be included in the paper/ or atleast as SI (supplementary information).
Response: It has been added in the supplementary information.
Reviewer #3: Line 129, WRC Test,” The dried clay was mixed with an appropriate amount of polyacrylamide and blended evenly after adding water”. What was an “APPROPRIATE AMOUNT”? Please clarify each step here.
Response: It has been revised as: …with different amounts (see in table 2) of polyacrylamide…
Reviewer #3: Table 2, Please add explanation of important terms or the meaning of units as foot notes or caption e.g., Type: Zwitterionic (give its unit formula)?, What was the meaning of weight = 1200w. What did w mean here? Add this in footnote/caption. Why the table color was darker?
Response: It has been revised in the manuscript.
Reviewer #3: Line 150-152, and 177-179 Consider revising this sentence (grammar).
Response: It has been modified in the manuscript.
Reviewer #3: Line 154-156, Give exact amount and ratio of PAM.
Response: We compared different mount of PAM mixture soil. So we revised this sentence as: …with different amounts of PAM…
Reviewer #3: Line 183, “The third step was to open the air” which THIRD step? What were the first and second steps here?
Response: It has been revised as: Finally, open the air inlet and outlet valves, open the nitrogen bottle, and adjust the flow control valve to make nitrogen enter the diffusion chamber evenly and steadily through the inlet.
Reviewer #3: Line 182, “petroleum jelly was evenly” please add why was it applied?
Response: It has been added in manuscript.
Reviewer #3: A rather major concern here, The paper was very confusing to read. It lacked clarity. The experimental, results and discussion sections were merged together, specially the results were also mixed up with previous references and information that was not directly related to the present results. The data obtained by other groups should be removed from results section and move to introduction or discussion section e.g., Soil water characteristic curve (SWCC) test section should only have the current research work/experiments/results, the other information should be moved to either introduction or discussion section. Are methods, results and discussions merged together? Please separate them.
Response: The results and discussion are hard to separate. Because our results need to compare with previous studies. List the results without other researchers’ comparing can’t explain our works clearly.
Reviewer #3: -Same issue for “2.1. Liquid limit” section, 2.2 WRC section, Gas permeability section, 2.3. Gas diffusion coefficient
Response: It has been modified in the manuscript.
Reviewer #3: Line 278, What is the meaning of xx to xx?
Response: It has been revised as follows: …as the PAM amount ranged from 0.2% to 1.0%.
Reviewer #3: Throughout the text there are consistencies of tenses either past or present. Please ensure that the tenses are consistent.
Response: It has been revised in the manuscript.
Reviewer #3: Line 439, PAM Modification. How was this done?
Response: It has been revised as follows: The WRC of compacted clay significantly improves after adding PAM…
Reviewer #3: Line 443, Soil Gas. Its not clear soil or clay? Why the term “clay” was used before and here soil?
Response: It has been revised as Clay in the manuscript.
Reviewer #3: The paper should be clearly divided into introduction, experimental, results/discussion/ conclusions. Results should only have the authors own research work rather than the previous literature, all the relevant information should either go to introduction or discussion.
Response: The results and discussion are hard to separate. Because our results need to compare with previous studies. List the results without other researchers’ comparing can’t explain our works clearly.
Reviewer #3: Figure 1. 3D printing gas diffusion chamber should have complete instrumentation details. Please give all the details of this chamber. If appropriate with references, if it was constructed in home then how?
Response: Complete instrumentation figure has been added to the manuscript. The actual photo has been added in SI.
Reviewer #3: 28 Once again, please separate, experimental, results, discussion, and conclusions section. This manuscript lacked clarity.
Response: The results and discussion are hard to separate. Other parts are separate.
Reviewer #3: 29. In conclusions sections please add some practical implications and significance of your findings.
Response: We have conducted a lot of practical engineering and some situ experiments. But in this paper, we only discuss the experiment parts.
Author Response File: Author Response.docx
Reviewer 4 Report
Acceptable in its current form.
Author Response
Thank your for your recognition. We also make some revisions in the manuscript.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear Authors,
I thank you for taking account of all my comments and suggestions. I appreciate your efforts to make your study more attractive for the Reader. No further comments. I recommend to publish this manuscript.
Author Response
Thank you for your recommendation.
Reviewer 3 Report
Most of the issues have been resolved by the authors. Just a few minor comments:
1. The following paragraph still has some minor errors. Please revise this,
“In this study, the main purpose was to compare/investigate the gas barrier performance of PAM modified clay. A series of tests related to WRC and gas barrier performance, including the liquid limits, gas permeability, and gas diffusion. Furthermore, the optimal dosage of PAM was also evaluated. Through this study, it is hoped that it can contribute to a better understanding of CCC’s design and application in geo-environment engineering”.
The first sentence should be revised to, “ the main purpose of the study was to investigate…..”
The sentence, “A series of tests related to WRC and gas barrier performance, including the liquid limits, gas permeability, and gas diffusion.” Still needs revision. It seems incomplete.
2. The Materials and methods section heading should be "Materials and Methods".
3. Figure 2 seemed a bit out of place.
4. Does Section 3, the "test results" section actually mean the "Results & Discussions" section? If so please use the latter term.
5. I still recommend seeking the help of an English-speaking colleague to improve the grammar of the paper.
Author Response
Response to reviews of the paper entitled:
Investigate the permeability and diffusion coefficient of the gas barrier with polyacrylamide (PAM) modified compacted clay
Manuscript Number: applsci-1731307 (Research Article)
Response to Reviewer #3:
Above all, we would like to thank you for the specific and constructive comments on this manuscript. These have helped us reexamine our manuscript critically and make the improvements. The point to point responds to the reviewer’s comments are listed as following.
Reviewer #3: The following paragraph still has some minor errors. Please revise this,
“In this study, the main purpose was to compare/investigate the gas barrier performance of PAM modified clay. A series of tests related to WRC and gas barrier performance, including the liquid limits, gas permeability, and gas diffusion. Furthermore, the optimal dosage of PAM was also evaluated. Through this study, it is hoped that it can contribute to a better understanding of CCC’s design and application in geo-environment engineering”.
The first sentence should be revised to, “ the main purpose of the study was to investigate…..”
The sentence, “A series of tests related to WRC and gas barrier performance, including the liquid limits, gas permeability, and gas diffusion.” Still needs revision. It seems incomplete.
Response: It has been revised in manuscript:
The main purpose of this study was to compare/investigate the gas barrier performance of PAM modified clay. A series of tests related to WRC and gas barrier performance, including the liquid limits, gas permeability, and gas diffusion were conducted.
Reviewer #3: The Materials and methods section heading should be "Materials and Methods".
Response: It has been revised as follows: Materials & Methods
Reviewer #3: Figure 2 seemed a bit out of place.
Response: The name of figure 2 has been revised as follows: Clay cracking with various content and type of PAMs.
Reviewer #3: Does Section 3, the "test results" section actually mean the "Results & Discussions" section? If so please use the latter term.
Response: It has been revised as follows: Results & Discussion
Reviewer #3: I still recommend seeking the help of an English-speaking colleague to improve the grammar of the paper.
Response: It has been improved by my colleague. Thanks for your advice.
Author Response File: Author Response.docx
