Advancements in Soft Soil Stabilization by Employing Novel Materials through Response Surface Methodology
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe study is of interest and the structure of the manuscript is appropriate. However, the discussion of the results obtained in the study is generally insufficient. There is no comparison in the discussion section with the results of previous studies.
Lines 41-44: The statement contained in this judgment is not entirely true in the terms stated: it is not certain that Portland cement decreases strength and generates high plastic shrinkage.
Line 79: From this line it would be advisable to consider a new paragraph because it deals with another point about BA
Line 108: OPC: Acronyms/Abbreviations/Initialisms should be defined the first time they appear
Lines 101-103: What type of treatments are indicated and whether they have been carried out on the materials used in this study.
Table 1: Missing units of the Specific Gravity
Line 116: It is indicated that BA has a low pozzolanic reaction. However, the article should reflect some data or analysis to corroborate this statement, which would allow a better understanding of how it works in soil stabilization.
Line 156: The concentration of the different oxides present in BA should be known in order to be able to define their pozzolanic activity. An additional XRF analysis could be of interest.
Line 178: From a civil engineering point of view, a maximum curing period of 14 days would be insufficient to know the behavior of a material with pozzolanic characteristics. It would be desirable to know the behavior at least at 28 days of curing time.
It would be appropriate to discuss the results in the context of other research, not only to present the results obtained. In the discussion section, no comparison is made with the results of previous studies.
The conclusion is very concise and only summarizes some of the most important contributions of the research. More discussion is needed.
The ideal combination of BA content and curing time is indicated but not clearly justified.
The lack of results for more curing time can be crucial to establish a correct RSM analysis. I consider it too short a curing time to know the correct behavior of BA for soil stabilization, and even more so when their low pozzolanic reactivity is indicated.
It would be advisable to use RSM analysis for multi-objective optimization, not only analyzing the response to unconfined compressive strength, but also other properties such as CBR, swelling, collapse, direct shear, etc. ....,
Author Response
Dear Sir/Madam,
The authors would like to thank the reviewer for the time and valuable suggestions. The reviewer's comments have been addressed and corrections have been made in the revised manuscript wherever necessary and highlighted accordingly. The response has been attached.
Thank you
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe paper presents the results of an experimental study focused on assessing the effect of biomedical waste ash (BA) on the unconfined compressive strength of a soft soil and to optimize the dosage of biomedical waste ash and the curing period (C) with varying quantities in order to maximize the unconfined compressive strength by applying response surface methodology. The study is very interesting but there are several issues requiring authors attention, namely:
i) it is written that the soil studied is a soft soil but the reviewer does not agree, it is a problematic soil but not a soft soil. A soft soil is typically a fine soil, normally with organic matter, exhibiting low permeability, low bearing capacity and high compressibility. The soil under study is a granular soil, more precisely a clayey sand, so, the authors must revise the soil classification. Moreover, as it is a granular soil it is important to know the void ratio of the samples, as well as the minimum and maximum void ratio of the natural soil;
ii) the sample preparation and experimental procedure is very incomplete. It is necessary to mention the samples dimensions; curing conditions (humidity, temperature, samples inside the moulds); OMC and MDD of all samples in order to understand how samples were prepared, keeping the same dry density (or porosity or void ratio) or moisture content, otherwise it is very difficult to interpret the results; ad finally, how the UCS tests were performed (what variables were measured during test, the tests were done with what constant strain or load rate, and in which testing machine):
iii) authors must justify why they chose the levels presented in Table 3 for the input variables;
iv) as it may be seen, the experimental design chose by authors is not a true testing optimization because all possible combinations of the two input variables were selected, i.e., 2 factors each one with 3 levels means 3 x 3 = 9 combinations, and all of them were considered in the study. Thus, the authors did not perform a true design of experiments aiming to reduce the number of tests, instead they studied all possible levels combinations for a specific input variables space;
v) in any statistical study it is important to have a final validation stage, in which 2 or 3 new tests are performed for new levels, within the operational space, different from the ones used in the first stage (during the development of the mathematical model).
The structure of the paper is good. The Introduction is scientifically valid but some sentences require up-to-date new references. As stated above, the experimental methodology must be improved. The discussion of results is scientifically valid and all results are properly interpreted. Figure 1 can be removed, while Fig. 3 is not mentioned in the text; Figures 8 and 9 can be merged in a single figure, side-by-side, or simply remove Fig. 8.; in Fig. 9 it is missing the real residuals of all centre points (only one is presented), the same happens with Fig. 7, only one centre point result is presented. In line 179 authors refer to Table 4 before talking about Table 3; moreover, Table 6 can be removed because it does not add nothing to the paper and it may be misleading by suggesting that there are several optimums (indeed, there is only one optimum that maximizes the UCS value). There are some citations throughout the text not included in the list of references (including standards).
Along the manuscript there are some mistakes, sentences that would benefit from a revision. The English quality is very good but minor improvements are required. Below there is a list of comments that require the authors' attention:
1) paper title: ‘… for untapped potential’ is not clear for the reviewer, so, it is suggested to remove this expression.
2) abstract: clearly identify that BA is the only stabilizer used.
3) citations in the text with missing references: lines 41 (Indian industry (CII) in 2010), 150 (Indian standards IS-2720), 172 (Indian standards IS-2720 Part VII-1965), 174-175 (Indian standards IS-2720 Part X-1991), 187 (Turkane et al., 2022).
4) introduction - lines 43-44: explain why the addition of Portland cement promotes the ‘… decrease in strength and high plastic shrinkage due to incomplete hydration’, because normally the addition of Portland cement promotes the increase of the strength of the stabilized soil.
5) introduction – lines 51-52: regarding geopolymers, there are other important references that may be cited here, e.g., https://doi.org/10.3390/app131810550 , https://pubs.acs.org/doi/10.1021/acs.est.0c02001 , https://doi.org/10.1016/j.conbuildmat.2020.120039 , https://doi.org/10.3390/su13073732 , https://doi.org/10.1016/j.jece.2021.107084 , https://doi.org/10.1016/j.jrmge.2021.06.007 , https://doi.org/10.1016/j.trgeo.2020.100385
6) introduction – line 108: define OPC (ordinary Portland cement ?).
7) introduction – lines 129-133: regarding the optimization techniques, there are other important references that may be cited here, e.g., https://doi.org/10.1016/J.JCLEPRO.2019.117766 , https://doi.org/10.1680/jgeen.19.00295 , https://doi.org/10.1016/j.conbuildmat.2020.120271
8) section 2.2 the sample preparation and experimental procedure: during the curing time and during the UCS test suction may develop with high impact on the unconfined compression strength measured. Please describe what were the procedures adopted to minimize suction effects.
9) section 2.3. Response Surface Methodology (RSM) – line 184: optimize or optimization process? Please verify.
10) section 2.3. Response Surface Methodology (RSM) – lines 194 and 196: in experimental design the input or independent variables are used referred as factors while the output or dependent variable is usually referred as response, so, instead of ‘output factor’ or ‘output parameter’ it must be response.
11) section 2.3. Response Surface Methodology (RSM) – line 226: instead of ‘was’ it must be were.
12) section 2.3. Response Surface Methodology (RSM) – lines 225-226: according to Tables 3 and 4 you have 4 vertices points, 4 axial intermediate points and a centre point with 5 replicas, please revise the sentence.
13) Table 4: what refers to the line 14 of the table, is it a validation test? How this particular test result was used in the paper or it was simply discarded from the analysis?!
14) section 3. Results and discussion – lines 274-275: perhaps it is better to say that the model fits well the input variables or factors.
15) section 3. Results and discussion – lines 277-278: please, revise the sentence because something is missing.
16) section 3. Results and discussion – line 279: remove the word ‘of’.
17) section 3. Results and discussion – lines 296-297: perhaps it is better to write ‘The effect of independent variables or input factors on the output response can be …’.
18) section 3. Results and discussion – line 315: after the word ‘factors’ replace the semicolon with a comma.
19) conclusions – lines 331-340: please revise the line spacing.
20) reference no. 49 Turkane, S. D., & Chouksey, S. K. (2022) is not cited in the text.
Comments on the Quality of English Language. The English quality is very good but minor improvements are required. as listed in the comments for authors.
Author Response
Dear Sir/Madam,
The authors would like to thank the reviewer for the time and valuable suggestions. The reviewer's comments have been addressed and corrections have been made in the revised manuscript wherever necessary and highlighted accordingly. The response has been attached.
Thank you
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe reference to figure 4, which has been included in the revised version, has not been inserted in the text.
If the primary objective of the study is "to assess the initial strength gain and earlystage reactions of the soil-ash mixture " as stated in the author_response, it should be indicated in the paper, to understand the selection of short curing periods.
Author Response
The authors thank the Reviewer for the valuable suggestions and comments.
All the suggestions have been incorporated in the revised manuscript.
The responses have been attached.
Thanking you.
Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe Reviewer thanks the authors for their replies, with valid scientific explanations. However, there are still few issues requiring authors attention, namely:
i) regarding the sample preparation it sees that the samples were prepared varying the initial dry density (or porosity or void ratio) as well as the initial moisture content, making very difficult to interpret the results. The authors are advised to read some papers related with the ratio porosity/cement ratio (n/Civ) proposed by Consoli and colleagues in several papers related to granular soils chemically stabilised.
ii) Figure 1 can be removed because it does not add nothing to the paper. A simple description in the text is enough.
iii) the Reviewer recognise that the representation of the residuals for all centre points might obscure the clarity of the presentation. Tus, the authors are advised to describe the residuals variability of centre points in the text, or in a better way, just present in the figure two small horizontal lines meaning the max and min of the residuals values for centre points.
Comments on the Quality of English LanguageMinor editing of English language required
Author Response
The authors thank the Reviewer for the valuable suggestions and comments.
All the suggestions have been incorporated in the revised manuscript.
The responses have been attached.
Thanking you.
Author Response File: Author Response.pdf
