Splitting Tensile Strength of Fly Ash-Modified Sand at Various Saturations and Curing Times

Round 1

Reviewer 1 Report

The manuscript presents the results from an experimental investigation on the effects of fly ash percentage, curing time and degree of saturation in stabilised sand. The work presented is clear and original. Manuscript is well-written and appropriately structured. However, there are some issues which needs to be resolved. 

1.       The introduction provides a summary of research on FA stabilised sand. However, it does not explain why split tensile strength is important. Why not other methods? Is there a particular application where split tensile strength is more relevant?

2.       Figures 3 and 4 are too small. Improve them and include more details.

3.       How did you measure void ratio?

4.       How did you achieve the predetermined Sr? Was the Sr was measured to verify?

5.       L151: “…CT of at least 20%...” This is not clear. Why CT is given as a percentage?

6.       Conclusion drawn in L186 – 188 is ambiguous and problematic. Where can we see this twenty-fold and fourteen-fold increment?

7.       L189: The reduction in qt after one month is not evident. According to Figure 6, 4 month strength is higher than one month strength at any Sr. (assuming the numbers 1, 2, 3, 4 in the legend refer to CT in months)

8.       L233-239: Provide evidence or reference to this argument.

9.       It is hard to make a meaningful conclusion from the comparison in Figure 13. The empirical equation (4) was derived using the experimental data. For example, k = 0.06 was obtained directly from experimental results. Then, when you compare the calculated value to the same experimental results, they are obviously going to match.

10.   Proof read the manuscript thoroughly for language corrections.  

Author Response

Dear Reviewer

Attached is the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

In general, the authors studied the splitting strength of sand stabilized using fly ash, specifically discussed the influence of the curing time and saturation on the mechanical splitting behavior of stabilized sand, and put forward a splitting strength prediction model considering various factors such as saturation and fly ash content. The research is very interesting and the the paper structure is well written, but there are also some problems. After revision, it can be accepted as a journal for publication. The specific problems are as follows:

 

1. In introduction section, the author mentioned that Chemical grouting as a binder has been widely used for soil improvement techniques to prevent liquefaction. There is too little introduction about the liquefaction of sand, and more references should be cited to introduce the liquefaction of sand, because there is too little analysis on why the sand should be treated using fly ash in this article, some recent references are as follows，it is very relevant to soil liquefaction for this research.

①　Cyclic undrained behavior and liquefaction potential of sand treated with chemical grouts and microfine cement (MC-500). Geotechnical Testing Journal, 17(2), 159-170.

②　A hybrid GMDH neural network and logistic regression framework for state parameter–based liquefaction evaluation. Canadian Geotechnical Journal, 99(999), 1801-1811.

③　Prediction of in situ state parameter of sandy deposits from CPT measurements using optimized GMDH-type neural networks. Acta Geotechnica, doi.org/10.1007/s11440-022-01540-6.

④　A novel PSO-KELM based soil liquefaction potential evaluation system using CPT and Vs measurements. Soil Dynamics and Earthquake Engineering, 150, 106930.

⑤　Promoting precipitation technique using bio-chemical grouting for soil liquefaction prevention. Civil Engineering Dimension, 22(1), 1-5.

 

2. In the first paragraph of the introduction, the author thinks that fly ash is one of the most environmentally friendly materials that can reduce environmental problems , before writing this sentence, the authors should give some curing agents for treating problematic soil, such as cement, lime, SEU-2, phosphogypsum, GGBS, etc, The following are some relevant references in recent 5 years:

①　Journal of Hazardous Materials, 2021, 415: 125659. https://doi.org/10.1016/j.jhazmat.2021.125659

3. In the sentence,’ As an industrial waste, fly ash (FA) has been determined to be an effective choice for increasing soil stiffness and strength by way of’，the word ‘industrial waste’ should be revised to ‘industrial by-products’. Fly ash is now considered as an additive of cement and is no longer an industrial waste.

 

4. In the introduction, some references of fly ash stabilized soil should be also cited.

for example:

 Environmental Earth Sciences, 80(3), 1-14. https://doi.org/10.1007/s12665-021-09398-9

 

5. The fitted curves in Fig.10 are incomplete and seem to be covered, please correct.

 

6. In section 2.11, please give the test standard of each indicator in Table 1.

 

7. In the sentence ‘after the mold was full, the surface was leveled and weighed to ensure that it was at the targeted relative density of 50±2%’. Why is the relative density determined as 50 ± 2% in this paper? Please explain it.

 

8. The picture size from Figure 4 is too small, please adjust it larger 

 

9. In the sentence ‘decreasing with ads in saturation’，what is ads?

 

 

10. In  Fig. 8a and b, the authors write that FA bonds are concentrated on the contact surface between particles or distributed on the surface, actually it only can be seen that the structure of Fig. 8a is more compact, please correct. In addition, some fly ash gel can be seen in the Figure.8, the term ‘FA bond’ should be changed to ‘gel’.

 

11. It is suggested to replace FA in formula (3) with other symbols. FA is generally the abbreviation of fly ash.

Author Response

Dear Reviewer

Attached is the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript submitted by Minson Simatupang et al. investigates the mechanical properties of fly ash-solidified soils. The manuscript is well written, the experimental design is well planned, the experimental results and empirical formulas are described, and it has some engineering significance. However, there are still some places that need to be clarified or modified by the author, as shown in the following 6 items. It is suggested to accept it after major revision and publish it in this journal.

1.The introduction of the splitting equipment cannot be seen in the author's manuscript. It is recommended that the author give a further detailed introduction to the splitting equipment.

2. Figure 3 and Figure 4 are too small and not clear enough.

3.From Figure 5, it can be observed that there is a certain relationship between the CT of the sample and the dosage, and the change is most obvious at 20% dosage. It is recommended that the author make further explanations.

4.Some of the illustrations in Figure 7 are not clear enough, and the author is advised to replace the symbols.

5.Only the content of SEM is described in the manuscript, and the author is suggested to do further analysis on the part of the reaction mechanism.

6.The large number of numerical points about the fitting in Figure 13 are not clear enough, and the author is advised to express it more clearly.

7. The key conclusion discussion is missed in the manuscript, and what are the differences between the author's research results and previous fly ash solidification experiments. Please revise and discuss in detail in the comparison table.

Author Response

Dear Reviewer

Attached is the revised manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Accept

Reviewer 3 Report

The authors have fully revised the manuscript and  addressed the reviewer‘s concerns.