Dynamic Compression Properties of Ni-Fe Slag Powder Soil Cement under Impact Load
Round 1
Reviewer 1 Report
Please see the attaced review file.
Comments for author File: 
Comments.docx
Author Response
1.Abstract:
Some numerical results of SHPB tests should be provided in the abstract.
Answer: Correction has been made in the revised version.
The results show that under the same age and different admixture conditions, the dynamic stress of Ni-Fe slag powder soil cement increases first and then decreases and reaches the maximum when the admixture ratio is 40%, and the dynamic stresses at 7d, 28d and 60d were 5.10 Mpa, 9.73 Mpa and 13.51 Mpa respectively.
- Introduction:
The introduction should contain a very concise overview of Ni-Fe slag: how it is generated, what minerals it consists of and what problems are related to its disposal/reuse. Also, what benefits can addition of this slag to cement create and what is the scientific novelty of authors’ approach described in the current study.
Answer:Correction has been made in the revised version.Line 46-50.
“Ferronickel slag is a metal waste product produced by smelting steel or nickel. Generally, it is dumped as sand containing fine powder, which is nonbiodegradable. Nickel-iron slag can be used as a raw material for the preparation of slag cement, which can be used as a substitute for cement under specific conditions, and has signif-icant environmental benefits in the practice of mineral slag utilization[17]”
- Materials and methods
Soil: provide the mineralogical composition of soil, including the content of organic matter.
Correction has been made in the revised version.But we are very sorry for that the organic matter content cannot be testedsince the authors have lost the samples.
The main components contained in the soil are SiO2, Al2O3, Fe2O3, and these components account for more than 50%. In addition, it also contains a small amount of CaO, MgO, Na2O, K2O and other components.
The main components contained in the soil are SiO2, Al2O3, Fe2O3, and these components account for more than 50%. In addition, the soil also contains a small amount of CaO, MgO, Na2O, K2O and other components4. Slag: how fine ground it was?
Answer: Correction has been made in the revised version.
“The particle size distribution of nickel-iron slag powder and ore powder are 0.27μm~4.38μm and 0.65μm~5.23μm respectively.”
- Lines 121-126: Are these assumptions based on the results of the current study or earlier literature? Please provide a cross-reference to the section of the manuscript where it is discussed in detail, or provide a literature reference.
Answer: Correction has been made in the revised version.
“[22] F. Chen, S. Tong, "Effect of Ferronickel Slag Powder on Strength of Soil in Marine Environment," Advances in Civil Engineering, vol. 2020, pp.1-10, 2020.”
- Lines 166-168: I would like to see a more in-depth analysis of chemical processes related to hydration of Ni-Fe slag.
Answer: Correction has been made in the revised version.
“Portland cement in soil-cement contains a large number of mineral components, such as C3S, C2S, C3A, and C4AF. So, the cement undergoes hydration reactions upon contact with water, resulting in the formation of a weak alkaline environment within the cement soil. At the same time, ferronickel slag powder contains a large number of potentially active vitreous substances, including SiO2, Al2O3, and Fe2O3[20]. Under the weak alkali environment, vitreous substances can give better play to the chemical activity effect and produce hydration products such as C-S-H, C-A-H, CaO·Fe2O3·mH2O, Aft, and AFm.”
7.Lines 181-182: Significance should be proven by p-values. The manuscript would benefit from more extensive use of statistical data processing to interpret the results and draw the conclusions.
Answer:Due to the limited knowledge of the author and the rush of time, we are very sorry that we have not been able to conduct a deeper analysis of this issue.
- Figure 3: Consider showing the error bars.
Answer:The error bars have been added in the revised manuscript.
- Provide the type and the main characteristics of the apparatus. How the samples were prepared and how the SEM observations were performed?
Answer: Correction has been made in the revised version.
“the QUANTA250 multifunction scanning electron microscope for tungsten filament (SEM)”
“In this SEM test, the samples were taken from the range of 2cm~3cm from the surface of the test block, and the observation surface of the selected samples was as flat as possible. Two test groups with the most typical Ni-Fe slag powder admixture ratio of 0% and 45% in cured sandy soil were selected, and the curing age was set at 7 d and 60 d.”
10.Figures 5 and 6: Show the scalebars.
Answer:The original HD image has a scale.
11.Conclusions: What are the practical implications of your study? How it contributes to solution of problems related to Ni-Fe slag, and increase in the slag reuse? Also, what are the main implications in geotechnics?
In recent years, China has discharged about 40 million tons of ferronickel slag each year, accounting for about 20% of the total discharge of metallurgical slag. However, the comprehensive utilization of this slag in China is currently low, and the main treatment methods are piling or landfill treatment, which not only occupies a large amount of land area, but also causes serious damage to the environment.
Nickel-iron slag powder is inexpensive, and if it can be used as admixture in cement soil, not only can the resources be fully utilized, but also can reduce the construction cost. In this paper, the mechanical properties of nickel-iron slag powder hydromulch under dynamic environment are studied, and the better admixture value of nickel-iron slag powder is 40%, which can provide reference for engineering design.
Author Response File: Author Response.docx
Reviewer 2 Report
The research is dedicated to soil consolidation, in particular, the influence of partial replacement in the composition of ОРС by Ni-Fe slag and duration of solidification on dynamic compression properties of consolidated soil under impact load.
The results of the research are interesting and useful in terms of scientific and practical values, because the reduction of contents of Portland cement, the production of which is a source of CO2- emissions, is very important.
Some comments:
1. Table 4. The values of peak strain in the table should be expressed in the same units of measurements as in Fig.1 (for better understanding).
2. The phases that have been identified in the process of cement hydration these are: CSH gel, calcium hydroxide and calcium carbonate, should be shown in Fig.5 and Fig. 6.
Author Response
Some comments:
1.Table4.The values of peak strain in the table should be expressed in the same units of measurements as in Fig.1 (for better understanding).
Answer: Correction has been made in the revised version.
2.The phases that have been identified in the process of cement hydration these are: CSH gel, calcium hydroxide and calcium carbonate,should be shown in Fig.5 and Fig. 6.
Answer: Correction has been made in the revised version. The main hydration products of the cement soil have been shown in Figure 6 (typical SEM of NiFe slag powdered cement soil).
Author Response File: Author Response.docx
Reviewer 3 Report
The authors have tested and analyzed the response of Ni-Fe Slag Powder Soil Cement under dynamic stresses.
From the reviewer's viewpoint, the manuscript is well written and organized. The results are clearly readable and reasonable when compared with international codes.
Author Response
Thank you very much for your hard work and consideration on publication of our paper. My co-authors and I would like to express our great appreciation to the editor and reviewers.
Thank you and best regards.
