Effect of Freeze–Thaw Cycles on Mechanical and Microstructural Properties of Tailings Reinforced with Cement-Based Material
, Yunbing Hou 2, Dong Han 2,3, Xing Zhang 2,4, Shuxiong Cao 2 and Chunqing Li 5
Round 1
Reviewer 1 Report
The theme of the article is of importance and attracts attention as well. However, this research paper is more a work in progress than a finished product. Unfortunately, it does not conform to the journal requirement at this stage. It is necessary to overhaul editing and resubmit.
It can be briefly summarized as follows.
- The abstract should propose the research purpose, necessity, and summary of the research
- Combined table 1 and 3, table 2 and 4.
- The grain size distribution of slag should add in Figure 1 to compare with tailings.
- why just consider the 0 to 20 cycles?
- The paper just give out test results but gave no reason why.
Author Response
Thank you for the comments and suggestions of the reviewer, I will answer the following questions point-by-point.
1.The abstract should propose the research purpose, necessity, and summary of the research
Response 1:
The abstract has been revised, the necessity of the research is in lines 15-22, the summary of the research is in lines 25-32, and the purpose is in lines 32-35.
2.Combined table 1 and 3, table 2 and 4.
Response 2:
Tables 1 and 3 have been merged in line 128 of the paper, and the title has been changed to Grain size distribution of NCM and tailings. Tables 2 and 4 have been merged in line 129 of the paper, and the title has been changed to Main mineralogical compositions of NCM and tailings.
3.The grain size distribution of slag should add in Figure 1 to compare with tailings.
Response 3:
The mechanically ground slag has hydration activity，and can be used as the main component of the cementitious material to participate in the hydration reaction in the process of cementing the tailings. The fine slag particles can also be filled in the voids of the tailings to enhance the mechanical properties of the cemented tailings. These functions of slag have been tested by the authors and published in reference 32. The specific surface area of slag is 475 m2/kg. The main research of the paper is the change of the mechanical properties of the cemented tailings, after adding the cementitious material to the tailings and undergoing freeze-thaw cycles. It is not necessary to compare the particle size distribution of the tailings and slag. The Figure of Grain size distribution of tailings in this paper is visually shows its poor gradation (Cu=3.73, Cc=0.89). In order to make it have stable physical and mechanical properties, it needs to be cemented.
4.why just consider the 0 to 20 cycles?
Response 4:
The experimental study found that after 20 freeze-thaw cycles, the mechanical properties of the cemented tailings were stable, so only 20 freeze-thaw cycles of the results were presented and discussed in the paper. The mechanical properties of the cemented tailings may also be affected by other factors, such as the amount of cementitious material and the confining pressure of the cemented tailings. Next, we are going to study the amount of cementitious material and confining pressure on the stability of the cemented body in a low temperature environment. Find out the correlation among them, and to determine under what conditions the amount of cementitious material should be increased, what circumstances the tailings dam should be strengthened, or both should be carried out at the same time.
Future research prospects have been supplemented in the lines 483-495 of the paper.
5.The paper just give out test results but gave no reason why.
Response 5:
The experiments involved in the paper are all basic researches, the purpose of which is to provide technical support for the implementation of tailings consolidation discharge in cold regions, and the paper explains and analyzes the results of each test. For example, the analysis of the mechanical properties of the cemented tailings is in lines 199-209, 211-221, 224-240, 242-259, 262-267. The analysis of the crystalline phases of the cementitious material is in lines 281-286. The analysis of the amount of hydration products of the cementitious material is in lines 305-317, 320-329. The analysis of the surface morphology of the cemented tailings destroyed by freeze-thaw cycles of the samples is in lines 357-362, 364-369, 370-381. The analysis of the Pore size distribution of the cemented tailings is in lines 403-417, 420-440, 458-463.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Minerals-1598203 «Effect of Freeze-thaw Cycles on Mechanical and Microstructural Properties of Tailings Reinforced with Cement-based Material»
Pengchu Ding, Yunbing Hou, Dong Han, Xing Zhang, Shuxiong Cao and Chunqing Li
Comments
Major comment
- The practical value of the study is not entirely clear. Under real conditions, in one season from November to March, the ambient temperature varies over a wide range many times. How informative are differences in strength at certain amounts of a day of curing and at certain temperatures? How can the results of the study be used in real tailings dams? This aspect should be discussed in detail.
Minor comments
- What was the origin of the tails used for the experiments?
- Lines 113 – 114: on what basis was the ratio 14:6:10:70 chosen?
- Table 3: the title of the Table does not quite match its content.
- Tables 2 and 4: these are not chemical properties, but mineralogical compositions.
- Tables 2 and 4: how the mineralogical compositions were determined with an accuracy of one decimal place? XRD analysis does not provide such an opportunity.
I recommend a minor revision of the manuscript.
Author Response
Thank you for the comments and suggestions of the reviewer, I will answer the following questions point-by-point.
1.The practical value of the study is not entirely clear. Under real conditions, in one season from November to March, the ambient temperature varies over a wide range many times. How informative are differences in strength at certain amounts of a day of curing and at certain temperatures? How can the results of the study be used in real tailings dams? This aspect should be discussed in detail.
Response 1:
From the results of this paper, low temperature has a significant impact on the cemented tailings. Under the same conditions, the lower of the temperature, the greater damage to the cemented tailings. The main reason is that the low temperature makes the hydration process of the cementitious material very slow and cannot produce enough hydration products to cement the tailings. In the application of real tailings dams, when the ambient temperature drops to a certain value, we can consider taking thermal insulation measures for the tailings dams or increasing the amount of cementitious material to promote its hydration reaction. The freeze-thaw cycle creates cracks in the cemented tailings, and the tailings dam is in danger of dam failure, we can reinforce the tailings dam to make the tailings dam stable and durable.
Temperature may not be the only factor for the change in strength. Next, we are going to study the amount of cementitious material and confining pressure on the stability of the cemented tailings in a low temperature environment. Find out the correlation among them, and to determine under what conditions the amount of cementitious material should be increased, what circumstances the tailings dam should be strengthened, or both should be carried out at the same time.
Future research prospects have been supplemented in lines 483-495 of the paper.
2.What was the origin of the tails used for the experiments?
Response 2:
The tailings originate from Lilou Iron Mine in Anhui Province, and the information has been supplemented in line 111 of the paper
3.Lines 113 – 114: on what basis was the ratio 14:6:10:70 chosen?
Response 3:
The ratio of this substance is determined by experiments. It is described in detail in reference 32 and has been marked in line 117 of the paper.
4.Table 3: the title of the Table does not quite match its content.
Response 4:
Tables 1 and 3 have been merged in line 128 of the paper, and the title has been changed to Grain size distribution of NCM and tailings
5.Tables 2 and 4: these are not chemical properties, but mineralogical compositions.
Response 5:
Tables 2 and 4 have been merged in line 129 of the paper, and the title has been changed to Main mineralogical compositions of NCM and tailings.
6.Tables 2 and 4: how the mineralogical compositions were determined with an accuracy of one decimal place? XRD analysis does not provide such an opportunity.
Response 6:
The mineralogical compositions were provided by the Key Laboratory of Orogenic Belt and Crustal Evolution of the Ministry of Education of Peking University, and the X-ray fluorescence spectrum analysis experiment was performed, which has been supplemented in lines 130-131 of the paper
Author Response File: Author Response.pdf
Reviewer 3 Report
The resolution of Figure 1 is low. Please replace the Figure with a higher resolution.
Author Response
Point - The resolution of Figure 1 is low. Please replace the Figure with a higher resolution.
Response :
We have replaced Figure 1 with a higher resolution.
