Experimental Investigation on Fracture Behavior and Mechanical Properties of Red Sandstone Subjected to Freeze–Thaw Cycles
Round 1
Reviewer 1 Report
This study shows very useful results and summary of the effect of freeze-thaw cycles for the red sandstone. The analysis from this paper had implied a regression relationship about the freeze-thaw effect and rock strength. Following are comments that could add more information about the study's contribution.- For sampling, it will be useful to know the origin of samples, i.e., from the same rock mass or from different locations and different depths. If from the same original rock mass, describing the intact status of the rock mass before sample coring would provide the initial conditions for comparison.
- Based on the analysis results, what is practical condition of the original rack mass (red sandstone), i.e., the effect of freeze-thaw cycles if any.
- Before the test, the pattern of micro cracks on the surface of rock mass and samples should be described and compared with the post-test crack pattern.
- It will be informative if the authors can suggest when to consider the effect of confining pressures at the site.
- For freeze-thaw cycle, the influence of time used for freezing and thawing should be addressed and, if any, add the necessary literature to explain the test design, like the 4 hr and 10 hr cycle.
- I suggest that add the results of slake durability test, if any from the literature, of red sandstone, and compare that with the results of freeze-thaw tests.
- Figure 9, the micro cracks are not clear in the photos. The authors could highlight them if possible.
Author Response
Great thanks for the reviewer’s valuable comments. Each comments is explained in detail as follow:
- For sampling, it will be useful to know the origin of samples, i.e., from the same rock mass or from different locations and different depths. If from the same original rock mass, describing the intact status of the rock mass before sample coring would provide the initial conditions for comparison.
Response: the initial conditions of the origin samples are added in detail.
- Based on the analysis results, what is practical condition of the original rack mass (red sandstone), i.e., the effect of freeze-thaw cycles if any.
Response: the practical condition of the testing samples are added in the paper and described in detail
- Before the test, the pattern of micro cracks on the surface of rock mass and samples should be described and compared with the post-test crack pattern.
Response: thank you for the valuable suggestion. In figure 9, the micro cracks of the untreated samples are present and compared with the treated samples.
- It will be informative if the authors can suggest when to consider the effect of confining pressures at the site.
Response: the condition in which should consider the effect of confining pressures are added in this paper.
- For freeze-thaw cycle, the influence of time used for freezing and thawing should be addressed and, if any, add the necessary literature to explain the test design, like the 4 hr and 10 hr cycle.
Response: the relevant literatures are added in the paper to explain the test design.
- I suggest that add the results of slake durability test, if any from the literature, of red sandstone, and compare that with the results of freeze-thaw tests.
Response: thank you for your valuable suggestions. The author will consider to perform a series of slake durability tests of red sandstone and analysis the results in the future.
- Figure 9, the micro cracks are not clear in the photos. The authors could highlight them if possible.
Response: the pictures in the middle illustrate the micro cracks induced by the freezing-thawing cycles. A large number of micro cracks occur and developed. If all the micro cracks are highlighted, the pictures will be chaotic.
Reviewer 2 Report
Good experimental work. We recommend to continue with increasing the number of freezing-thawin cycles, because during transitional autumn-winter and winter-spring periods (day-thawing-night freezing) the number of such cycles is up to 15-20. That is, the presented results can occur already during one year. Therefore, the characteristics of frost resistance for various materials in the normative literature are set at 200, 300 and more cycles of freezing-thawing
Author Response
Great thanks for the reviewer’s valuable comments. Each comments is explained in detail as follow:
Good experimental work. We recommend to continue with increasing the number of freezing-thawin cycles, because during transitional autumn-winter and winter-spring periods (day-thawing-night freezing) the number of such cycles is up to 15-20. That is, the presented results can occur already during one year. Therefore, the characteristics of frost resistance for various materials in the normative literature are set at 200, 300 and more cycles of freezing-thawing
Response: Thank you for your valuable comments. The place where the samples collected has not long transitional time. But the authors will consider to perform more experiments as reviewer suggested.
Reviewer 3 Report
Dear authors,
Congratulations for your work. It is an interesting approach of the subject. Generally, the paper is well written, but in some situations some explanations and minor changes are needed.
Some remarks
Page 2, line 6, I suggest replacing “Another” by “Other”
Page 2, last line, before Table 1 caption, you give the value of 15.8% for other minerals. What kind of minerals, or there are so many, and the quantity of each mineral is negligible?
Indicate the model of device used to determine a property or image, for example specify the equipment and the cathode used for X-ray, SEM microscope with accelerating voltage, for heat test camber specify the model and not “as shown in fig 2”…
Figure 2, I suggest renouncing to pictures of devices, I don’t see the added value to the paper.
Page 6: the value for mass loss I suggest writing “about 1.8% in mass and 3.0 % in density” as they are average values.
Tables 2 and 3 are a little bit confusing, please draw lines to define clear the set of results for each cycle.
What happens with samples on which a confining pressure of 20MPa was applied? Curves in figure 7 c (especially for untreated and after 30 cycles) looks different compared to the rest. The failure take place immediately after the maximum value is reached for that 2 samples, but not for the others. Do you have any explanation?
Best regards,
Author Response
Great thanks for the reviewer’s valuable comments. Each comments is explained in detail as follow:
- Page 2, line 6, I suggest replacing “Another” by “Other”
Response: the word is revied.
- Page 2, last line, before Table 1 caption, you give the value of 15.8% for other minerals. What kind of minerals, or there are so many, and the quantity of each mineral is negligible?
Response: figure 1 illustrates the proportion of the main minerals within the testing samples. The others include so many kinds of minerals, which only have a small quantity, i.e. 4.2 % feldspar and 3.5% calcite.
- Indicate the model of device used to determine a property or image, for example specify the equipment and the cathode used for X-ray, SEM microscope with accelerating voltage, for heat test camber specify the model and not “as shown in fig 2”…
Response: the model of the devices utilized in the research are specified as reviewer suggested.
- Figure 2, I suggest renouncing to pictures of devices, I don’t see the added value to the paper.
Response: Figure 2 illustrates the experiment procedures and the devices used in the each steps. It is helpful to improve the reliability of this paper.
- Page 6: the value for mass loss I suggest writing “about 1.8% in mass and 3.0 % in density” as they are average values.
Response: the sentence is revised as reviewer suggested.
- Tables 2 and 3 are a little bit confusing, please draw lines to define clear the set of results for each cycle.
Response: the table 2 and 3 are redrawn as reviewer suggested.
- What happens with samples on which a confining pressure of 20MPa was applied? Curves in figure 7 c (especially for untreated and after 30 cycles) looks different compared to the rest. The failure take place immediately after the maximum value is reached for that 2 samples, but not for the others. Do you have any explanation?
Response: by carefully check the test results, the figure 7c was has been redrawn.
