The California Bearing Ratio and Pore Structure Characteristics of Weakly Expansive Soil in Frozen Areas
Round 1
Reviewer 1 Report
Page 1 - The compaction degree of soils K parameter needs to be clarified.
Page 2 - “However, there is insufficient high-quality soil to replace expansive soil. In Jiamusi, a better quality is found as compared with that of other weak expansive soils for the plastic index of the weak expansive soil, 16.2%. of silty fraction (Diameter in the range of 0.063 to 0.002 mm). The value of plastic limit = 27.6% also suggests the presence of silt, confirmed by the quantity of fractions above 0.005 mm (in accordance with ISO 14688‑1: 2018 - Clay (Cl) ≤0.002).
Page 3- Table 1. Basic physical parameters of tested soils -Specific gravity should be replaced by the standard term of ISO 17892-3: 2015 - particle density. It is important to indicate the unit of physical parameters, which in this case is most likely g/cm3.
Page 3- last paragraph- What standard procedure is used for compaction? Please specify a standard.
Page 3- Reference 17 is not selected appropriately. The standard procedure for processing the samples can be conveniently indicated.
Page 4 - Table 4. The samples prepared for tests. The units of used compaction energy of samples should be specified.
Page 4 - paragraph 2.3.2. CBR Testing for Soils under Different Freezing-thawing Cycles - first paragraph - The unit and designation of dray density rd should be specified (for example g/cm3)
Page 5 - It is not possible to assess whether the selected reference [22] is appropriate.
Page 5 - where ks (μm2) is the permeability of the soil. What is this parameter, if it is a coefficient of permeability then it has a physical unit of velocity?
Page 6 - paragraph 2.4.3. Sample Preparation for Different Compaction Degrees and Freezing-thawing Cycles Testing - At what compaction work are the accepted compaction degrees of 80%, 90%, 95% and 100% determined?
Page 8 - Figure 4. Compaction curve of samples under different compaction energies - This figure lacks important designations:
- What compaction work are the individual tests. A diagram of dry density and compaction work can also be indicated;
- What is the designation Va;
- The unit of dry density should be written correctly.
Page 8 - Figure 5. Curve of compaction degree and stroke number under different moist contents. - Please check these results because the materials do not submit to compaction at water contents close to the liquid limit.
Page 8 - Please clarify the abbreviation NMR.
Page 10 - In Figures 7 and 8 the designations for the units should fit in the context of established practice for example so [m].
Page 11 - References [33, 34, 35 and 36] refer to sandstone studies and not to dispersed soils.
Page 15 - Figure 16. The relationship of CBR value and number of NFT cycles. The fact is that materials with higher levels of compaction show lower CBR values.
Page 19 - Conclusion 1 - I propose to rework the text, emphasizing the influence of dry density and the number of cycles on the value of CBR test result. In this way the emphasis will be on the control parameter of the CBR test and its change with the change of the water content of the material.
Page 19 - conclusion 2 - The first two sentences state certain facts in the behaviour of the dispersed medium and the surface activity of the water. I recommend that this conclusion be transformed with an emphasis on the studied effect of the number of freeze-thaw cycles on the CBR value.
Page 19 - Conclusion 4 - The results of the CBR laboratory and field test are a convenient and fast tool for estimating the density of materials. Given the high load speed (1 mm / min) in the CBR test there is not enough time to dissipate the pore pressure and this creates the impression of higher material strength. This feature must also be taken into account when working with fine-grained soils.
Author Response
Please see the attachment.
Reviewer 2 Report
- Overall this paper is written in poor English, which makes it difficult to understand. Professional proof-reading by a native English speaker is very strongly recommended.
- Method: Please clarify the method of sample saturation after the freez-thaw cycles. Also include a rationale why the CBR samples were saturated before testing.
- Presentation of data: the expansion strain needs to be reported before the presentation of NMR and CBR results, otherwise these resuklts cannot be fully understood.
- The authors should also comment on the formation of ice lenses; please clarify why you think it unnecessary to consider ice lenses in the road sub-base in this area.
- Discussion: the paper does not include a discussion (i.e. a comparison of the presented results with literature data). This needs to be included.
- Please consider the comments in the attached document.
Comments for author File: 
Comments.pdf
Author Response
Please see the attachment.
Author Response File: 
Author Response.docx
Round 2
Reviewer 2 Report
I have taken the author's wish to keep the focus of the paper as it is into account. However, there are several points that must be addressed:
- The language is still very poor, and the frequency and severity of grammatical error make the paper difficult to read and lead to misunderstandings. For example, it is not clear if the “weak expansive soil” in the paper refers to a “weak soil” or a “weakly expansive soil”.
- The authors need to include a rationale for using different saturation methods for NMR samples (vacuum saturation and soaking) and CBR samples (soaking).
- It appears that the NMR samples were frozen after saturation and the CBR samples were frozen before soaking in water. The change of port size distribution is potentially very different for these different methods. The authors need to explain why they consider the change of pore structure comparable in both sample types.
- The authors must be very clear throughout the paper if they talk about expansion due to freeze-thaw or expansion due to soaking in water.
- The authors should present a graph of the CBR data vs. the void ratio after soaking for all samples. This will demonstrate if there is a difference between samples that expanded due to freezing and samples the expanded due to soaking.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
