Comparative Research on Mechanical Properties and Void Distribution of Cement Stabilized Macadam Based on Static Pressure and Vibration Compaction

Round 1

Reviewer 1 Report

The work is original and important from the point of view of transport engineering and practice, but not well described. The first part of the article with the introduction does not contain complete description of the subject matter of the article and requires improve.

There is no description of other methods of preparing stabilized samples and the analysis of the applied energy, e.g. Proctor method, vibrating table method, which are used in the world.

The authors did not provide a clear analysis of the compaction energy. Two methods of sample compaction with diametrically different energy were compared: 2687 kJ/m³ and 4700 kJ/m³, which of course generates different test results that are incomparable with each other. It would be valuable to present graphs of dry density versus moisture content (test sequence of the  determination of the optimal moisture content) for both compared methods, static and vibrating.

The article informs how the mixture was vibrated to 98% (90s), but there is no information how this compaction was achieved in a static method. Moreover, what was the in situ compaction coefficient, according which method?. This should be completed and explained.

It has been shown that higher compaction energy is required for the preparation of samples with respect to the samples taken from the construction site, it is a new and important content providing to science. This provides the basis for correcting the energy values ​​for cement stabilized macadam sample preparation.

The second part of the article on the size and amount of free spaces is interesting and brings new knowledge to science. This allows for a comprehensive comparison and analysis of the effectiveness of the methods of thickening cement materials.

Detailed Notes:

3. 3.2 Only 7-day macadam strength was analyzed, while all over the world, 28-day strength is used for cement mixtures. It would be good to complement this.

Bad description in table 5: insert “percentage passing” instead of "through".

Bad description in table 4: 1 #, 2 # ...... etc. “Composition of the mixtures” instead of the “gradation”.

Bad layout of the header of table 7 is unreadable in this form.

The Fig. 5 shown show the distribution and size of pores in the compacted mixture indicate trends and show the differences in the compaction methods used. It would also be worth presenting statistical data: mean, median, max. min. etc. which would enable better analysis.

Table 10, missing units and data description.

Improve English is required.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

   Cement stabilized macadam semi-rigid base materials are the most broadly used materials in the construction of roads. Preparing these materials by vibration compaction method and static pressure molding method is a great challenge in order to determine accurately the material properties and provide a useful tool in road engineering design.

   I found the paper to be overall well written and much of it to be well described. On the other hand, I have a few concerns about the paper which are presented below:

1. In section 2.2.2 entitled “Comparative analysis of the two methods” the two methods of compaction were compared. But in lines 114 through 118 only vibration method was referred in order to determine the moisture content. I would suggest also mentioning about the way of determining the moisture content by using static pressure compaction method.
2. In lines 164 through 168 some theoretical explanations should be given in order to justify the results of the maximum dry density and the optimal moisture content in XM and GM methods.
3. It is not clear to me why fractal dimension of voids obtained by static pressure was higher than that vibration compaction in lines 334 through 339. Please justify this result.
4. In section 4 entitled “Conclusions” I would suggest adding a paragraph in which you will conclude that the vibration compaction is the most reliable method of simulating the properties of base materials and you will propose it as an effective method in road construction.

Author Response

Please see the attachment.

Author Response File: Author Response.docx