Volume Stability of Cement Paste Containing Limestone Fines

Round 1

Reviewer 1 Report

Dear authors,
Thank you very much for this practical and useful scientific article.

The article is very well prepared. The title and abstract fully correspond to the content of the article.

The introductory chapter is prepared with the help of an extensive literary base.
Nevertheless, I would recommend expanding with the latest articles in the field of alternative SCM suitable for cement improvement:
10.1016/j.jobe.2021.103011
10.3390/ma14133674
10.1016/j.jobe.2021.102655

Descriptions of materials, samples and tests are prepared logically and understandably.

I really like your results, including their descriptions and extensive discussions.
There is a lot of work here and I appreciate it.

Note in chapter 3.6. You're talking about correlation here, but you're actually using linear regression and coefficient of determination R2. This is not a correlation evaluation, other calculation methods are used for it - please try to study and supplement it, or change the meaning of the paragraph.

Beware, I'm not saying that your results don't correlate, I guess so. But in terms of mathematical description, you are inaccurate.

I will give an example: the values ​​in Figure 18, for P10% have R2 equal to 0.69 - this means that the linear approximation is a moderate regression for these data, but the dry and chemical shrinkage data can still correlate to a high value - we do not know without calculation.

The conclusions correspond to the findings.

I'm afraid it is necessary to improve several photos and images graphically - they have a strange sizing.

There are sometimes textual inaccuracies and errors in the article - read it carefully.

Eg lines 115, 158, 531, etc.

Regards,

Author Response

Please see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

• In the abstract, the author said ‘Incorporating limestone fines (LF) as cement replacement can 5 control the shrinkage of the paste.’. This is not consistent with the experimental results. Please rewrite.
• In the Introduction part, the definitions of several shrinkage were presented in detail in the first paragraph. This part can be simplified and is far from the article.
• Many useless references were added, for example, ‘there is a substantial amount of research on chemical, autogenous, drying shrinkage and expansion of concrete and paste containing SCM [32-53]’. Little information was given from Refs [32-53].
• 1 and Fig. 2 should be combined into one figure.
• In Part. 2.3.2, The specimens were then placed in plastic bags. Is this treatment enough for sealing the specimens?
• For every shrinkage result, the unit should be in the form of ‘μm/m’ or ’10^-6’.
• Part 3.5 is useless. The difference among various volume deformation is well known.
• In Fig. 8, the chemical shrinkage of SL 10% is lower than that of SL 5%. Please explain.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

This paper is properly revised. 

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

Please find the comments below in the attached file.

Comments for author File: Comments.pdf

Reviewer 2 Report

The reviewer acknowledges the efforts undertaken by the authors to present an interesting study on the volume stability of cement paste containing limestone fine. The central idea of the article lacks novelty. Numerous researches with great insight details have been published previously on the same topic. The article merely compiles some haphazardly carried out investigation without strong discussion and analysis. Detailed comments are given below:

• The language of the article does not meet the journal publication requirements. Use of words like e.g. boost/boosted/boosting is frustrating. Boosting in shrinkage is not something good for concrete. Be cautious with your word selections. Line 394: A positive high!
• There is a dearth of references. Inferences are made without providing sufficient backing from literature.
• Line 48: Continuous expansion in water? Agreed, that concrete swells when cured in water. However, continual expansion is not true. Provide at least a couple of references to support your claims.
• The “highlight” of the paper is to understand the influence of LF on different forms of shrinkage. The size of the limestone particle used is quite coarse (D₅₀ >1mm). These particles cannot provide a nucleation site for hydration. Throughout the article the authors emphasize this fact numerous times. Moreover, the authors go on to say the limestone takes part in hydration reaction resulting in formation of carboaluminate phases, which is not possible considering the big particle size. No evidence/support is provided to validate the claim.
• The authors mention that reducing the particle size beyond a value is energy intensive (I agree). But is it more than the energy required to carry out the carbonation process at elevated temperature and pressure for a few hours to days? Even a rudimentary calculation would have supported their claim. That way at least some form of analysis would be present in the article.
• Figure 3: What is white coloured layer on the top of the cement paste? It looks like vials from previous experiments were used for the test. The test is extremely sensitive and using uncleaned/used vials could bring substantial changes in the results. Hence, creating a doubt on all the results provided in the article.
• Section 2.3.2 Autogenous shrinkage: Where were the samples stored after sealing them in the plastic bags? Line 157: To maintain high humidity? Is 80% high humidity or 99% high humidity? Please improve on these ambiguities throughout the article.
• Section 2.3.3: Until what age did you measure the drying shrinkage? On how many specimens?
• Line 205: If reaction of C3A and limestone is resulting in formation of voluminous carboaluminates than what is the reason for increase in chemical shrinkage? Higher the solid volume of the hydration products lower should be the chemical shrinkage.
• Why does the trend change for P15%? Did you try repetitions? Give some explanation for this.
• Line 219: What is the proof for acceleration of hydration? 1mm particles of limestone cannot provide acceleration. Also, the word “inferior” for density description is frustrating. The reasoning provided in lines 220-221 is not accurate.
• Line 228: WHAT? Expansion is due to slower hydration of cement? The higher drying shrinkage for limestone containing mixes is most likely due to higher and connected porosity.
• Lines 246 to 248: This makes no sense whatsoever. What is clumping? Internal reaction resulting in higher drying shrinkage???
• Lines 283-285: Hydrates absorb more water? What hydrates are you talking about? This is so wrong.
• Line 381: Why does chemical shrinkage decrease?

The article lacks sound technical discussion along with absence of appropriate experiment for validation of the claims. The reviewer suggests rejection of the manuscript in the current state.