Improving Concrete Infrastructure Project Conditions by Mitigating Alkali–Silica Reactivity of Fine Aggregates

Round 1

Reviewer 1 Report

The work deals with the important issue of the influence of two mineral additives: fly ash and silica fume on the reduction of ASR-induced expansion. The effect of these two additives, which were introduced in the amount of 15 and 30% of the cement mass, on the reduction of expansion caused by the reactivity of three types of fine aggregates was analysed. The work should be supplemented with:

1. A more extensive review of the literature on the effect of mineral additives on ASR and recommended amounts of these additives. The introduction describes the basic information on the ASR too extensively and focuses less on the information related to the subject of the paper.

2. Information on: aggregate - reactive components are not indicated, mineral additives -chemical composition is not shown, cement - chemical composition and alkali content are not shown.

3. It should be indicated what w/s coefficient was used in mortars and how the consistency of mortars with mineral additives was shaped. Why were 15 and 30% mineral additives selected?

4. It is incomprehensible how graph 10 differs from 11 - both graphs show the same information, i.e. percentage decrease in mortar expansion

5. It should be explained why the expansion of mortars with less fly ash is smaller than the expansion of mortars with more fly ash. Have the standard deviations of the expansion values been determined?

6. The effectiveness of the mineral additives used should be clearly linked to the degree of reactivity of the aggregate used. It would be good to refer the results to the mineral composition of the aggregates used.

7. It seems that the recommendations contained in point 5 are not related to the subject of the work, because the work focuses on the use of a well-known method of testing the effectiveness of mineral additives - according to ASTM C1567. The recommendations indicated "More reliable testing techniques should be developed to predict ASR with higher accuracy" which the author does not consider in this work.

Author Response

1. The literature review section is reviewed to be more concise. Reviewer #1 is asking for extending the literature review while reviewer #2 is asking to shorten the literature review.
2. The aggregate is a river-based source as added to the manuscript. However, the chemical composition was not considered in this study as these aggregates are already in use by the State Department of Transportation. So, the research was conducted using there aggregates regardless to their chemical composition. It is a good idea  to consider doing future testing after considering this data.
3. Water-to-cement ratio of the AMBT fabricated and used in the test is added to the manuscript. The percentages of SCMs used (15% and 30%) are also added to the manuscript to justify the selection of these percentages.
4. Graphs #10 and #11 contains similar information. However, graph #10 (which is now graph #7 in the revised manuscript) shows the percentages of expansion reduction by categorizing the AMBT tests using aggregate type, while graph #11 (now graph #8 in the revised mansucript) categorize the data of reduction in expansion accordong to the type and percentage of SCM used. This difference in categorization between the two graphs are to visually support the explanation presented within the manuscript.
5. Fly ash expansion seems to level regardless to the percentage for fly ash amounts ranging from 15% to 30%. If you notice through all results, 15% and 30% fly ash percentage of expansion reduction are almost the same. Results shown represent the average measure of 3 AMBT bars for every SCM type and percentage. This is the minimum number of bars required by the ASTM. Since 3 bars are used, standard deviation was not calculated.
6. As indicated in point #2, the aggregate mineral composition was not analyzed.
7. The recommendation for future research section is completely revised. The statement of concrete regarding "more reliable testing method" is removed form the manuscript as recommended.

Reviewer 2 Report

Dear Author,

The article entitled “Improving Concrete Infrastructure Projects Conditions by Mitigating Alkali-Silica Reactivity of Fine Aggregates” deals with the experimental investigation on expansion rate of accelerated mortar bars (AMBT) and SCM added mortar bars.

The subject of the article could interest the readers off the journal. However, it needs major revision on some details.

The English of the paper is good, it is easy to understand, and the structure of the paper is clear and consistent. There are only few things to correct.

The title informative, the keywords are general, but enough. It would be advised to take out “moisture” as the article is not really dealing with it.

Abstract is a bit long and do not need to repeat the general description of ASR reaction as it is explained in details in the introduction part. It is also too general and should summarize the experiment and its results.

Introduction is also long and going into details, which might go beyond the scope of this research, or just going too far in history.

The number of the pictures and figures can be decreased and the figure captions should be more informative. Figure 3. and 4. need scales as they are microscopic photos. Or if they are from literature then reference needed. Figure 5. contains 6 pictures, which are all numbered but not explained what they depict. Table 1 is not necessary but if it is included, then reference needed.

The author should explain why the silica fume (SF) and class c fly ash (FA) were chosen as SCMs (there are many other possibilities). It is okay that the F1, F2, F3, fine aggregates are from local sources, but local to whom. Are those fine aggregates of which origin (river, sea, glacial…???), that is also important information.

The explanation of the method is detailed and understandable.

The results of the two experimental investigations are clear, shown nicely on the diagrams, but should be explained in more details in the text. Phase 2 experiments are also nicely represented on diagrams, but not explained in a manuscript.

However it is mentioned that there are other ways to study ASR one would expect to check the samples in this research with those other methodologies, or at least the intention should be indicated in the recommendations for further research.

Best regards,

Author Response

I appreciate the feedback and revisions stated. Please find below a detailed reply to how the comments are addressed:

1. Keywords are revised. The keyword "moisture" is removed as per the reviewer's recommendation.
2. Abstract is shortened. Abstract shortening is attained by removing detailed introduction pertinent to ASR as recommended. Current revised abstract is more brief and concise.
3. Introduction section is revised and shortened by cutting very old information.
4. The number of pictures is reduced as recommended. Citations are added to figures and tables captions.
5. Silica Fume and Type C fly ash were used due to their availability in local market and due to the fact that they are currently standardized in the DOT mix design. A statement was added to explain this within the manuscript. Also, the selected fine sand samples are from river origin (also added to the manuscript).
6. The possibility of using additional methods for ASR assessment is listed in the manuscript as advised. The Recommendations for Future Research section is rewritten.

Round 2

Reviewer 1 Report

The reviewer's comments were taken into account, the work was corrected.

Reviewer 2 Report

The article has been corrected as requested.