Sustainable Utilization of Waste Pumice Powder in Slag-Based Geopolymer Concretes: Fresh and Mechanical Properties
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe paper is on utilization of waste pumice in Geopolymer Concretes. The considerable and systematic experimental work was conducted. Remarks and comments are added to the PDF copy of manuscript using review tools.
It was shown that the addition of waste pumice deteriorates key properties of geopolymer concrete. However, it was stated that the material containing up to 70 % pumice is still applicable for concrete structural application. Therefore, it would be essential to mention potential application of this material. It was also shown that curing at 60 oC can improve properties. What would be the situation where heat treatment at 60 oC can be applied during construction material fabrication?
The main drawback of the manuscript refers to the conclusions which are not supported by experimental findings. Namely, the conclusions are supported by literature data. It is also unacceptable to make construction material without microstructural analysis. It would be essential to present optical or SEM images to support conclusions. It is especially important when it comes to the mechanical properties which are strongly affected by density as well as microstructure.
The recommendation is: Reconsider after major revisions
Comments for author File: 
Comments.pdf
Minor editing.
Author Response
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Reviewer 2 Report
Comments and Suggestions for AuthorsIn this study, the feasibility of using waste pumice powder as an alternative to granular blast furnace slag as a binder to produce geopolymer concrete was investigated. Three sets of geopolymer concrete mixes were developed with three ratios of alkaline activator/binder of 0.45, 0.5, and 0.55. Eight geopolymer concrete mixes were prepared for each set with eight replacement ratios of GGBFS with waste pumice powder. The influence of waste pumice powder addition as a substitute source of aluminosilicate precursors on the fresh, mechanical, and physical characteristics of waste pumice powder/slag-based geopolymer were studied.
In this paper, the research of construction waste as precursor materials of geopolymers has certain engineering application value.
1. The research objectives should be clearly stated in the abstract and it should be clear whether these objectives have been achieved.
2. In the introduction, there is insufficient discussion and quotation of WPP. Since this paper mainly studies the effect of WPP on GC performance, it is recommended to add this part and discuss it.
3. In the introduction, the discussion of existing research is slightly insufficient, and the review of existing relevant research should be enriched. At the same time, it should be compared with the existing literature research in the same field to highlight the novelty of this manuscript.
4. In the introduction, on page 3, line 100, the abbreviation "WPP" should first list the full name.
5. The terminology and abbreviations in the manuscript need to be clearer to ensure the reader's understanding.
6. In Table 2 of the manuscript, "Pumice" and "Slag" are used instead of "WPP" and "GGBFS". It is recommended to use a unified format for presentation.
7. In Table 2 of the manuscript, Binder includes Pumice and Slag. In general, in the composition of geopolymers, binders include a precursor and alkaline activator. From the point of view of this paper, it seems more accurate to define Pumice and Slag as precursors.
8. Figure 3 shows the Effect of A/B ratio and replacement ratio of WPP with GGBFS on setting-time of geopolymer concrete. “geopolymer concrete” should be replaced by “GC”. Similar problems need to be adjusted.
9. In Figure 3 of the paper, the three figures should be annotated with (a), (b), and (c) respectively.
10. The conclusion should be further improved to increase the prospect and practical application value of the research results in engineering applications.
Comments on the Quality of English Language
Minor editing of English language required.
Author Response
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Reviewer 3 Report
Comments and Suggestions for AuthorsThe paper presents a “Sustainable Utilization of Waste Pumice Powder in Slag-Based Geopolymer Concretes: Fresh and Mechanical Properties.” The present study deals with using pumice waste from demolishing light-weight pumice blocks in slag-based geopolymers. This investigation examines the strength and physical properties of GC, specifically focusing on the influence of utilizing such waste on workability. The study’s main purpose is to examine the mechanical and fresh properties of waste-based GC that had been demolished during construction, with different WPP contents, A/B ratios, and curing regimes. The paper subject is interesting and required minor revision as follows:
· Figures 1 and 2 need more clarity for better understanding and require setting the image size.
· Organize the page alignment, especially for figures and tables.
· Add the standard specifications of the absorption and density tests.
· The ultrasonic pulse velocity (UPV) test wasn’t stated in the abstract section. Revise that.
· All the x-axis details in the results figures need to be revised.
· It is very important to provide microstructure analysis for a better understanding of the internal activation of the geopolymer paste.
· The waste pumice powder includes the same element ratios (SiO2, Al2O3, Fe2O3, and CaO) nearest the element’s rations in the granulated blast furnace slag. Provide more discussion, and the main reason for the highest reduction in the compressive strength results when increasing the WPP ratio.
Author Response
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Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe comment are responded.
Author Response
The author would like to thank the reviewer.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors have responded to most of our comments, but the mixes in the x-axis of all result figures are still not correct.
Author Response
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Author Response File: Author Response.pdf
Round 3
Reviewer 3 Report
Comments and Suggestions for AuthorsIt is unreasonable for third revesion process, the authors stated that in the abstract section "The replacement ratios of GGBFS with WPP (0%, 10%, 20%, 30%, 40%,50%,70%, and 100%)".
This ratios inconsistent with the replacement ratios in the experimental program and results.
Author Response
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Author Response File: Author Response.pdf
