Recent Advances in Geopolymer Technology. A Potential Eco-Friendly Solution in the Construction Materials Industry: A Review
Round 1
Reviewer 1 Report
In my opinion, the subject of the manuscript is interesting. The authors have conducted a complete use of the review of information regarding recent advances in geopolymer technology. They described in detail in their work a potential eco-friendly solution in the construction materials industry. I am of the view that geopolymer technology is crucial to the industry, as they determine the development and competitiveness of a lot of sectors. Therefore, I believe that this type of review is essential in science. To my mind, geopolymer technology creates the possibility of developing original solutions to protect the environment. The authors describe in the manuscript an overview of noteworthy aspects for future research development such as innovative Geopolymer-based formulations (including alkali-activated blends for Additive Manufacturing and thermo-acoustic insulating cellular compounds), concrete applications successfully scaled in the civil architectural field, and the perspective directions of Geopolymer technology in terms of commercialization and large-scale diffusion. I opine that the review of aspects for future research presented in the article is reliably prepared. Judging by the number of literature references, I claim that the authors refer to many arousing curiosity publications. In their work, they have cited 100 interesting literature items, including only 3 references to the authors' research works (3 auto--citations). From my point of view, in this manuscript, there are appropriate and adequate references to related and previous works described by other scientists. The title fully describes the subject matter of the article. I want to press the point that the authors of the manuscript describe the information, which that may be of use to other researchers when working on Geopolymer technology. To my mind, the figures and tables included in the manuscript are of good quality and require no corrections. The English used in the manuscript is correct.
I am convinced that the paper can be published.
Author Response
The authors would like to thank the reviewer for careful analysis and positive feedback on
the present manuscript
Reviewer 2 Report
Very interesting manuscript, very well written, especially in the first part. I have only few comments and suggestions for possible improvements.
The most controversial for me is the thesis concerning balanced curing conditions. The authors in Figure 13 wrote that "curing regime (room temperature or higher tempretures) produces similar long term strength results". This is a very bold thesis and, in my opinion, is contrary to most geopolymer research. In my opinion, the authors have not provided sufficient evidence for its support. Of course, there are additives accelerating the setting (eg GBFS), but it is difficult to consider that the 35oC temperature used by Chithambaram [49] is room temperature. Similarly, line 179 contains the thesis that "FA-based geopolymer does not require high-temperture processing". I did not find such a thesis in the referenced studies of Kong [23].
In chapter 2.2 can be added the information that the chemical composition depends on the type of coal (anthracite coal vs lignite). Lignite contains much more lime.
Among the minerals that can be used as a precursor (chapter 2.3), mining waste (e.g. waste from tungsten mines - Pacheco-Torgan, Castro-Gomes) can be added.
Line 839 - which means X-printing, Z-printing direction, please orient it to the printing direction (perpendicular, parallel, in the direction of the layer increment).
Conclusions - In my opinion, one of the main limitations for the development of geopolymer use is not only availability of raw materials, but also instability of their chemical composition.
Reference 100 (line 1224) is "empty".
Author Response
Reviewer comment: Very interesting manuscript, very well written, especially in the first
part. I have only few comments and suggestions for possible improvements.
Authors reply: The authors would like to thank the reviewer for the positive feedback and
valuable comments in improving the manuscript
Reviewer comment: The most controversial for me is the thesis concerning balanced curing
conditions. The authors in Figure 13 wrote that "curing regime (room temperature or
higher tempretures) produces similar long term strength results". This is a very bold thesis
and, in my opinion, is contrary to most geopolymer research. In my opinion, the authors
have not provided sufficient evidence for its support. Of course, there are additives
accelerating the setting (eg GBFS), but it is difficult to consider that the 35oC temperature
used by Chithambaram [49] is room temperature. Similarly, line 179 contains the thesis
that "FA-based geopolymer does not require high-temperture processing". I did not find
such a thesis in the referenced studies of Kong [23].
Authors reply: The description about the effect of the curing regime on the mechanical and
structural properties of Geopolymer materials (see Figure 12) has been modified in
accordance with the reviewer's comment. The authors agree with the reviewer's
discussion.
Reviewer comment: In chapter 2.2 can be added the information that the chemical
composition depends on the type of coal (anthracite coal vs lignite). Lignite contains much
more lime.
Authors reply: The authors accepted the reviewer's suggestion by adding in the paper the
relationship between chemical composition and type of coal (see Line 180)
Reviewer comment: Among the minerals that can be used as a precursor (chapter 2.3),
mining waste (e.g. waste from tungsten mines - Pacheco-Torgan, Castro-Gomes) can be
added.
Authors reply: As suggested by the reviewer, mining waste is mentioned as a mineral
precursor (see Line 203). Besides, a brief overview of Pacheco-Torgal et al. research
(Tungsten mining waste) has been added (see Line 246)
Reviewer comment: Line 839 - which means X-printing, Z-printing direction, please orient it
to the printing direction (perpendicular, parallel, in the direction of the layer increment)Authors reply: According to the reviewer's comment, the meaning of the two printing
directions has been added (see Line 858)
Reviewer comment: Conclusions - In my opinion, one of the main limitations for the
development of geopolymer use is not only availability of raw materials, but also
instability of their chemical composition.
Authors reply: The conclusions have been implemented by adding this evidence (see Line
1002)
Reviewer comment: Reference 100 (line 1224) is "empty".
Authors reply: Correct
