Alkali-Activated Brick Aggregates as Industrial Valorized Wastes: Synthesis and Properties

Round 1

Reviewer 1 Report

It seems that the originality and the relevance are acceptable in the field. It helps to develop a new direction in the application of geopolymer. So far, it is not very common to find the NMR results of rich geopolymer in published materials. The authors need to clarify whether the NMR results are appropriate to analyze the Geopolymer.

The authors discussed the NMR results in detail; however, before the analysis of the NMR results, the authors should have presented the content of the iron element, due to the iron content will significantly affect the NMR spectra. If this point can not stand, all of the analysis is questionable.

The English of this manuscript is acceptable. 

Author Response

Villeneuve d’Ascq (France), August 2nd 2023

To Reviewer 1

Dear Madam or Sir,

We have revised the manuscript according Reviewers’ recommendations and suggestions. 

We have made the following corrections and modifications (the added text is typed in red).

(1)   Comments (with a new reference cited in the text) about the importance of the RMR technique for the analysis of complex (three-dimensional) geo-polymeric gels generated from industrial by-products ( slag and fly ash), have been made in the version., see paragraph 3.3..

(2) “Before undertaking the analysis of NMR data it was important to mention that it was observed no noticeable broadenings of NMR peaks related to paramagnetic NMR effects arising from the interactions of nuclear spins (1H, 23Na, 29Si or 27Al atoms) with unpaired d electrons (Fe(III). This could result from the presence of too low Fe contents detected in alkali-brick samples by ESEM/EDS (ranging from 0.2% to 0.7%), suggesting that resonating nuclei detected were certainly located far from paramagnetic centers”. 

This comment has been added to the text in paragraph 3.3.

We gratefully thank you for helping us to improve significantly the scientific content of this manuscript.

Best regards

Dr. A. Boughriet

Reviewer 2 Report

This study focuses on the investigation of employing industrial by-products as solid precursors for the synthesis of alkali-activated binders and as alternative to Portland cement for immobilization of hazardous, toxic and nuclear wastes, which is interesting and meaningful, but there are some experiments should be added to improve the completeness of the manuscript.

（1）        XRD patterns should be supplied to confirm the crystal structure of the raw material, the resultant geopolymer, and especially the zeolite phase in the matrix.

（2）        The influence of immobilized cations on the structure of geopolymer should be discussed.

（3）        Leaching experiments with detailed data should be conducted to confirm the ions immobilization efficiency of geopolymer.

（4）        XPS analysis is suggested to be supplied to confirm the state of the immobilized cations.

（5）        Py-FTIR is suggested to be supplied to analyze the difference between Na and H form geopolymer.

The Quality of English Languag is good.

Author Response

Villeneuve d’Ascq (France), August 2nd 2023

To Reviewer 2

Dear Madam or Sir,

We have revised the manuscript according Reviewers’ recommendations and suggestions.

We have made the following corrections and modifications (the added text is typed in red).

• XRD patterns of raw brick and alkal-brick are now given in this new version.
• Paragraph 3.4. entitled “Aqueous structural stability and cationic immobilization characteristics” has been added in the text.
• Studies are under way for evaluating the state of the immobilized radio-elements and their degree of encapsulation inside composite frameworks after calcination at different temperatures. For that, X-ray photoelectron spectroscopy (XPS) should be useful for etching matrix surfaces by ionic Ar+ bombardment at different durations and analysing surface elements versus formed-crater depth. This comment has been added in section 5 “Future propects”.
• Pyrolysis-Fourier transform infrared (Py-FTIR) spectrometric studies of alkali-brick at elevated temperatures are in prospect for understanding the pyrolysates composition and their evolution over time and analyzing the difference between Na and H form geo-polymer. This comment has been added in section 5 “Future propects”.

We gratefully thank you for helping us to improve significantly the scientific content of this manuscript.

Best regards

Dr. A. Boughriet

Reviewer 3 Report

In today's world, a great deal of attention is being focused on the issues of recycling, greenhouse gas emissions, industrial waste management, and broader ecology. Due to the challenges associated with radioactive waste disposal and its high costs, the topic addressed in the publication, which explores the possibility of incorporating hazardous substances into geopolymer matrices, is highly desirable.

The authors have approached the analysis of materials with due diligence, and the results presented in the publication offer a real opportunity to partially solve the problems related to managing some radioactive materials. The authors point out further research directions in the publication, which should build upon the research presented in the above-reviewed publication. I hope that future publications by the authors will confirm this thesis, and that the presented research will find its application in industries involved in waste management and disposal.

Of course, the authors have not avoided minor editorial errors:

•             The unit and the value should be on the same line (335, 348, 366).

•             There should be no single letters at the end of lines (418, 465, 506).

•             Figures should be centered.

The topic of the publication corresponds to its content, and the scope of the research was correctly planned. The analysis of the presented results is accurate, and the references included in the article is sufficient. The language used in the publication is correct.

The article bears the characteristics of a scientific publication, which makes it suitable for publication in the journal "Ceramics." After making minor corrections, I recommend that the article be published in the journal "Ceramics."

Author Response

Villeneuve d’Ascq (France), August 2nd 2023

To Reviewer 3

Dear Madam or Sir,

We have revised the manuscript according Reviewers’ recommendations and suggestions.

We have made the following corrections and modifications (the added text is typed in red).

• The unit and the value are now on the same line.
• Single letters at the end of lines are suppressed at best.
• All Figures and Tables are now centered in the new version.

We gratefully thank you for helping us to improve significantly the scientific content of this manuscript.

Best regards

Dr. A. Boughriet

Reviewer 4 Report

The paper is interesting and important. Some comments can be found below:

-We live now in a climate emergency so its most strange that the authors have not start the paper by mentioning exactly that. It seems that they are not aware about the words of a Professor of Physics at the University of Oxford authored a paper where one can read the following:

 “Let’s get this on the table right away, without mincing words. With regard to the climate crisis, yes, it’s time to panic”

Pierrehumbert, R., 2019. There is no Plan B for dealing with the climate crisis. Bulletin of the Atomic Scientists, pp.1-7.

So please start the introduction by draw a connection between environmental degradation and resource efficiency.

-The paper is interesting but has some conflicting statements. In the abstract the authors wrote that “Improving the quality of the RCAs by an advanced and cost-effective treatment is an important step to overcome the drawbacks of their use in construction industry”. But then they go and use a nano particle that has a high cost. And in the conclusions they wrote that “which can decrease the cost of treated RCA concretes” without any evidence to supoport that !

Author Response

Villeneuve d’Ascq (France), August 2nd 2023

To Reviewer 4

Dear Madam or Sir,

We have revised the manuscript according Reviewers’ recommendations and suggestions.

We have made the following corrections and modifications (the added text is typed in red).

• At the beginning of the Introduction, the authors made some comments about connections between environmental degradation and resource efficiency. The paper published by Pierrehumbert (2019) “ There is no Plan B for dealing with the climate crisis. Bulletin of the Atomic Scientists, pp.1-7 ”, is cited in the new version.
• Some comments about the making cost of the synthesized composite have been made in Materials and Methods Note that in this section the paragraph entitled “2.1. Materials preparation“, becomes “2.1. Materials preparation and making cost”.

We gratefully thank you for helping us to improve significantly the scientific content of this manuscript.

Best regards

Dr. A. Boughriet

Round 2

Reviewer 2 Report

This maunscript can be accepted as it is!

Reviewer 4 Report

The revised paper can be accepted