Curing Stress Influences the Mechanical Characteristics of Cemented Paste Backfill and Its Damage Constitutive Model
Round 1
Reviewer 1 Report
The manuscript can be accepted after this minor revision.
It is recommended authors differentiate the research gap and novelty of the present study.
Author Response
Authors’ reply to the Editor’s and Reviewers’ questions/comments/suggestions
The authors would like to greatly appreciate the valuable, constructive and encouraging comments, suggestions and contributions of the Editor and Reviewer to improve the quality of their original research paper. All the points highlighted by editor and reviewer have been fully addressed and clarified. We have completely revised the paper and hope that it meets with your and reviewer’ approval. Please find below our responses to the Editor’s and Reviewer’ comments/questions/suggestions:
(Authors’ reply: Blue in color)
Editor’s Summary
Your manuscript has now been reviewed by experts in the field. Please find your manuscript with the referee reports at this link. Please revise the manuscript according to the referees' comments and upload the revised file within 10 days.
Authors: We would like to thank you very much for giving us the opportunity to reply, we have read with great interest the pertinent comments made by you and two anonymous reviewers. After carefully thinking about their and your suggestions, our main modifications are as follows:
Reviewer #1:
The manuscript can be accepted after this minor revision.
Authors: We are grateful to the reviewer for his/her meticulous reading of our paper. The review is detailed and helpful to finalize our paper. We kindly acknowledge his/her constructive review.
It is recommended authors differentiate the research gap and novelty of the present study.
Authors: Thank you for your valuable comment. The review’s suggestions is right, this paper is mainly to study the curing stress influences the mechanical characteristics of cemented paste backfill and its damage constitutive model, according to the introduction, many references have been shown about the mechanical properties and its damage constitutive model of the CPB, while the study has seldom considered the mechanical characteristics and damage constitutive model under the influence of curing stress, especially the two-stage constitutive damage model of the CPB specimens.
Sincerely yours,
Dr. Shunman Chen
On behalf of the co-authors
Author Response File: 
Author Response.docx
Reviewer 2 Report
Respected Authors
The study presents a well composed research program and touches a very important issue related to curing stress influence on the mechanical characteristics of cemented paste backfill. The introductory part is well referenced. However, I was slightly disappointed that you’ve found mainly Chinese articles for your reference list (70%). I understand the ease to collect "local" sources, however, the problem is of global importance and widening of the reference list always attracts attention and raises the citing potential of the study, The format of references in the body text and in the reference list is not fully in accordance with MDPI template. Concerning references again, I appreciate that you avoided cluster citations in the introductory part and every cited paper is properly introduced to the Reader in order to prove their relevance and importance for the current study.
I appreciate the research part of your study. I have, however, an impression that the time that you devoted for curing of your samples was too short. It is not frequent indeed to see the testing of samples that are older than standard 28 days, but it seems to be reasonable for non-standard engineered cementitious composites that may require a longer time to reach the final strength or, unfortunately, a decrease of strength and stiffness is observed in a longer period. Such procedure (longer time of curing) was applied in work DOI: 10.1088/1757-899X/365/3/032049, where the compressive strength evolution in soil cement samples with fly-ash admixtures was studied for various cement - fly ash proportions. Also, in the work DOI: 10.3390/ma15103689, a 3-month period of curing was applied to study the evaluation of material strength in the case of activated composite used for cemented backfill in mining industry.
Presented study focusses on strength of the composite and creating a constitutive model that would describe well the behavior of CPB material in compressive testing, depending on the curing stress. I know that in course of uniaxial compressive test it is possible evaluate elastic modulus if only both: stresses and strains are maintained (e.g., your Figure 6, 7, 8). I miss a little the more precise description of your testing methodology. Maybe it's in accordance with some standards described in references [28-31] that are not clearly described. Anyway, a more precise description of sample preparation, curing conditions, testing methodology (speed of loading). I have an impression that just with a little effort you could present results of E modulus evaluation for your tested samples and present the results in strength-stiffness coordinates. this relationship is usually linear for a defined curing stress. I could recommend you, a paper 10.1088/1757-899X/245/2/022019 with a nice description of these issues for the deep soil mixing composite (with curing stress = 0).
I appreciate a lot a fact that you do not overestimate the importance of your results. Anyway, please develop, if possible, your conclusions, presenting your results in the light of other researchers’ findings and introduce some reservations concerning direct applicability of your findings to the real-life applications. Please address some issues that you still find attractive for future developments of your current studies.
Please check again spelling, grammar and style in English.
Sincerely.
Author Response
Authors’ reply to the Editor’s and Reviewers’ questions/comments/suggestions
The authors would like to greatly appreciate the valuable, constructive and encouraging comments, suggestions and contributions of the Editor and Reviewer to improve the quality of their original research paper. All the points highlighted by editor and reviewer have been fully addressed and clarified. We have completely revised the paper and hope that it meets with your and reviewer’ approval. Please find below our responses to the Editor’s and Reviewer’ comments/questions/suggestions:
(Authors’ reply: Blue in color)
Editor’s Summary
Your manuscript has now been reviewed by experts in the field. Please find your manuscript with the referee reports at this link. Please revise the manuscript according to the referees' comments and upload the revised file within 10 days.
Authors: We would like to thank you very much for giving us the opportunity to reply, we have read with great interest the pertinent comments made by you and two anonymous reviewers. After carefully thinking about their and your suggestions, our main modifications are as follows:
Reviewer #2:
1）The study presents a well composed research program and touches a very important issue related to curing stress influence on the mechanical characteristics of cemented paste backfill. The introductory part is well referenced. However, I was slightly disappointed that you’ve found mainly Chinese articles for your reference list (70%). I understand the ease to collect "local" sources, however, the problem is of global importance and widening of the reference list always attracts attention and raises the citing potential of the study, The format of references in the body text and in the reference list is not fully in accordance with MDPI template. Concerning references again, I appreciate that you avoided cluster citations in the introductory part and every cited paper is properly introduced to the Reader in order to prove their relevance and importance for the current study.
Authors: Thank you for your kind suggestion. Some references have been revised for new references, such as [12], [21], [37] and [43]. In fact, most of the references are published on the foreign journal, such as construction and building materials, power technology and science of total environment, and many of the scholars are from China. In addition, I think the comments by the review’s is really very helpful, I will pay more attention on it in the future work, also the review point out that the format of references in the body text and in the reference list is not fully in accordance with MDPI template, all of them have been revised according to the comments, which are shown on the revised manuscript.
[12] Shi X.L., Wang X.L., Wang X.L.. Dual waste utilization in cemented paste backfill using steel slag and mine tailings and the heavy metals immobilization effects. Powder Technol. 2022, 403,117413. https://doi.org/10.1016/j.powtec.2022.117413.
[21] Qi, C.C., Chen, Q.S., Fourie, A., Tang, X.L., Zhang, Q.L., Dong, X.J., Feng Y.. Constitutive modelling of cemented paste backfill: a data-mining approach. Constr. Build. Mater. 2019,197, 262-270. https://doi.org/10.1016/j.conbuildmat.2018.11.142.
[37] Chen Q.S., Zhu L.M., Wang Y.M., Chen J., Qi C.C.. The carbon uptake and mechanical property of cemented paste backfill carbonation curing for low concentration of CO2. Sci. Total Environ. 2022,852,158516. https://doi.org/10.1016/j.scitotenv.2022.158516.
[43] Rade V., Nenad D, Agata G, Gareth A.T., Kevin H.. Constitutive model for fibre reinforced composites with progressive damage based on the spectral decomposition of material stiffness tensor. Compos. Struct. 2022, 292, 115596. https://doi.org/10.1016/j.compstruct.2022.115596.
2）I appreciate the research part of your study. I have, however, an impression that the time that you devoted for curing of your samples was too short. It is not frequent indeed to see the testing of samples that are older than standard 28 days, but it seems to be reasonable for non-standard engineered cementitious composites that may require a longer time to reach the final strength or, unfortunately, a decrease of strength and stiffness is observed in a longer period. Such procedure (longer time of curing) was applied in work DOI: 10.1088/1757-899X/365/3/032049, where the compressive strength evolution in soil cement samples with fly-ash admixtures was studied for various cement - fly ash proportions. Also, in the work DOI: 10.3390/ma15103689, a 3-month period of curing was applied to study the evaluation of material strength in the case of activated composite used for cemented backfill in mining industry.
Authors: Thank you for your valuable comments. The authors have made the following explanations in the revised paper.
Your evaluable comments are really very helpful, in this paper, the UCS of 3, 7, 14 and 28 days for the CPB specimens are considered, because the UCS of the CPB cured for 28 days is only selected as the standard to design the mix proportion of the CPB, therefore, the samples that are older than standard 28 days are not considered, but the comments by the review is really helpful. In the future work, the mechanical properties of the CPB specimens that are older than standard 28 days will be deeply studied.
3）Presented study focusses on strength of the composite and creating a constitutive model that would describe well the behavior of CPB material in compressive testing, depending on the curing stress. I know that in course of uniaxial compressive test it is possible evaluate elastic modulus if only both: stresses and strains are maintained (e.g., your Figure 6, 7, 8). I miss a little the more precise description of your testing methodology. Maybe it's in accordance with some standards described in references [28-31] that are not clearly described. Anyway, a more precise description of sample preparation, curing conditions, testing methodology (speed of loading). I have an impression that just with a little effort you could present results of E modulus evaluation for your tested samples and present the results in strength-stiffness coordinates. this relationship is usually linear for a defined curing stress. I could recommend you, a paper 10.1088/1757-899X/245/2/022019 with a nice description of these issues for the deep soil mixing composite (with curing stress = 0).
Authors: Thank you for this suggestion. In the revised manuscript.
2.2.2 Uniaxial compressive equipment：According to the studies by Egorova [38], when the specimens are cured for 3, 7, 14 and 38 days, they are making to the standard specimens with diameter 50 mm and length of 100 mm, then the specimens are placed on the WDW-50 servo-controlled uniaxial compression testing experiment, the loading rate is 0.1 mm/m, then the UCS is determined by the average value of three specimens with the same condition.
[38] Egorova, A., Rybak, J., Stefaniuk, D., Przemysław Zajączkowski.. Basic aspects of deep soil mixing technology control. Iop Conference, 2017,245(2), 022019.
2.3 Schemes of the experiment ：then they are cured for 3 days, in addition, the specimens are placed on the curing box with the standard curing conditions (with curing temperature of 20 ± 2 °C and humidity of 95 ±1 % ) until they are cured for 7, 14 and 28 days.
Moreover, E modulus is easy to obtained according to the references of the [38], and I think it is easy, therefore, the E modulus is not presented in this manuscript, and I will analyze it in the future work, thank you.
4）I appreciate a lot a fact that you do not overestimate the importance of your results. Anyway, please develop, if possible, your conclusions, presenting your results in the light of other researchers’ findings and introduce some reservations concerning direct applicability of your findings to the real-life applications. Please address some issues that you still find attractive for future developments of your current studies.
Authors: Thank you for this suggestion. The authors agree to revise the manuscript, which is shown as followed:
According to the studies above, it can be found that the curing stress is beneficial to the improve of the UCS for the CPB specimens, and the two stage damage constitutive model is also established, while there are also more deeper works needed to do, such as the considering of more influencing factor, and the cement to tailing ratio, mass concentration and cement type may be considered, in addition, it is also needed to extend our work to the field application. More research work is to done about the CPB characteristics in the future.
5）Please check again spelling, grammar and style in English.
Authors: Thank you for this suggestion. The authors have checked the spelling, grammer and style in English thoroughly.
Sincerely yours,
Dr. Shunman Chen
On behalf of the co-authors
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Dear Dr. Shunman Chen and Respected co-Authors
I'm truly satisfied with your responses and especially with the improvements that you introduced to your manuscript.
I believe that your study may be published "as it is now".
However, please bear in mind, concerning your future studies, that in scientific research we have to balance two directions: accepting and using the standard methodology and develop (widen, discover, look for) new frontiers and new horizons. As long as you stick to standard procedures of sample treatment (curing) limited to 28 days, you just comply to the well-known rules. Your work is absolutely correct and worth to be published. But it is not breakthrough research. The same comment applies to neglecting the presentation of elastic modulus for tested samples. Yes indeed, a cautious Reader may derive it on the basis of presented stress-strain curves. Personally, I'd appreciate some comments on it, as the material stiffness may be a ruling factor in numerical studies. Anyway, you have a nice set of data for future publications :-)
Sincerely
