Study on the Hydration and Microstructure of B and B/Na Ion-Doped Natural Hydraulic Lime Composed with Silica Fume/Fly Ash

Round 1

Reviewer 1 Report

The study is extensive, easy to follow and relevant to the scope of the journal; however,  the following amendments/further explanations are necessary for the manuscript to improve.

1. The novelty of the article needs to be improved. It should be clearly stated which gap in the literature it fills.

2. What is exactly the research novelty and its necessity for environmental engineering field area?

3. There is no pictures from your lab work process (materials, materials preparation, instruments, etc.). Please add some pictures.

4. There is no appropriate discussion in sections 3.2, 3.4 and 3.7. Please add some more recent studies in this sections and compare your results with similar studies.

5. Figures 2 and 8 have poor quality and are not readable.

 

 

Author Response

 

Comments and Suggestions for Authors

The study is extensive, easy to follow and relevant to the scope of the journal; however,  the following amendments/further explanations are necessary for the manuscript to improve.

 

1. The novelty of the article needs to be improved. It should be clearly stated which gap in the literature it fills.

Ion doping and SCMs are commonly used to modify the performance of NHL. In this paper, the two are coupled to improve the performance of NHL, combining theory with practical application. This is a more likely way to apply NHL. In this study, the first preparation with high hydration activity α- C2SThe lime based cementitious material with excellent performance was prepared by adding FA and SF into the NHL. At the same time, the performance and hydration mechanism of the cementitious material mixed with NHL system were explored, which has guiding significance for the regional application of NHL.

2. What is exactly the research novelty and its necessity for the environmental engineering field area?

NHL is considered to be an eco-friendly construction material due to its lower calcined temperature and characteristic of adsorbing CO₂ in the air. Meanwhile, it is also applicable to more fields except for the restoration of ancient buildings, but its application range is limited by its low mechanical properties in the early stage. Therefore, this paper has conducted in-depth research on NHL doped ions and SCMs and expanded its potential application range by improving its hydration speed and properties.

3. There is no pictures from your lab work process (materials, materials preparation, instruments, etc.). Please add some pictures.

Thank you for your reminder. We have added the NHL preparation process schematic in paper

4. There is no appropriate discussion in sections 3.2, 3.4 and 3.7. Please add some more recent studies in this sections and compare your results with similar studies.

The comparison with the current studies has been added to the discussion section and the discussion has been further adjusted.

5. Figures 2 and 8 have poor quality and are not readable.4

The original figures have been submitted to the editorial department. The document may be compressed when it is sent to the reviewer. I'm sorry that the picture is not clear when reviewing the manuscript. We have increased the size of the picture. I hope that the reviewer can see it as clearly as possible

 

 

Author Response File: Author Response.docx

Reviewer 2 Report

This study is interesting because scientifically it discovers some special questions of belite phase stabilizing in hydraulic lime and its application in complex binders.  Also, the application of these results in materials for repairing and, especially, restoring is very actual in historical objects’ repairing where authentic materials are demanded. So, this manuscript has definite value for publishing. However, there are some questions and suggestions to authors for this paper improving.

1.    Introduction concerned B and B/Na method of C₂S stabilizing, but there are many works with effective stabilizing with Cr-ion and F containing materials, and others, so the B-dope method choosing effectiveness requires some justification.

2.    In methods of lime calcination, the cooling conditions are not described. HL without stabilizers after calcination and analyze does not contain the g-C₂S phase, so we have to suppose that the fast stabilizing cooling was made. If not, the g-C₂S phase absence without chemical stabilizing is not cleared.

3.    Fig.6. The crack photos are too small for analyzing, so the cracking reasons in discussion are not clear too.

4.    Fig. 9 presents that in HL with SCM adding chemically bonded water increases and Ca(OH)₂decreases. But Ca(OH)₂ contains 30% of bonded water and S-C-H gel just about 15%, so the HL’s with FA and S’ bonded water decreasing is waited too. It’s not clear.

5.    In final comparison of binders’ variants it could be very reasonable to present mechanical and self-cracking properties not only in air but in water conditions, and not only for HL but for the binder on the base of Ca(OH)₂ and FA and S for HL’s most effectiveness demonstration.

Comments for author File: Comments.pdf

Author Response

Comments and Suggestions for Authors

This study is interesting because scientifically it discovers some special questions of belite phase stabilizing in hydraulic lime and its application in complex binders.  Also, the application of these results in materials for repairing and, especially, restoring is very actual in historical objects’ repairing where authentic materials are demanded. So, this manuscript has definite value for publishing. However, there are some questions and suggestions to authors for this paper improving.

1. Introduction concerned B and B/Na method of C₂S stabilizing, but there are many works with effective stabilizing with Cr-ion and F containing materials, and others, so the B-dope method choosing effectiveness requires some justification.

This opinion is very meaningful. In fact, the selection range of doped ions is relatively wide, and many elements such as Na, S, P, Cr, F, etc. have stable effects. In addition to being widely used, the selection of B also has certain advantages in economy.

2. In methods of lime calcination, the cooling conditions are not described. HL without stabilizers after calcination and analyze does not contain the g-C₂S phase, so we have to suppose that the fast stabilizing cooling was made. If not, the g-C₂S phase absence without chemical stabilizing is not cleared.

Thanks for your reminder. In this paper, the cooling conditions are cooling with the furnace. Due to the addition of doping ions and the impurity in raw materials. there are almost no γ-C2S in the fabricated NHL. In the Introduction part, we’ve discussed the stabilizing effect of minor ions. At the same time, relevant research shows that when C2S is synthesized with natural raw materials, γ-C2S hardly appears

3. Fig.6. The crack photos are too small for analyzing, so the cracking reasons in discussion are not clear too.

The original figures have been submitted to the editorial department. The document may be compressed when it is sent to the reviewer. I'm sorry that the picture is not clear when reviewing the manuscript. We have increased the size of the picture. I hope that the reviewer can see it as clearly as possible

4. Fig. 9 presents that in HL with SCM adding chemically bonded water increases and Ca(OH)₂decreases. But Ca(OH)₂contains 30% of bonded water and S-C-H gel just about 15%, so the HL’s with FA and S’ bonded water decreasing is waited too. It’s not clear.

Ca(OH)₂ in the samples originates from three aspects: the self-contained calcium hydroxide, the calcium hydroxide produced by C2S hydration, and the secondary calcium hydroxide produced by the pozzolanic reaction of SCMs Meanwhile, the C-S-H gel can be produced by the hydration process of C2S and the pozzolanic reaction of SCMs. Due to the difference in decomposition temperature, the content of each component can be calculated separately. The pozzolanic reaction also consumes Ca(OH)2, thus the content change trend of C-S-H gel and Ca (OH) 2 is not the same.

5. In final comparison of binders’ variants it could be very reasonable to present mechanical and self-cracking properties not only in air but in water conditions, and not only for HL but for the binder on the base of Ca(OH)₂and FA and S for HL’s most effectiveness demonstration.

我们完全同意审稿人的意见。感谢您的宝贵意见。研究不同固化方法下不同类型HL的水化过程，无疑对HL的水化和应用具有重要意义。但是，太大的系统将大大增加实验次数。HL在空气中的固化是一种比较实用的固化方法，因此，在过去的实验中，我们优先选择这种维护方法，并将其他维护方法作为独立的影响因素进行单独探讨。这在本文中没有反映出来。我们将在今后的工作中完善该系统。

 

Round 2

Reviewer 1 Report

All comments were addressed properly.