Clay as a Sustainable Binder for Concrete—A Review

Round 1

Reviewer 1 Report

Comments to manuscript: “Clay as a sustainable binder for concrete - A review”

Manuscript ID: constrmater-1255530-peer-review-v1

Authors: Seyed Sina Mousavi 1*, Chandrasekhar Bhojaraju 2, and Claudiane Ouellet-Plamondon

The authors consider several types of clay as possible sustainable binders. They comment that the impact of clay as a cement substitute depends on the dosage and treatment methods. The authors review studies on the effects of different types of clay, including raw, calcined, modified and nano on the fundamental properties of fresh and hardened concrete.

General comments:

The work is interesting as reference material, but it does not provide any novelty, as the field of clays and clay minerals is currently very well studied.

The authors' review is based on somewhat older literature. Similar work has been published recently. It is recommended to look for bibliographies from the last four or five years.

The authors make serious mistakes in their concepts. They consider zeolites and volcanic tuffs as clays. Zeolites are tectosilicates, tuffs are rocks and clays are phyllosilicates. Despite this, neither zeolites nor volcanic tuffs are mentioned in the Abstract, Introduction or Conclusions.

The authors do not clearly explain the usefulness of the work or how the results can be used in the future.

Specific comments:

Abstract: The Abstract does not explain the main objective of the paper or what will be its practical application.

Bibliography: the work is supported by an extensive bibliography, but it tends to be somewhat outdated. There are many up-to-date publications that can be consulted in Open Access.

Line 26: Citation [213] does not follow a logical consecutive order. It should not appear here.

Line 104: Citation [217] does not follow a logical consecutive order. It should not appear here.

Line 110: Figure 1. Put the reference

Line 113: Quartz and feldspars are not impurities in clays, they are precursor minerals.

Line 115: The authors say: "These impurities significantly affect clay characteristics" Explain how these impurities affect the clays.

Line 133: It is completely wrong to consider zeolite as a clay. Zeolites are tectosilicates; clays are phyllosilicates.

Lines 136-138: It is completely wrong to consider zeolite and volcanic tuffs as clays. It is also not true that both zeolites and tuffs have a low level of use.

Line 148: Figure 3. Put reference.

Figure 3: Remove zeolite and volcanic tuff from the graph.

Figure 4: Remove zeolite and volcanic tuff from the graph.

Line 149: Figure 4: Put reference.

Line 177: Table 1. Remove zeolite and volcanic tuff from the table.

Table 1: The LOI value is very low in zeolite... What type of zeolite is...?

Line 184: "The major constituents of zeolites are SiO2, Al2O3, and Fe2O3...". Not completely true... Na2O, K2O, MgO, CaO and H2O should also be considered. Please complete.

Line 185: Reference is made to Table 2, this must be an error. The authors should refer to Table 1 instead. Fix.

Lines 181 to 195: The origin of zeolites, bentonites and other materials is not explained... Why?

Line 246: What are the impurities in clays?

Line 415: Table 3. This table is insignificant, there is a Section dedicated to references. A table with the uses and applications of clays would be more meaningful.

Line 493: The references used tend to be a bit old. There are many recently published works that explain well the effect of clays on the compressive strength of mortars, concretes and cements.

Lines 493 to 494: Replace the word "replacement" by "addition".

Line 496: Replace the word "replacement" by "addition".

Lines 490 to 502: The discussion on the role of zeolite in compressive strength is poor. Zeolites have an extensive literature. This paragraph should be rewritten.

Lines 502 to 509: The authors talk about the efficiency of different types of clays (Figure 15), when they are really talking about the effect of zeolites on mechanical strengths... Do the authors consider zeolites as clays...? This paragraph should be placed in another place.

Line 711: Conclusions. The conclusion is very poor, despite being a very extensive work. It should be rewritten.

Author Response

Please find the attached file as a response to reviewer 1.

Author Response File: Author Response.docx

Reviewer 2 Report

Paper presents an interesting review of clay usage as a binder for concrete. The description of the methodology is well structured in conceptual terms. Paper explains the existing knowledge on a topic based on the published research available and authors.

According to the reviewer opinion paper should be improved by critically analyze the information gathered by identifying gaps in current knowledge; by showing limitations of fresh, hardened, and durability properties of concrete with clay binder; and by formulating areas for further research, reviewing areas of controversy, and reviewing areas of controversy.

Conclusions in the manuscript were related facts substantiated by this review. The English language used throughout the manuscript is good.

Author Response

Please find the attached file as a response to reviewer 2.

Author Response File: Author Response.docx

Reviewer 3 Report

Generally, the contribution covers a very important topic. Some comments are included in the attached pdf-file.

Please allow some general comments:

• The title of the contribution is to my mind misleading. I expected a a review on papers where really considerable amount of portland cement as binder were replaced by clay (in general). Most of the research presented deals with studies where clay is more or less used in small percentages (1% to 5%) ecept for Metakaolin where higher percentages were used.
  For me it is not "clay as binder" but effects of clay as modification of concrete/mortar.
• Still the research is very comprehensive and especially table 3 and the corresponding discussion is very interesting to get an idea, which properties have been tested so far. This table justifies a publication.
• Concerning durability aspects it gets a little "random" from a readers point of view. In this section. There are some single properties presented often only for one type of clay.
  In this section I miss the generalization of effects of clay. And again the mass-percentage which is used in many studies is very limited. In this section I suggest to point out more clearly that general knowledge is still very limited.

 

Comments for author File: Comments.pdf

Author Response

Please find the attached file as a response to reviewer 3.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors have visibly modified the entire manuscript in accordance with the reviewer's initial comments. However, minor revisions are required as indicated below:

- If the working tool used by the authors is the "Scientific Databases Used", then it has to be mentioned in the Abstract. Review

- Figure 1. Put reference at the bottom of the figure in the caption. Review

- Figure 3: Requires bibliographic citation in the caption. Review.

- Figure 4. Requires bibliographic citation in the caption. Review.

- Figure 14. Requires bibliographic citation in the caption. Review.

Once these changes have been made, the work could be proposed for publication.

Author Response

Please find the attached file as a response to the reviewer.

Author Response File: Author Response.docx