Effect of Micro-Silica Addition into Electric Arc Furnace Steel Slag Eco-Efficient Concrete

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The issues are presented in the article: "Effect of micro-silica addition into EAFS eco-efficient concrete" are interesting. This paper focuses on analyzing the performance of replacing natural aggregates by EAFS aggregate and its effect on mechanical properties is analysed. The Authors determined the identify the optimal mix proportions of each aggregate that help to improve the strength of "The eco efficient concrete using EAFS”. This study investigated the compressive and flexural behaviour of EAFS with microsilica additive in concrete.

This manuscript has traditional structure of scientific article. However, the article has some shortcomings. The main shortcoming is that the authors failed to define the novelty/originality of this work. The work is interesting but the innovation points seems inadequate. At this stage, it requires necessary improvements to take introduced.

Comments:

1. I think that the addition of EAFS and fly ash to concrete will also have an effect on highest concentrations of natural radionuclides. EAFS and cements used in the construction industry contain natural radioactive isotopes, such as radium (²²⁶Ra), thorium (²³²Th) and potassium (⁴⁰K), and their specific activity may exceed the average specific activity. You have to comment on that.
2. The Authors notice some variables influencing the measurement process (physical properties of cement, chemical properties of materials, technical specifications of the superplasticizer, properties of aggregates, properties of micro-silica, particle sizes and methodology), but neither describe nor justify the mechanisms behind them. Hence, the paper resembles a simple report, not a research paper, where the conclusions are not only "works" but "how and why". This manuscript should contain better interpretation of obtained results. Must be improved.
3. The Authors should have emphasized on the original contribution and / or innovation derived from this study. I look for originality and innovation; and unfortunately, I see very little.
4. What about the danger in a fire situation? Authors should to comment on that.
5. My main suggestion is to check thoroughly the text, regarding both the language and the information provided. Section "3. Conclusions" is too general and needs to be rewritten. Specific conclusions from the research should be included.
6. The paper can benefit from a minor editorial work up to check up spelling and any grammatical issues.

Author Response

Dear Reviewer,

We greatly appreciate the opportunity you give us to improve the paper with your valuable comments.

To check the changes made in the article, please see the attachment.

Best regards,

The authors

Author Response File: Author Response.pdf

Reviewer 2 Report

After going through the manuscript " Effect of micro-silica addition into EAFS eco-efficient concrete", I would give my comments below.

This paper has an interesting theme, but there are some problems:

- Structure of the introduction of this paper is similar to the technical report, not an academic paper, so authors should again rewrite some of the parts base on journal paper style. More new resources should be used.

- The methodology section is not well organized for the readers to understand the concept.

-Quality of figures 8 is very poor.

Authors can use below references and related works in the field:

- The result of “Hardened properties” is superficial. The authors should try to provide more explanations.

- The language used in the introduction can be more specific to the scope and aim of the study.

Author Response

Dear Reviewer,

We greatly appreciate the opportunity you give us to improve the paper with your valuable comments.

To check the changes made in the article, please see the attachment.

Best regards,

The authors

Author Response File: Author Response.pdf

Reviewer 3 Report

General overview

The paper “applsci-1196244” presents an experimental study regarding the mechanical assessment of several concrete mixes, adopting electric arc furnace slag (EAFS) aggregates in partial and/or total replacement of virgin ones (sand and gravel). Some properties and their variation throughout the different groups are monitored (flexural and compressive strength, density, and consistency).

The topic is compliant with the scope of the journal and well aligned to the special issue “Structural Behaviour of Concrete Waste Materials”.

Unfortunately, in my opinion, the paper presents several major methodological flaws and exposition is diffusely defective. Moreover, the degree of novelty is highly questionable. Several papers and reviews have been published in the last decades discussing similar experimental findings. As an example, the effects of EAFS as recycled aggregates in concrete are assessed in the papers: https://doi.org/10.1016/j.conbuildmat.2012.02.012 and https://doi.org/10.1007/s40831-015-0029-1, dating back to 2012 and 2016, respectively.

The evaluation of the mechanical and physical properties of EAFS (as coarse and fine aggregates) concrete mixtures are also deeply investigated by Manso et al. (2004), as correctly cited by the Authors in [20]. In addition, a vast literature is currently available discussing the effects of micro-silica (silica fume) on the mechanical properties of numerous kinds and formulations of concrete, also with recycled aggregates.

The Authors are warmly invited to stress in a clearer manner the novelty of their work.

The English style and language are quite poor, and sentences are often unclear or mistaken. The manuscript should be rewritten and carefully proofread with the assistance of a mother tongue speaker. In some points, sorry to say that I found difficult to understand the meaning.

The Introductory section should be completely rethought, since it is too generalist and blurred, and the literature background is not adequately illustrated and critically commented. Often, citations appear not to be relevant to the sentence they are referred to (e.g. citations [3,4] in line 36). This section must be clear and schematic, and it is decisive in order to introduce the reader into the topic. As the introduction is now, it is not clear what the Authors are going to present, and the research significance is not addressed at all.

From a scientific standpoint, the most crucial flaw of the paper consists in the lack of a rigorous discussion of the experimental results, which are uncommented and just displayed as in a technical report. Also, some of the results are a bit obvious, like the increment of concrete density when EAFS aggregates are used. The Authors must provide sound arguments to endorse their findings, perform additional tests if necessary to achieve a profound understanding of the processes occurring and influencing the results. Critical comparison with the existing literature is completely missing in the Results section.

The conclusions are therefore scientifically inconsistent and offer a limited value added for the scientific community.

In spite of myself, due to the low degree of novelty, the poor scientific rigour, and the questionable significance of the results reported in this manuscript, I cannot recommend it for possible publication in Applied Sciences. In the list below file some specific remarks are reported, hoping that they may be helpful for the Authors.

Remarks

• The title and the abstract should not contain undisclosed acronyms (EAFS)
• The introduction is blurred and hardly understandable. The Authors should completely rearrange it, taking in appropriate consideration the available results regarding EAFS aggregates and silica fume in concrete, entering the details of the previous findings. As it is now, the section is too generalist, and a broad overview is missing.
• The Authors should devote a paragraph in the introduction highlighting the novelty of the paper and the significance of the results that are going to present. At the moment, this part is missing.
• Line 34: “high impact” is not clear. I usually provide “impact” with a negative sense (e.g. environmental impact). In this case, the use of “impact” is ambiguous.
• Lines 39–48: sorry to say, this paragraph is really confused and wordy, thus it is very tough to understand. It should be completely rearranged for the sake of clarity.
• Line 49: “avoiding this way”: The sentence is unclear. Probably do the Authors mean “avoiding in this way”?
• Line 53: “penetration” of what? Chlorides maybe? Please specify.
• Line 61: “The percentage of its composition” is not a correct phrase.
• Line 71: “the environmental behaviour of the environment” is meaningless and the whole statement should be rewritten because it is hardly understandable.
• Line 76: “slower” seems incorrect. May the Authors intend “lower”?
• Lines 77-78: the sentence “Through the mixing between cement and pozzolan, a mixed cement called pozzolan cement is prepared” is obvious and should be removed.
• Lines 80 and 81: the phrases “concrete performance” and “concrete reliability” are too generic and should be explained. E.g., “Performance” may be intended at the fresh state, short-term, long-term, etc.. And, what do the Authors mean with “concrete reliability”?
• Line 86: amorphous silica (or silicon dioxide), instead of “silicon”
• Line 91: the phrase “decrease the permeability to attention” is meaningless. Please reformulate it.
• Materials and Methods: introductory paragraph (lines 104-108) is redundant and should be removed.
• 2.1.1 (lines 111-122). Data in Table 1 are taken from the technical data sheet (TDS) by the manufacturer, so the ASTM codes should be removed by referring to the TDS available online (https://www.ardestancement.com/home/en/products/portland-cement-type-2). Please drastically slim down this subsection.
• Figure 2: Scale bars must be added to the photos.
• Section 2.2.1: the acronym SSD has not been disclosed.
• Line 237: flexural specimens are not “cubic”, but prismatic.
• All the details about the protocols for mechanical testing must be reported in the Materials and Methods Text at lines 280-292 (compression test) and 327-336 (flexural tests) are misplaced and therefore must be removed, and essential information reported in the relevant section.
• MAIN ISSUE: Result section: results are presented without any comments, any critical comparisons with the existing literature. No arguments or hypotheses have been formulated to endorse and justify the experimental evidence. I cannot even confute the results, because a thorough and rigorous discussion of experimental evidence is missing. Discussion and critical comparisons are essential in a scientific research paper, possibly conducting adequate characterisation tests (e.g. microscopy images of cracked samples). Also, how fitting curves in Fig. 7, 8, 9, 11 and 12 are determined?

Author Response

Dear Reviewer,

We greatly appreciate the opportunity you give us to improve the paper with your valuable comments.

To check the changes made in the article, please see the attachment.

Best regards,

The authors

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Reviewer appreciates the efforts to revise the manuscript. The Authors supplemented the results (partly expanded the introduction section, the discussion of the results and improved the section "3. Conclusions”).

In my opinion, the experimental study are still a preliminary research. The Authors have pointed that the original contribution and / or innovation derived from this study were: "The main original contribution of this research on the behaviour of different percentages of coarse grain and fine grain EAFS slags with different percentages of micro-silica was in determining the effect on compressive and flexural strength of concrete". I look for originality and innovation; and unfortunately, I see little.

The Authors notice some variables influencing the measurement process, but the innovation points seems still inadequate.

I suggest the Authors to carry out more comprehensive and critical literature review on the topic of research (e.g. an effect on highest concentrations of natural radionuclides: doi:10.3390/ma13122824 and about the danger in a fire situation: doi:10.3846/jcem.2018.457). The mentioned references should added in the revised manuscript.

Author Response

Dear Reviewer,

We greatly appreciate the opportunity you give us to improve the paper with your valuable comments. Here you can find the detailed comments and performed changes. You can find the applied changes in the attachment file. Please see the attachment.

 

Best regards,

The authors

Author Response File: Author Response.docx

Reviewer 2 Report

The novelty of this work is the main problem. and also the manuscript needs material characterization analyzes such as SEM, TEM, EDX to investigate materials in micro-scale.

Author Response

Dear Reviewer,

We greatly appreciate the opportunity you give us to improve the paper with your valuable comments. Here you can find the detailed comments and performed changes. You can find the applied changes in the attachment file. Please see the attachment.

 

Best regards,

The authors

Author Response File: Author Response.docx

Reviewer 3 Report

This reviewer is grateful to the Authors for their reply, and for having addressed some of the remarks. The Introduction is now more comprehensive, and the testing protocols are adequately described. However, as detailed below, the discussion is still weak and must be deeply improved to meet the scientific standards of Applied Sciences international journal.

1. In general, the quality of the language is not improved substantially, and several points remain confused and some mistakes still appear (e.g. Line 355: “Figure 11 show”).
2. The title should not have the acronym EAFS alone, and in the abstract, the acronym should be defined once for all, at its first occurrence.
3. Unfortunately, sentence in lines 63-65 is still incorrect. Please revise it thoroughly
4. Unfortunately, sentence in lines 84-85 is incorrect. Please reformulate it.
5. An appropriate reference to the technical data sheet of the cement should be explicitly given in the bibliography. Ref. no. [22] is incomplete and should provide the link to the website.
6. Lines 230-231: The sentence seems incorrect: "According to Standard ASTM C78 Test Method for Flexural Strength of Concrete [37], and beam dimensions of 350 * 100 * 100 mm were selected"
7. Lines 346-349 + Fig.10: Redundant paragraph and image: the testing protocol is already described in line 230 and following. Please remove and, optionally, consider placing Fig.10 in section 2.2.3.
8. Discussion of the Results: the efforts of the Authors are recognised, however, the additional explanations are often blurred, and their readability is generally tough. As an example, explanation in lines 255 - 260 is unclear, since the effects of superplasticizer are not mentioned before. The effects of each test variable (superplasticizer, micro-silica content, fine/coarse aggregates replacement ...) should be evaluated and discussed in a more rigorous way. In addition, statements in lines 373-376 is still a mere description of the findings already evident in Fig.12.
9. Even if it is a reasonable choice, the adoption of logarithmic data fittings must be explained. E.g. in Fig. 11, only 2 fitting points are available (3 days and 28 days) and several fitting functions could have been used. With reference to Fig 11, the fitting rationale is necessary to endorse what stated in lines 358-366, otherwise not reliable.
10. The exposition of the mechanical testing results at the hardened stage still appears like a technical report rather than a scientific paper. Again, only superficial hypotheses on the mechanisms involved in the system are developed in the discussion. No images of the cracked samples, and no investigation of the microstructure (which is crucial for the understanding of the mechanical behaviour) are reported, as well as a critical assessment of the findings is not conducted, by taking into account the available literature. 

Despite the Authors have addressed some of my remarks, the discussion section still requires a thorough revision, and the language quality of the manuscript should be significantly improved before the paper may be suitable for publication.

Author Response

Dear Reviewer,

We greatly appreciate the opportunity you give us to improve the paper with your valuable comments. Here you can find the detailed comments and performed changes. You can find the applied changes in the attachment file. Please see the attachment.

 

Best regards,

The authors

Author Response File: Author Response.docx

Round 3

Reviewer 2 Report

The comments of my first report have been addressed by the authors.

Reviewer 3 Report

The Authors have broaden their study, providing new tests and more informative discussion.

My concerns have been sufficiently addressed by the Authors. I only advise to carry out a spell-check (e.g. 3.3 SEM analysis/analyses", and UNI-EN 12390-5:2020).