Life Cycle Assessment of Waste Glass Powder Incorporation on Concrete: A Bridge Retrofit Study Case

Round 1

Reviewer 1 Report

This article evaluates both the technical and environmental performance considering a Life Cycle Assessment of the materials. A technical solution for the retrofit of the Third Bridge of Vitoria, an important intercity urban connector is used as an example.

The article is generally understandable, although in some sections it is not fluent enough. It contains some errors to be fixed.

Few aspects of the procedure used need to be further clarified to improve readability and overall quality.

In my opinion the document corresponds to the objectives of the magazine, if the paper is considered for publication by the publisher, it is necessary to make a major revision:

• Introduction: The purpose of the research should be better defined.
• Line 59: I suggest you edit the sentence to: "The considered glass waste is.....".
• Lines 62-70: The indications of the template are reported. Delete.
• Line 73: "Subsection"? It is necessary to check
• Line 79: "Premisses" or premises? It is necessary to check
• Lines 109-114: The sentences are not very clear. I suggest to improve them.
• Figure 5: I suggest changing the lines color.
• Section 2.4.2: I suggest specify the number of specimens used.
• Line 167: What is equation 1.1 refers to?
• Table 2: There is a need to better comment on the results. Specify the number of specimens used for each type. I suggest referring to the following papers:

                doi.org/10.3390/ma14030598

                doi.org/10.1016/j.culher.2017.10.009

• Table 3: I suggest improving the graphics.
• Section 2.5.1: To evaluate the service life prediction, only the attack by chloride is considered. Several researches deal with this topic, I suggest to investigate the following papers:

                doi.org/10.3390/infrastructures6110164

                doi.org/10.1016/j.prostr.2018.11.051

                doi.org/10.2478/bpasts-2013-0016

• Lines 204-205: I suggest better explaining the relation with experimental analysis.
• Subsections 2.6.4, 2.6.5 and 2.6.6: I suggest to merge subsections 2.6.4, 2.6.5 and 2.6.6. Subsection 2.6.5 is a bit difficult to follow. The data are reported in the table, they could be omitted in the text, giving more space for comparison considerations.
• Table 4: I suggest improving the graphics
• Subsections 2.6.9 and 2.6.10: Can they be merged? The title is the same
• Lines 319-320: It is necessary to check.
• Line 384: "Mohan" et al. It is necessary to check.
• Lines 394-396: The sentences are not very clear. I suggest to improve them.
• Line 409: Please clarify
• Conclusion: Must be rewritten considering the changes made to the paper
• References: The required formatting is not applied.

Some general comments:

• Replace the word "work" with "paper".
• I recommend inserting the figures and tables in the sections.

Author Response

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Reviewer 2 Report

The impact of waste glass powder incorporation on concrete on the durability of the structure was analyzed. Elements of the structure in which 20% of cement has been replaced by waste glass powder were analyzed. The analysis was based on laboratory tests in which rapid chloride permeability test and chloride diffusion coefficient  tests were performed. Using the chloride diffusion coefficients, and adopting the Fick second law of diffusion in the non-steady-state, it was possible to generate a graph of concrete service life versus chloride penetration depth.
The authors showed an analytical model of environmental impact: compression strength versus environmental impacts and chloride penetration resistance versus environmental impacts. Then the repair necessity assessment for 100 years period and total endpoint environmental impacts in 100 years was shown.
I consider the presented paper important for the use of the bridge, but it does not have any important scientific achievements.
However, since it shows a scientific research application in real construction, it should be presented in the Journal Applied Science.

Author Response

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Reviewer 3 Report

This paper deals with the Life cycle assessment of waste glass powder incorporation on concrete: a bridge retrofit study case. There are also some places should be addressed before it can be accepted.

1. Generally, the main aim to use supplementary cementitious materials (SCM) is to improve the properties of concrete, not solely to reduce cement consumption. For instance, the silica fume was used to produce high strength concrete, the fly ash was adopted to produce low temperature-rising concrete, etc. I think the authors should clarify this point, at least, they should enrich the statement of the sentence “cement replacements in concrete mixture usually improve the performance”, in order to make the state-in-art more comprehensive. For this sake, many specific SCMs and their benefits should be added, some related references can improve the introduction part, such as Effects of fineness and content of phosphorus slag on cement hydration, permeability, pore structure and fractal dimension of concrete; Pore structural and fractal analysis of the influence of fly ash and silica fume on the mechanical property and abrasion resistance of concrete
2. The current study of the influence of waste glass powder on concrete should be well introduced in the introduction part.
3. I think the authors should be more careful, since they forget to delete the previous comments “introduction should briefly place the study in a broad context and highlight why it is important. It should define the purpose of the work and its significance. The current state of the research field should be carefully reviewed and key publications cited. Please highlight controversial and diverging hypotheses when necessary. Finally, briefly mention the main aim of the work and highlight the principal conclusions. As far as possible, please keep the introduction comprehensible to scientists outside your particular field of research. References should be numbered in order of appearance and indicated by a numeral or numerals in square brackets—e.g., [1] or [2,3], or [4–6]. See the end of the document for further details on references.” This comment is reasonable, however, the authors obviously did not revise accordingly. Hence, I suggest the authors should at least address the comment “introduction should briefly place the study in a broad context and highlight why it is important. The current state of the research field should be carefully reviewed and key publications cited.”
4. I will suggest acceptance of this paper only if the comments above are fully included.

Author Response

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Reviewer 4 Report

Page 2, line 48-49. What indicators are the authors talking about? No references about the environmental benefits are presented.

Page 3, line 141-148. No size for GP1 is presented, which was crushed using a mortar and pestle, only for GP2 (on line 148). What volume was obtained of ground glass powder during the 2 h of milling, either GP1 and GP2, and what technique was used? Mortar and peste and, ball milling were used for the laboratory analysis.

Afterwards, the authors do not mention about the milling process, no even the LCA or LCIA contribution for this process, they focus on the different drying process.

Page 4, line 166-167. Equations 1 and 1.1?

Page 5, line 197. No different milling options were discussed along the text.

Page 5, line 230-235. Perhaps and image can help to visualize the system.

Page 6, line 244. Water/h.m3 … check units

Page 6, line 251. What “RV” stands for?

Page 8, line 343. Life Cycle impact Analysis (LCIA)  …  in your text you do not mention what LCIA stands for, i.e. Line 353.

Most of the labels or legends on figures 10, 11, 12, 13 and 15, must be check their font size are too small.

On table 2 and 3, perhaps a separation line between each concept on column 1, could help to separate between each other. Same for table 4, column 3.

Author Response

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Round 2

Reviewer 1 Report

The authors have reviewed the paper extensively, however some suggestions have not been fully addressed.

Author Response

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Reviewer 3 Report

The authors did a careful revision work. However, I found my previous comment Point 1 was not fully addressed. In addition, some newly added references are old and can be replaced by the new ones. The authors should unstand the suggestions of the reviewer proposed to improve this paper.

Author Response

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Round 3

Reviewer 3 Report

It can be accepted, but there are some language problems which can be carefully improved during proof.