Properties of Bacterial Copper Slag Concrete
Round 1
Reviewer 1 Report
The manuscript reports laboratory tests and numerical analysis on reinforced concrete beams with bacterial copper slag.
In its current form, the manuscript is hard to read/understand, and it needs significant editing to fix the language and presentation. The authors are encouraged to use the services of a professional. MDPI has an editing service for all authors. The link to the service website is here: MDPI Author Services
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Reviewer 2 Report
This study aimed to investigate the properties of bacterial copper slag concrete. By replacing different amounts of fine aggregate with copper slag, five concrete mixtures were formed, ranging from 0% to 100%. Bacterium subtilis was added at 1% to 2% by weight of cement during concrete pouring. The compressive and flexural strengths of fractured specimens replaced with microbially repaired copper slag were evaluated. Test results showed that replacing 50 to 75 percent of sand with copper slag could produce concrete with superior mechanical properties and higher density. Under the optimal ratio of copper slag and microorganisms, suitable RCC beams were formed. The paper is interesting and useful for practicing engineers. The following comments are suggested:
1. The authors should cite more recent publications in their literature review.
2. It is recommended to include the content of 3.1 Basic properties of concrete materials in 2.1 Materials.
3. The authors should describe in more detail the manner in which the bacteria were added.
4. There are four figures in Figure 4, and their contents should be explained separately.
5. The resolution of Figures 14-16 should be improved.
6. The authors should provide SEM photographs of calcium carbonate crystals in concrete.
7. According to the test results of various mechanical properties, it is advisable to deeply analyze the influence mechanism of each test variable.
8. It can be seen from Figure 17 that with a 75% copper slag replacement and 2% bacteria, the flexural load of the specimen increases, but its toughness decreases. Its mechanism should be analyzed in depth.
9. There are some spelling mistakes in the text, which should be corrected.
10. There should be a space between the number and the unit.
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Reviewer 3 Report
The paper is focused on the mechanical properties of bacterial copper slag concrete. The paper is in general well structures and written. However, the following challenge is presented to the authors in order to improve the paper :
1-Intoduction
Highlight the novelty of this work, as well as the importance of the results obtained.
2-10 Analysis of beam modelling using Abaqus
What are the parameters introduced in the model for each type of beam to simulate the effect of Copper slag or bacteria?
3 Results
3-1 Basic properties of concrete materials
It is more coherent if you put this section in the 2-1 Materials part.
In all the sections of the Results part, the authors only describe the results without analyzing them and explaining why these results are found and why the optimum strength corresponds to 75% incorporation. There are many questions that remain unanswered.
Is there any difference between the different concretes concerning their properties in the fresh state?
Concerning the numerical part, it is necessary to provide the input parameters for each material so that one can understand the results found or criticize them
Some remarks on the form:
line 127, the sentence (0,1, and 2 percent by weight of cement) is repeated.
Figures 15 and 16 have the same heading.
figures 19-b and 19-c have the same heading written on the figure
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Reviewer 4 Report
Copper slag has a promising future in the construction industry as an alternative fine aggregate. The impact of microorganisms on the mechanical properties and flexural behaviour of copper slag concrete is investigated in this study. The compressive strength results indicated that the density and porosity of copper slag concrete had increased. Nevertheless, more than 40 percent of Copper Slag replacement resulted in an increase in Compressive Strength compared to the control concrete. MICP is an innovative new phenomenon that has the potential to enhance the quality of copper slag concrete. It can be stated that a 75% copper slag replacement of fine aggregate treated with 2% bacteria could be a viable alternative to regular conventional concrete,resulting in enhanced concrete performance.
Chapter: 2.1 Materials
- what proportions of aggregate were used (20mm-sized crushed angular aggregate, and locally accessible river sand)
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Reviewer 5 Report
Subject the copper slag to elemental XRF analysis or phase analysis (mineralogical analysis)
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Round 2
Reviewer 1 Report
Now that the language has been improved, the manuscript needs some technical revisions to fix the following issues:
1. The finite element model results look too close to the experimental results; this has to be explained. How did you include bacteria's effect in the numerical model?
2. Since you have a finite element mode, why not go beyond the peak and analyze the post-peak behavior until the beams collapse?
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Reviewer 3 Report
The authors have taken into account the reviewer's comments.
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Round 3
Reviewer 1 Report
The reviewer is satisfied with the response provided by the authors.
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