3D X-ray Micro-CT Analysis of Rebar Corrosion in Reinforced Concrete Subjected to a Chloride-Induced Environment
Round 1
Reviewer 1 Report
The paper is interesting but following are the minor changes to be done before publication.
- Title is too long and confusing. Please modify.
- In last line of abstract correct 0,25mm.
- Fig. 2 and Fig. 8 seems unclear. please provide a schematic diagram for better understanding.
- Explain why 28 days results are not considered.
- Add a discussion section before conclusion for practical implementation of current study.
- In conclusion, modify the first paragraph. in point two use "respectively" to make sentence clearer. In point 4, correct 0,25mm.
- what are the future suggestion regarding this work.
Author Response
Dear Reviewer
Thank You very much for the evaluation of our manuscript. We have taken into account all remarks and comments. The changes in the text have been highlighted in yellow.
Ad. 1: Title is too long and confusing. Please modify.
Title has been modified – it was shortened.
Ad. 2: In last line of abstract correct 0,25mm.
In our opinion the maximum crack width is correct.
Ad. 3: Fig. 2 and Fig. 8 seems unclear. please provide a schematic diagram for better understanding.
Schematic diagrams were added.
Ad. 4: Explain why 28 days results are not considered.
Actually, X-ray tests were carried out every 14 days, thus 28 days and 56 days tests are also available. However, since no significant changes between 14 days and 28 days as well as 42 days and 56 days were visible, this results were not presented in our paper.
Ad. 5: Add a discussion section before conclusion for practical implementation of current study.
Discussion section was added.
Ad. 6: In conclusion, modify the first paragraph. In point two use "respectively" to make sentence clearer. In point 4, correct 0,25mm.
Conclusions were improved.
What are the future suggestion regarding this work.
Future perspectives were added.
Kind Regards
Aleksandra Malachowska
Reviewer 2 Report
Rebar corrosion due to chloride ingress is not new. There are multiple publications (e.g. by fib, ACI and RILEM) and journal papers on durability of concrete structures addressing this and other relevant topics. Accelerated chloride ingress seems not to have been performed according to a current method, thus results cannot be compared. Bond tests seem not to have been performed according to a standard, e.g., EN 10080; this would have prevent concrete splitting mode failure; thus conclusions regarding rebar-to-concrete bond behaviour cannot be drawn. For short, the only innovative aspect of this paper seems to be the use of 3D X-Ray micro CT analysis (at least I am not aware of similar studies) and thus only conclusions (2) and (3) have some relevance. The editor has to decide if this is enough to justify the publication of this paper.
Author Response
Dear Reviewer
Thank You very much for the valuable remarks concerning our manuscript.
Rebar corrosion due to chloride ingress is not new. There are multiple publications (e.g. by fib, ACI and RILEM) and journal papers on durability of concrete structures addressing this and other relevant topics. Accelerated chloride ingress seems not to have been performed according to a current method, thus results cannot be compared. Bond tests seem not to have been performed according to a standard, e.g., EN 10080; this would have prevent concrete splitting mode failure; thus conclusions regarding rebar-to-concrete bond behaviour cannot be drawn. For short, the only innovative aspect of this paper seems to be the use of 3D X-Ray micro CT analysis (at least I am not aware of similar studies) and thus only conclusions (2) and (3) have some relevance. The editor has to decide if this is enough to justify the publication of this paper.
There is no doubt that the phenomenon of rebar corrosion due to chloride is not new and a number of publications is available. However, there are 2 main objectives of this study that also represent its novelties:
- Detailed and thorough 3D experimental measurements and analyses of reinforcement loss due to corrosion and its influence on concrete microstructure by means of X-ray micro-computed tomography
- 3D X-ray micro-computed 3D investigations of fracture in reinforced concrete samples subjected to pull-out tests.
Moreover, reinforced concrete specimens, of a relatively small geometry, were used in order to provide the ability to scan them entirely in the micro-CT system. Thus, tests were not performed according to any standard.
However, it is important to investigate the corrosion phenomenon and bond failure mechanism at the aggregate level. Later experimental tests will be simulated using isotropic coupled elasto-plastic-damage constitutive model for concrete enhanced by a characteristic length of micro-structure in terms of integral non-local theory. Since the heterogeneity of tested material has a strong impact on the local phenomena such as the mechanism of the initiation, growth and formation of fracture which finally are responsible for the macroscopic behaviour of material. Thus, concrete will be realistically described as a four phase material composed of cement matrix, aggregate particles, interfacial transition zones ITZs and macro voids assumed on a basis of X-ray micro-CT images taken during experimental tests. Additionally, at this level of accuracy, ribs of the steel bars will be modeled as well. The final goal is to introduce a new enhanced bond-law taking into account material heterogeneity.
Kind Regards
Aleksandra Malachowska
Reviewer 3 Report
Dear authors,
The paper explains 3D X-Ray micro-CT analysis of the concrete cover protective ability to counteract rebar corrosion in reinforced concrete in the chloride-induced environment and well organized however the following comments will match it more with the Journal criteria:
1) More than 70% of the references are newer than 2016 which shows the recent similar work reviews by the author however still lack of most recent ones are clear. Please add 3 more recent works (2020-2021).
2) Section 2, the significance of corrosion under sulfates are also now common in practical projects. Are the authors also aware of this action?
3) Section 3: is the current concrete mixture in correlation with a special structural mixuter?
4) The paper missed an important section "Discussion". It only demonstrates the test result with no further scientific discussion. Please revise and add the section with a comprehensive discussion.
5) Conclusion should be further revised based on the previous comment.
6) English need to be checked by a native English technical speaker.
Author Response
Dear Reviewer
Thank You very much for the valuable remarks concerning our manuscript. We have taken into account all remarks and comments. The changes in the text have been highlighted in blue.
The paper explains 3D X-Ray micro-CT analysis of the concrete cover protective ability to counteract rebar corrosion in reinforced concrete in the chloride-induced environment and well organized however the following comments will match it more with the Journal criteria.
Ad. 1: More than 70% of the references are newer than 2016 which shows the recent similar work reviews by the author however still lack of most recent ones are clear. Please add 3 more recent works (2020-2021).
Some recent publications were added.
Ad. 2: Section 2, the significance of corrosion under sulfates are also now common in practical projects. Are the authors also aware of this action?
Actually, we are not aware of this fact. However, due to our best knowledge, it is still not considered in practical approach in Poland.
Ad. 3: Section 3: is the current concrete mixture in correlation with a special structural mixture?
Assumed concrete mixture is a typical structural mixture used on the construction site. Presented mixture was used during construction of multi-family building with underground garage.
Ad: 4: The paper missed an important section "Discussion". It only demonstrates the test result with no further scientific discussion. Please revise and add the section with a comprehensive discussion.
“Discussion” section was added.
Ad: 5: Conclusion should be further revised based on the previous comment.
Conclusions were revised.
Ad: 6: English need to be checked by a native English technical speaker.
Paper was carefully checked.
Kind Regards
Aleksandra Malachowska
Reviewer 4 Report
[1] line 65; Check the subscript.
[2] line 79; Electron, not electrion
[3] Figure 1; Exposed rebar shall be insulated by any epoxy coating to protect the induction of corrosion from the salt solution.
[4] Figure 9; What means a) and b)? If possible, insert the meaning into the figure- 0 day or 70 days
[5] Conclusions is too long as like the summary. Please rewrite them.
[6] References
1) Check 'and' or '&'
Author Response
Dear Reviewer
Thank You very much for the valuable remarks concerning our manuscript. We have taken into account all remarks and comments. The changes in the text have been highlighted in green.
Ad. 1: line 65; Check the subscript.
Subscript was corrected.
Ad. 2: line 79; Electron, not electrion
Misspelled word was corrected.
Ad. 3: Figure 1; Exposed rebar shall be insulated by any epoxy coating to protect the induction of corrosion from the salt solution.
Thank You very much for this remark. In the presented tests no epoxy coating was added, however, in the future test, we will insulate exposed rebar.
Ad. 4: Figure 9; What means a) and b)? If possible, insert the meaning into the figure- 0 day or 70 days
Figure was improved.
Ad. 5: Conclusions is too long as like the summary. Please rewrite them.
Discussion section was added. Conclusions were rewritten and shortened.
Ad. 5: References. Check 'and' or '&'
All ‘&’ were replaced with ‘and’.
Kind Regards
Aleksandra Malachowska
Round 2
Reviewer 3 Report
Dear Authors,
Thanks for the corrections.
