Protection of Reinforced Concrete Steel Exposed to a Marine Environment: A Preliminary Onsite Study of the Performance of a New Generation of Surface-Applied Corrosion Inhibitors

Round 1

Reviewer 1 Report

manuscript presented include information related to the use of impregnation-based corrosion inhibitors for reinforcement steel in concrete. The following are some concerns that the authors should take into consideration to improve the manuscript:

1. Page 1, line 10: After author affiliations there is no space line with the section Abstract.

2. Page 3, line 95: Apparently “Corrosion inhibitors in repair and refurbishment of reinforced concrete” is a section, thus, follow format for section titles.

3. Page 4, line 133: Eliminate all brand names. Include chemical components only, without company names or brand names.

4. Page 6, lines 234 and 237: Eliminate all brand names.

5. Page7, line 242: Eliminate all brand names.

6. In Table 2 authors show results from only two powder sampling for the entire wall extension. This is not statistically representative for a detail inspection in chloride-laden environments. It is also interesting to observe that the amount of chlorides a the two sampled depths were almost identical in sample 1 and no differences were observed in sample 2. Could be the case that the powders were contaminated during handling? There is no detailed explanation how the samples were taken and stored before reaching laboratory facilities. Or could be that the original concrete was contaminated by chlorides due to concrete curing accelerators?

7. Page 9-10: The electrical resistivity method used with the equipment shown was to obtain the apparent electrical resistivity and not the saturated electrical resistivity, where cores are extracted and before performing the measurement, cores are water saturated to use the values reported in Table 3. Authors need to be sure if the ranges in Table 3 are for saturated concrete resistivity or apparent concrete resistivity.

8. Page 9-19: Data obtained from the equipment shown regularly need to be multiplied by a geometry factor (or shape factor) depending on the size of the cylindrical/prismatic specimen or structure thickness. Do authors check if the wall thickness was enough to avoid misleading resistivity results? Is the wall thickness enough to consider the electrical resistivity as for a semi-infinite media, where the formula is ρ=2πRe (Re is the electrical resistance of the semi-infinite media)?

9. Every histogram results presented in Figure 10 are an average of how many measurements, or the measurements per date are only four point determinations? Why the results are nor presented as resistivity mapping to have a more realistic data set and not only four histogram bars per date? For example, Nexp 1 has an evaluation area of 2.0x0.65 m. Why the measurements are presented as a single histogram bar and not as a resistivity mapping?

10. Same comment as per comment (9) with the corrosion potential results presented in Figure 11. Authors need to include the potential mappings of the four regions evaluated (Nexp1 – Nexp4).

11. Same comment as per comment (9) with the corrosion rate results presented in Figure 12. Authors need to include the corrosion rate mappings of the four regions evaluated (Nexp1 – Nexp4).

12. There are some tables that have the description of the table before the actual table, and there are others where such description are after the table. Authors need to have same format for all tables and figures.

13. Authors present interesting field measurements and very little discussion of the results. For example, people that are working on durability forecasting based on corrosion rate and resistivity measurements correlates both experimental values and have found interesting correlations between electrical resistivity and corrosion rate (i.e. Dr Carmen Andrade have studied this correlation with excellent results). Authors need to plot correlation graphs between electrical resistivity vs icorr (corrosion rate), or corrosion potential (Ecorr) vs icorr to see trends from the obtained results of this investigation and compare the results obtained with data form the literature and corroborate the empirical correlations published in the literature with the actual results.

Author Response

Paper review for Rev.1 (27-08-2022)

Thank you so much for your detailed review, we appreciate your dedication and effort. Please, find the comments, appreciations and fixes below, in blue color. Please find attached the new version with the principal changes marked in red.

1. Page 1, line 10: After author affiliations there is no space line with the section Abstract. Done.
2. Page 3, line 95: Apparently “Corrosion inhibitors in repair and refurbishment of reinforced concrete” is a section, thus, follow format for section titles. Done.
3. Page 4, line 133: Eliminate all brand names. Include chemical components only, without company names or brand names. Done.
4. Page 6, lines 234 and 237: Eliminate all brand names. Done.
5. Page7, line 242: Eliminate all brand names. Done.
6. In Table 2 authors show results from only two powder sampling for the entire wall extension. This is not statistically representative for a detail inspection in chloride-laden environments. It is also interesting to observe that the amount of chlorides a the two sampled depths were almost identical in sample 1 and no differences were observed in sample 2. Could be the case that the powders were contaminated during handling? There is no detailed explanation how the samples were taken and stored before reaching laboratory facilities. Or could be that the original concrete was contaminated by chlorides due to concrete curing accelerators?

• Test samples were taken using as reference RILEM TC 178-TMC recommendations (5.1 dry drilling method). Although for profile chloride determination, the total profile is recommended to be around 5-8 steps of 5 mm each, the aim of this test is not to obtain a chloride profile but a percentage over cement weight, in order to test the boundaries of the DP-SACI and to demonstrate the corrosion was due to chloride contamination. The objective it is not to investigate representatives areas of the entire wall extension, but to know the chloride content at the superficial area (0-25 mm)near the rebar (25-60 mm). The main interest is to clarify the effectiveness of DP-SACI in high levels chloride contaminated concrete.
• The information provided by the quality control of the construction works do not mention that external chlorides contamination due to curing agents were a possibility. 

7. Page 9-10: The electrical resistivity method used with the equipment shown was to obtain the apparent electrical resistivity and not the saturated electrical resistivity, where cores are extracted and before performing the measurement, cores are water saturated to use the values reported in Table 3. Authors need to be sure if the ranges in Table 3 are for saturated concrete resistivity or apparent concrete resistivity.

     Icorr is controlled by real electrical resistivity in on-site measures, not for the saturated one, and its relationship it is explained at the new graphic included at the conclusions (thank you for your suggestion again). Values showed as reference in table 3 are related to concrete structures not water saturated. We assume that concrete resistivity changes in real structures and the experimental method takes in consideration intrinsic changes of the temperature, so that values obtained provides a relevant information in this situation for the aim of this study. Taking in consideration the change of resistivity measured in different seasons (as mentioned with the intrinsic consideration of changes of temperature) the important conclusion is that electrical resistivity increase is maintained in different real conditions due to the effectivity of the product.

8.  Page 9-19: Data obtained from the equipment shown regularly need to be multiplied by a geometry factor (or shape factor) depending on the size of the cylindrical/prismatic specimen or structure thickness. Do authors check if the wall thickness was enough to avoid misleading resistivity results? Is the wall thickness enough to consider the electrical resistivity as for a semi-infinite media, where the formula is ρ=2πRe (Re is the electrical resistance of the semi-infinite media)?

     Real structures or large areas we consider a semi-infinite media so we do not need to use a geometric o shape factor and we can consider the expression (ρ=2πRe). Thickness is not a relevant parameter for resistivity in large on-site measures because Wenner array only takes values from the superficial area (a couple of cm depending of the concrete quality and its porosity). In any case, the sea wall has 1m thickness.

9. Every histogram results presented in Figure 10 are an average of how many measurements, or the measurements per date are only four point determinations?

     Usually, we do 2 measures for each point (there are four points named Nexp 1 to 4), in order do not induce a polarisation of the rebar. If there is a concordance are the values are close, then you represent the average value.

10. Why the results are nor presented as resistivity mapping to have a more realistic data set and not only four histogram bars per date? For example, Nexp 1 has an evaluation area of 2.0x0.65 m. Why the measurements are presented as a single histogram bar and not as a resistivity mapping? See point nº 10.

Same comment as per comment (9) with the corrosion potential results presented in Figure 11. Authors need to include the potential mappings of the four regions evaluated (Nexp1 – Nexp4)

      (10,11) Mapping is used in large areas and it is used for having a general overview of the structure, or to identify corroded areas. In this case, the corroded area was found and selected attending customer´s requirements (near the joint) and according the size of the region to be measured and investigated over the time.

     The representation by histogram is based in showing how is the evolution of the different parameters after DP-SACI application and how good is the performance of the corrosion control at this area.

(10-11)  In the case of resistivity, 2 or 3 measures are taken around the concrete in each area (avoiding the rebar) and if values are in the same range, the result shown is the average. For Icorr, usually 2 measures are taken for each point (there are four points/regions named Nexp 1 to 4), in order do not induce a polarisation of the rebar. If there is a concordance are the values are close, then you represent the average value too. The representation by histogram represent how is the evolution of the different parameters after DP-SACI application, and how good is the performance of the corrosion control at this area.

11. Same comment as per comment (9) with the corrosion rate results presented in Figure 12. Authors need to include the corrosion rate mappings of the four regions evaluated (Nexp1 – Nexp4).

      See previous explanation. On the other hand, mapping information shows you the  combined results between Ecorr and resistivity, provides a corrosion risk (probability) instead of a corrosion rate.

12. There are some tables that have the description of the table before the actual table, and there are others where such description are after the table. Authors need to have same format for all tables and figures. Done.
13. Authors present interesting field measurements and very little discussion of the results. For example, people that are working on durability forecasting based on corrosion rate and resistivity measurements correlates both experimental values and have found interesting correlations between electrical resistivity and corrosion rate (i.e. Dr Carmen Andrade have studied this correlation with excellent results). Authors need to plot correlation graphs between electrical resistivity vs icorr (corrosion rate), or corrosion potential (Ecorr) vs icorr to see trends from the obtained results of this investigation and compare the results obtained with data form the literature and corroborate the empirical correlations published in the literature with the actual results.

     Thank you for your advice, there is a very interesting field regarding this issue that has been not included due to time schedule. Please, find attached the manuscript with the conclusions according your request, that have been included at the “discussion section” in red color as mentioned at the beginning.

Best regards,

Diana Martín.

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper investigates the surface applied corrosion inhibitors. Generally, it's an interesting paper. It can be considered if the authors can improve it based on the comments seriously.

(1) The title was should be more concise.

(2) About the materials, the authors should introduce more detailed information at first.

(3) The results of the experimental test should be analyzed and discussed more clearly by taking into considered some basically theories.

Author Response

Thank you so much for your detailed review, we appreciate your dedication and effort. Please, find the comments, appreciations and fixes below, in green.

• The title should be more concise.

Other titles were considered as the showed below, but other reviewers considered this one as the most accurate:

• • A preliminary onsite study of the performance of new generation of surface applied corrosion inhibitors in marine structures affected by chloride corrosion.

• • New generation surface applied corrosion inhibitor for corrosion mitigation in marine environments, based in dual- phase technologies.

(2) About the materials, the authors should introduce more detailed information at first. Done.

(3) The results of the experimental test should be analyzed and discussed more clearly by taking into considered some basically theories. Done.

Conclusions has been improved, including some references and analysis between relationship between Icorr and electrical resistivity, regarding some previous investigators. Done.

• • Andrade, C. and Alonso, C. Test methods for on-site corrosion rate measurements of steel reinforcement in concrete by means of the polarization resistance method. Materials and Structures, Vol.37 November 2004, pp 623-643.
  • Andrade, C. Fullea, J. and Alonso, C. The use of the graph corrosion rate-resistivity in the measurement of the corrosion current, Workshop of Measurement and Interpretation of On-Site Corrosion Rates, Mesina, Rilen PRO 18, Andrade, Alonso, C., Fullea, J., Polimón, J and Rodriguez, J. Ed., RILEM b, MADRID (Feb 1999) 157-165.

 Please find attached the new version with the principal changes marked in red.

Best regards,

Diana Martín

Author Response File: Author Response.pdf

Reviewer 3 Report

The research subject is very interesting. Although more technical than scientific, the submitted work is interesting indeed. Performance assessment of field application of construction products is most welcome. Although reporting valuable results, this work is a bit short both on number of assessments and on the timeframe. Furthermore, when the authors report problems in some of the few carried measurements. Certainly, readers will look forward for more substantial information. Therefore, authors are encouraged to proceed with the monitoring and to materialize their intention of sharing future results. 

Overall, the manuscript is fine. Still, there are some minor issues, easily addressable, that when overcome will improve the quality of the paper. 

Figure 1 – Tuutti's model is not quite like depicted in this figure: It does not consider “repair”; further, it is not clear if “End of service life” stands for the red or the black dotted lines; Propagation does not necessarily stops by repairing the reinforced concrete; Corrosion is not necessarily “rapid”, usually the terms “steel corrosion” or “active corrosion” are adopted.  

Ln 51, 95 and others – some subtitles are missing numbering 

Ln 53-93 the structure of the text can be improved and traces of repetition can be avoided. Usually, the chloride ingress is described prior to the active corrosion process. 

Ln 96 Organization  

Ln 124 clarify if the limits concern depth or width 

Check for consistency throughout the document on using final dot at the end of titles, subtitles and captions, as well as on placing tables’ caption whether before or after the tables 

Ln 183 at a molecular level 

It seems ambiguous the construction year, considering info on line 196 and Table 1 

Still on table 1, what is the use/meaning of the information in the upper right cell? 

Also concerning Table 1, bottom left cell is not it “Target/intended service life”? 

Ln 271 Please report the date of testing 

Try to avoid so many references to the commercial name of the product. Once in the text is surely enough (this comment was settled before reaching the conflicts of interest statement). Within this please check the document for consistency on using SACI or DP-SACI when referring to the product. 

Ln 312 usual instead of habitual 

Ln 316 and 318 Layers instead of coats 

Ln 356, 359, 364, … please remove extra dots 

Ln 360-363 If the concrete has not (nearly) the same moisture content in every measurement, then the measurements cannot be used for product’s performance assessment. Therefore, the presented feature is out of context and shall be removed from the text. 

Ln 372-373 please revise the sentence as it is not clear 

Ln 392-392 please use brackets or a footnote, for information on the reference electrode 

Table 4 Please check font type consistency in left column 

Ln 401 Please make a reference to Figure 6 

Figures 10, 11 and 12 Please remove the titles from the charts 

Ln 424-426 Please consider adding a reference to the green dashed line 

Ln 428-429 Rephrase sentence between brackets as it is not clear 

Ln 437 Figure 11? 

Ln 456 more negative higher than lower? 

Ln 457 in at ? 

There is no reference to table 7 in the text 

In the acknowledgements section it is not clear who is the author who is doing each acknowledgment

Author Response

Thank you so much for your detailed review, we appreciate your dedication and effort. Please, find the comments, appreciations and fixes below, in orange color. Please find attached the new version with the principal changes marked in red.

1. Figure 1 – Tuutti's model is not quite like depicted in this figure: It does not consider “repair”; further, it is not clear if “End of service life” stands for the red or the black dotted lines; Propagation does not necessarily stops by repairing the reinforced concrete; Corrosion is not necessarily “rapid”, usually the terms “steel corrosion” or “active corrosion” are adopted. Clarified.
2. Ln 51, 95 and others – some subtitles are missing numbering. Done. Notice that several changes affected the line number.
3. Ln 53-93 the structure of the text can be improved and traces of repetition can be avoided. Usually, the chloride ingress is described prior to the active corrosion process. Done.
4. Ln 96 Organization. Done.
5. Ln 124 clarify if the limits concern depth or width. The main difference between them is that depth measures from exterior to interior, while width measures from side to side.
6. Check for consistency throughout the document on using final dot at the end of titles, subtitles and captions, as well as on placing tables’ caption whether before or after the tables. Done.
7. Ln 183 at a molecular level. Done.
8. It seems ambiguous the construction year, considering info on line 196 and Table 1. Ln 249.
9. Still on table 1, what is the use/meaning of the information in the upper right cell? It´s the Spanish classification according EHE-08, Spanish Code for Structural Concrete. 2008 (43) Also concerning Table 1, bottom left cell is not it “Target/intended service life”?  Done. Service life design.
10. Ln 271 Please report the date of testing. Done.
11. Try to avoid so many references to the commercial name of the product. Once in the text is surely enough (this comment was settled before reaching the conflicts of interest statement). Improved in any case. Within this please check the document for consistency on using SACI or DP-SACI when referring to the product. The difference is that SACI has not a dual -phase surface applied corrosion inhibitor (DP-SACI).
12. Ln 312 usual instead of habitual. Done.
13. Ln 316 and 318 Layers instead of coats. Done.
14. Ln 356, 359, 364, … please remove extra dots. Done.
15. Ln 360-363 If the concrete has not (nearly) the same moisture content in every measurement, then the measurements cannot be used for product’s performance assessment. Therefore, the presented feature is out of context and shall be removed from the text. Change of electrical resistivity is normal in real structures, so electrical resistivity is a electrochemical parameter used to evaluate the performance of surface applied corrosion inhibitors ( or DD-SACI). That is the aim of testing in different conditions, where the important conclusion is that the effectivity is proven in all of them.
16. Ln 372-373 please revise the sentence as it is not clear. Done.
17. Ln 392-392 please use brackets or a footnote, for information on the reference electrode. Done. 
18. Table 4 Please check font type consistency in left column. Done.
19. Ln 401 Please make a reference to Figure 6. Done.
20. Figures 10, 11 and 12 Please remove the titles from the charts. Done.
21. Ln 424-426 Please consider adding a reference to the green dashed line. Done.
22. Ln 428-429 Rephrase sentence between brackets as it is not clear. Done.
23. Ln 437 Figure 11? Done.
24. Ln 456 more negative higher than lower? Done.
25. Ln 457 in at ? Done. There is no reference to table 7 in the text. Done.
26. In the acknowledgements section it is not clear who is the author who is doing each acknowledgment. Done.                                                                              Best regards,

                                                                                       Diana Martín

Author Response File: Author Response.pdf

Reviewer 4 Report

This study investigates the development of new surficial inhibitors for steel in the marine environment. The study has the potential to add knowledge to the existing useful literature. However, some technical and language revisions are required before it is considered for publication.

1.       The article needs a major revision to improve the flow of contents.

1.       The title must be revised in a way that it should be self-explanatory, rather than creating ambiguity.  

2.       Please revise the abstract to describe the study and the most important takeaways.

3.       Please specify the major findings in the abstract as well.

4.       Figure 1 should be referred to if it is from the literature.

5.       More literature review is needed in the introduction, the current manuscript (intro) lacks up-to-date literature.

6.       It is suggested not to create a subsection in the introduction unless it is unavoidable. Follow the overall formatting guidelines of the journal.

7.       Lines 105 to 135 need revision for describing the research novelty.

8.       In suggestion 7, incorporate the literature in a sequential order to develop a conclusive paragraph mentioning the novelty of this study.

9.       Section 2.1 heading needs revision.

10.   Dual-phase corrosion inhibitor explanation in section 2.1 must be referred.

11.   It has been mentioned that the wash-out would elongate due to a dual-phase corrosion inhibitor. Explain with reference?

12.   Revise Fig. 3 for quality and the same goes for Fig. 4, 6, 8

13.   It is suggested to use consistent captioning, Fig. or Figure? Throughout the manuscript.

14.   Why the table and images captions are described in bold format. Revise, please.

15.   It is suggested to merge the methodology into one or 2 sections and remove the redundant information.

16.   All the Figures, tables, and text should be as per the journal guidelines.

17.   Improve the language used in the article.

18.   All the captions should be checked for uniformity.  

19.   It is suggested to merge the results and discussion into one section to remove redundant information.

20.   The corrosion rate can be investigated using polarization cures which is missing in the current manuscript.

21.   The discussion must be supported by the available literature if there is any.

22.   The author claimed that the dual phase inhibitor performed well due to water repellency without providing any justification or support from the literature. Explain why?

23.   Thorough revision is needed for all sections both technical and non-technical to meet the publication criteria of the journal. 

Author Response

Thank you so much for your detailed review, we appreciate your dedication and effort. Please, find the comments, appreciations and fixes below, in purple color. Please find attached the new version with the principal changes marked in red.

1. The article needs a major revision to improve the flow of contents. Done.
2. The title must be revised in a way that it should be self-explanatory, rather than creating ambiguity. Honestly, the authors consider that the tittle is self-explanatory enough.
3. Please revise the abstract to describe the study and the most important takeaways. Done.

4       Please specify the major findings in the abstract as well. Done.

5. Figure 1 should be referred to if it is from the literature. Done.
6. More literature review is needed in the introduction, the current manuscript (intro) lacks up-to-date literature. Honestly, the authors consider that the literature has been carefully chosen and is quite extensive in the article, so some general improvements have been done.
7. It is suggested not to create a subsection in the introduction unless it is unavoidable. Follow the overall formatting guidelines of the journal. Done.
8. Lines 105 to 135 need revision for describing the research novelty. Done.
9. In suggestion 7, incorporate the literature in a sequential order to develop a conclusive paragraph mentioning the novelty of this study. Improved.
10. Section 2.1 heading needs revision. Done.
11. Dual-phase corrosion inhibitor explanation in section 2.1 must be referred. Done.
12. It has been mentioned that the wash-out would elongate due to a dual-phase corrosion inhibitor. Explain with reference? Done.
13. Revise Fig. 3 for quality and the same goes for Fig. 4, 6, 8 Done.
14. It is suggested to use consistent captioning, Fig. or Figure? Throughout the manuscript. Fixed.
15. Why the table and images captions are described in bold format. Revise, please Fixed.
16. It is suggested to merge the methodology into one or 2 sections and remove the redundant information. Thank you so much. We are trying to explain the onsite procedures  and its methodology.  Both authors reviewed this chapter and no redundant information was found. Please could be more specific with this point?
17. All the Figures, tables, and text should be as per the journal guidelines. Fixed.
18. Improve the language used in the article. Done.
19. All the captions should be checked for uniformity. Done.

20. It is suggested to merge the results and discussion into one section to remove redundant information. Done.

    21. The corrosion rate can be investigated using polarization cures which is missing in the current manuscript. Included new discussion in conclusions as Iscor vs concrete electrical resistance.
    22. The discussion must be supported by the available literature if there is any. Done.
    23. The author claimed that the dual phase inhibitor performed well due to water repellency without providing any justification or support from the literature. New literature has been included. Explain why? The increase of electrical resistivity after DP-SACI application is more than one magnitude order.
    24. Thorough revision is needed for all sections both technical and non-technical to meet the publication criteria of the journal. A mayor technical and non-technical revision have been made.

                                                                                            Best regards,

                                                                                            Diana Martín

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Recommendations were included and now the manuscripts reads much better. Congratulations.

Reviewer 3 Report

Ln 230 Is not "than" but "that"

Check throughout the document (charts included) for the consistency of using comma or dot as a decimal separator.

Reviewer's comments were satisfactorily addressed.