Experimental, Numerical, and Theoretical Studies of Bond Behavior of Reinforced Fly Ash-Based Geopolymer Concrete
Round 1
Reviewer 1 Report
The bonding behavior of reinforced fly ash-based geopolymer concrete were characterized by experimental tests, numerical simulation and theoretical studies in this manuscript. It adds important values to the durable design of reinforced concrete. The research program was well planned and the research findings were presented and discussed properly. Therefore, it can be accepted for publication after carrying on minor revision. Here are some recommendations for improvement:
1) Figure 1 is too complicated for reading. Please make it concise by deleting not necessary pictures.
2) Figure 3 (a) is the same as the one in Figure 2.
3) Figure 3 is enough to explain the mesh of used simulation mode. Figure 4 can be therefore deleted.
4) the materials parameters for defining the interface should be provided in Section 3.3.
5) The failure mode study was too weak. Please add the test results to conclude what’s the relation between specimen conditions, testing conditions and failure modes?
Author Response
Response to Reviewer 1 Comments
The bonding behavior of reinforced fly ash-based geopolymer concrete were characterized by experimental tests, numerical simulation and theoretical studies in this manuscript. It adds important values to the durable design of reinforced concrete. The research program was well planned and the research findings were presented and discussed properly. Therefore, it can be accepted for publication after carrying on minor revision. Here are some recommendations for improvement:
First, we would like to sincerely thank you for your concern and deeply appreciate your highest efforts in dealing with our paper for peer-review process. Your comments are greatly valuable and helpful for our revision and improvement. We have carefully studied these very thorough guides and made the corresponding revisions based on your suggestion.
Point 1. Figure 1 is too complicated for reading. Please make it concise by deleting not necessary pictures.
Response 1: Thank you for your suggestion, Figure 1 is simplified for easy for reading.
Point 2. Figure 3 (a) is the same as the one in Figure 2.
Response 2: Thank you for your comment, Figure 2 is edited again.
Point 3 Figure 3 is enough to explain the mesh of used simulation mode. Figure 4 can be therefore deleted.
Response 3: Thank you for your recommendation, the authors would like to keep Figure 4. In this Figure, the authors show the details of modelling such: whole specimens, concrete and steel bar.
Point 4. The materials parameters for defining the interface should be provided in Section 3.3.
Response 4: Thank you for your suggestion. The parameters used to define the properties of the contact modelling in Abaqus are determined via regression analysis of experimental results. Two formulas are then proposed to predict the maximum shear stress τmax and the corresponding value of slip s1 at which τmax develops. Explanation for this concern is added and highlighted on page 9 of the revised manuscript.
Point 5. The failure mode study was too weak. Please add the test results to conclude what’s the relation between specimen conditions, testing conditions and failure modes?
Response 5: Thank you for your comment. Additional discussions on the failure of test specimens were added and highlighted on page 16 of the revised manuscript.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The authors performed experimental work to study the bond behavior in geopolymer concrete. Although the topic is interesting, major revision is necessary regarding some concerns, as follows:
- Table 2: Please explain the importance of curing conditions (temperature) for geopolymer concrete in the introduction.
- Fig. 2: Please mention the loading rate of the pull-out test.
- Table 3: Why did constant value considered for the embedded length (ld). Commonly, the value of 5 times the rebar diameter has been considered by researchers to have a constant value for the ratio of ld/db. This problem significantly affects the results and some conflicting results can be obtained due to ignoring this point.
- Fig. 7: the reviewer recommends comparing your results with the normal concrete.
- Usually, higher rebar diameters result in low bonds. However, conflicting results were reported by the authors. Please find some literature to confirm your findings.
- Please mention the rib height and rib spacing of all rebars (different diameters) in the manuscript. This parameter is crucial for bond strength.
- Fig. 9: why only two bond models were selected by the authors? Different reliable models were presented by different researchers which should be mentioned by the authors. The reviewer recommends reading the following papers to consider more models:
[-] Wu, Y. F., & Zhao, X. M. (2013). Unified bond stress–slip model for reinforced concrete. Journal of Structural Engineering, 139(11), 1951-1962.
[-] Mousavi, S. S., Dehestani, M., & Mousavi, K. K. (2017). Bond strength and development length of steel bar in unconfined self-consolidating concrete. Engineering Structures, 131, 587-598.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors improved the manuscript structure.
