Impact of Interfacial Transition Zone on Concrete Mechanical Properties: A Comparative Analysis of Multiphase Inclusion Theory and Numerical Simulations
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis manuscript presents an important exploration into the properties and applications of recycled concrete (RC) by using combination of multiphase inclusion theory and finite element numerical simulation. Several comments need to be addressed :
1. The introduction could benefit significantly from incorporating recent advancements in materials science that can enhance the properties of RC.
2. Please add future development or future prospect sub-chapter (can be writen before conclusion section). I recommend discussing the potential integration of bacterial cellulose within the composite structure of RC. Bacterial cellulose has been recognized for its exceptional tensile strength and biodegradability, attributes that could be particularly beneficial in reinforcing the interface transition zones (ITZs), which are traditionally considered weak links in concrete. By integrating bacterial cellulose, not only could the mechanical properties and durability of RC be improved, but such addition would also align with the environmental sustainability goals highlighted in the manuscript. Including this aspect would provide a more futuristic perspective and align the discussion with cutting-edge research in the field. I recommend to add this most udpated article for the reference (https://doi.org/10.1080/15440478.2023.2301386)
3. Line 331. Please check the sentence, hard to understand.
Author Response
Response to reviewer1
Thank you for your valuable feedback on this manuscript. The original text is supplemented as follows.
- The introduction could benefit significantly from incorporating recent advancements in materials science that can enhance the properties of RC.
Answer: Thanks for your comments. The manuscript has been revised by adding more recent references. “Some scholars enhance the mechanical properties of ITZ in recycled concrete by adding fiber materials or nano-scale materials into RC [6] [7] [8], and it is beneficial to study the specific changes of ITZs in a cross-scale way.”
- Please add future development or future prospect sub-chapter (can be written before conclusion section). I recommend discussing the potential integration of bacterial cellulose within the composite structure of RC. Bacterial cellulose has been recognized for its exceptional tensile strength and biodegradability, attributes that could be particularly beneficial in reinforcing the interface transition zones (ITZs), which are traditionally considered weak links in concrete. By integrating bacterial cellulose, not only could the mechanical properties and durability of RC be improved, but such addition would also align with the environmental sustainability goals highlighted in the manuscript. Including this aspect would provide a more futuristic perspective and align the discussion with cutting-edge research in the field. I recommend to add this most updated article for the reference (https://doi.org/10.1080/15440478.2023.2301386)
Answer: Thank you for your suggestion. The following paragraph is added to the conclusion,
“Additionally, methods to enhance the strength of ITZ through the use of nanoscale materials continue to emerge in the future, and relying solely on microscopic experiments is not enough to fully demonstrate the macroscopic mechanical properties of materials, ongoing research on multiphase inclusion theory is expected to guide the selection of concrete materials and the optimization of ITZ layers in practical applications, enhancing the utilization efficiency of recycled materials in concrete.”
- Line 331. Please check the sentence, hard to understand.
Answer: Thank you for your comments. We changed the sentence to “In this study, only one of OITZ or NITZ is changed to analyze the influence of its thickness on the overall mechanical properties.”
Reviewer 2 Report
Comments and Suggestions for AuthorsIt is very interesting research papers. Before publishing research papers, I have several questions below.
1. Introduction:
- What gaps exist in current research on ITZ and recycled concrete that can be addressed through multiphase inclusion theory?
2. Theoretical Model of Multiphase Inclusions:
- How does Eshelby's theory contribute to understanding the behavior of inclusions within composite materials?
3. Numerical Simulation:
- What specific parameters and variables are considered in the numerical simulations of multiphase inclusions? Please insert Table to improve understating for future readers.
4. Discussion:
- How do the theoretical results of multiphase inclusions compare to the numerical simulations in terms of predicting the mechanical properties of recycled concrete?
- What insights can be gained from analyzing the influence of different types of ITZs on the overall structural mechanical properties of recycled concrete in terms of practical implications?
5. Conclusion:
- What are the key contributions and limitations of applying the multiphase inclusion theory to analyze the impact of ITZs on recycled concrete?
- What future research directions or applications can be explored based on the results and insights obtained from this study on multiphase inclusions in recycled concrete?
Comments on the Quality of English LanguageNA
Author Response
Response to reviewer2
Thank you for your valuable feedback on this manuscript. The original text is supplemented as follows.
- Introduction:
- What gaps exist in current research on ITZ and recycled concrete that can be addressed through multiphase inclusion theory?
Answer: Thanks for your comments. The manuscript has been revised by adding the following sentences in the introduction part: “The multiphase inclusion theory can address these gaps by providing a theoretical framework that incorporates the heterogeneity and multiphase nature of RC. It allows for a detailed analysis of the interactions between different phases, enabling more precise predictions of mechanical properties and enhancing our understanding of how ITZ characteristics influence the overall behavior of RC. This theoretical approach can also help to bridge the gap between macroscopic observations and microscopic interactions, providing insights that are difficult to obtain through empirical methods alone.”
- Theoretical Model of Multiphase Inclusions:
- How does Eshelby's theory contribute to understanding the behavior of inclusions within composite materials?
Answer: Thanks for your comments. The manuscript has been revised by adding the following sentences in section 2: “ Eshelby's theory is fundamental in understanding the elastic behavior of inclusions within a composite material. The theory describes how an inclusion, embedded in an infinite elastic matrix, affects the surrounding stress and strain fields. By solving for the Eshelby tensor, which depends on the shape and material properties of the inclusion and the matrix, it is possible to predict the stress distribution within the inclusion and the matrix. In the context of recycled concrete, Eshelby's theory helps model the ITZs as inclusions with distinct mechanical properties compared to the surrounding mortar and aggregate. This approach allows for the assessment of how different ITZs influence the overall mechanical properties of RC.”
3. Numerical Simulation:
- What specific parameters and variables are considered in the numerical simulations of multiphase inclusions? Please insert Table to improve understating for future readers.
Answer: Thanks for your comments. The manuscript has been revised by adding Table 2. Physical properties of various phase materials in ABAQUS in section 3.
- Discussion:
- How do the theoretical results of multiphase inclusions compare to the numerical simulations in terms of predicting the mechanical properties of recycled concrete?
Answer: Thanks for your comments. The manuscript has been revised in section 4. “Although the error is indeed within a small range after calculation, it can be seen from Figures 10(a) to 10(c) that the trends of change in elastic modulus and Poisson's ratio are relatively consistent. When the ITZ Poisson's ratio is reduced, the error rate remains steady between 6% to 7%. Figure 10(d) is influenced by theoretical calculations, where minor variations in shear modulus and bulk modulus affect the trend of Poisson's ratio changes. In fact, for the structure as a whole, minor fluctuations in Poisson's ratio have a negligible impact on its mechanical properties. Additionally, it can be observed that the values calculated theoretically are always slightly higher than those obtained from numerical simulations, which may stem from inconsistencies in calculation accuracy, and the isotropic nature of materials in the finite element analysis. With displacement loading, the displacement between phases can generally achieve complete synergy. From the trend of the final prediction, the prediction results obtained by using the multiphase inclusion theory are more accurate than those obtained by using the finite element method in the elastic stage. During the elastic stage, the overall deformation trend of the specimen in the simulation is relatively stable. In the theory of multiphase inclusions, the weakening of the overall mechanical properties of ITZ is considered, as shown in Section 2. The theory accounts for the heterogeneity and complex interactions between different phases, including the ITZs, which are often challenging to model accurately through empirical methods alone.”
- What insights can be gained from analyzing the influence of different types of ITZs on the overall structural mechanical properties of recycled concrete in terms of practical implications?
Answer: Thanks for your comments. The conclusion has been revised by adding: “Based on the comparison of different ITZs in theory, it is suggested that the old mortar attached on RA should be removed as much as possible in practical application. In this way, the existence of OITZ is reduced to enhance the mechanical properties of RC.”
- Conclusion:
- What are the key contributions and limitations of applying the multiphase inclusion theory to analyze the impact of ITZs on recycled concrete?
Answer: Thanks for your comments. The conclusion has been revised by adding: “The multiphase inclusion theory provides a detailed and accurate framework for predicting and optimizing the mechanical properties of recycled concrete. Although it has great potential for further computational research, it is clear that its updating requires complex models and hypotheses, as well as experimental verification of them.”
- What future research directions or applications can be explored based on the results and insights obtained from this study on multiphase inclusions in recycled concrete?
Answer: Thanks for your comments. The conclusion has been revised: “Additionally, methods to enhance the strength of ITZ through the use of nanoscale materials continue to emerge in the future, and relying solely on microscopic experiments is not enough to fully demonstrate the macroscopic mechanical properties of materials, ongoing research on multiphase inclusion theory is expected to guide the selection of concrete materials and the optimization of ITZ layers in practical applications, enhancing the utilization efficiency of recycled materials in concrete.”
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript have been improved. I have no further comments.
