Experimental Analysis of Creep and Shrinkage of Self-Compacting Concrete with Recycled Concrete Aggregates

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Please correct:

table 4: standard deviation of temperature (+ and - in brackets are missing)

line 595: significant (with "t" not "d")

comments:

1) what is the tempreature of concrete mix measured for? The data is placed in tbale 4, but it is not explained in the text why you did this, and what is the impact of temp. of concrete mix on the properties whish were investigated

2) how can you explain/compare the shrinkage strain of SCC10 and SCC20 (figure 8). SCC10 has got less RCA and its shirnkage strain is higher than that of SCC20, although the general conclusion was that shrinkage is higher in the specimens with higher amount of RCA.

3) please explain the last conclusion (lines 600-602): it seems that compressive strenght of specimens was three times lower after 2 days of maturing and 2 times lower after 28d of maturing.

 

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study investigates the impact of using recycled concrete aggregates (RCA) in self-compacting concrete (SCC). The study explores how different proportions of RCA affect the mechanical properties, shrinkage, and creep of SCC. The experimental analysis involves multiple concrete mixtures, evaluating compressive strength, Young’s modulus, and long-term deformation characteristics. The findings suggest that increasing RCA content proportionally increases shrinkage strain and that creep deformation correlates more strongly with concrete density than with compressive strength. The work is well-structured and provides valuable insights into the sustainable use of RCA in SCC. However, there are some areas where improvements are needed, including clarity in the presentation of results, deeper discussion on practical implications, and refinement of data interpretation.

The abstract should explicitly state the key numerical findings to give readers a clearer understanding of the results.

There is a lack of discussion on the limitations of using RCA in SCC. A section on challenges or drawbacks should be included.

The water absorption properties of RCA should be explicitly compared to natural aggregates to highlight differences in mix behavior.

A sensitivity analysis discussing how variations in RCA quality could affect results would strengthen the study.

The correlation between concrete density and creep should be explained in more depth, why is density a more relevant parameter than compressive strength?

The potential structural applications of SCC with RCA should be mentioned, does it perform well enough for use in high-performance concrete?

The manuscript should clarify whether the shrinkage and creep data can be generalized to other mix designs or if the findings are specific to the studied compositions.

The practical implications of the findings should be elaborated on, especially in terms of structural applications and industry standards.

To strengthen the literature review and identify the research gap and significance of the current study, the following recent studies should be included in the revised manuscript.

https://doi.org/10.1016/j.istruc.2025.108558

https://doi.org/10.1680/jadcr.23.00205

Comments on the Quality of English Language

 The English could be improved to more clearly express the research.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This paper focuses on the application of Recycled Concrete Aggregate (RCA) in Self-Compacting Concrete (SCC), with multiple innovative aspects. The creep test was carried out by loading specimens at the age of 2 days to simulate the prestressing process in precast prestressed concrete elements, providing unique data for the calibration and verification of relevant models. The research investigated the replacement of dolomite aggregates with RCA, comprehensively analyzing the properties of fresh and hardened concrete, including workability, mechanical properties, shrinkage, and creep deformation by comparing multiple concrete mix ratios with different replacement ratios and the addition of fly ash or not. This offers a systematic and comprehensive perspective. Moreover, the creep deformation of concrete was analyzed by introducing the creep coefficient and compliance function, revealing the internal laws of the influence of RCA on the long - term performance of concrete, and providing theoretical support and data reference for the wide application of RCA in the construction industry.

Minor Revision Suggestions

1 Some charts lack clear annotations for the meanings of curves and data points, such as shrinkage strain and total strain curves. It is recommended to elaborate on the concrete mix ratios represented by each curve in the figure caption and annotate key data points for easier understanding of the performance change trends of different mix ratios.

2 The discussion of some data results is insufficient when analyzing the influencing factors of concrete performance. For the difference in creep strain between SCC50 and SCC40 mixtures, further analysis could be conducted in combination with microstructures, such as exploring the impacts of aggregate gradation and pore structure on creep performance to enrich the discussion.

3 Inconsistent expressions of some terms exist in the article. For example, "elastic modulus" is sometimes referred to as "Young's modulus". It is advisable to unify the terms, using either "elastic modulus" or "Young's modulus" throughout to enhance the professionalism and standardization of the article.

4 When introducing the curing conditions of specimens, the potential impact of humidity changes in the curing environment on the experimental results is not mentioned. It is recommended to supplement the humidity change range and its possible impact analysis to make the description of experimental methods more complete.

5 There are some format inconsistencies in the reference section. For example, the abbreviation methods of some authors' names vary. It is suggested to standardize the reference format and typeset the author names, journal names, volume numbers, page numbers, etc. in accordance with the journal requirements.

6 Repetitive expressions can be found in some paragraphs. For instance, the same influencing factors are repeatedly mentioned when discussing the impact of RCA on concrete performance. It is recommended to streamline the text, avoid redundant discussions, and improve the readability of the article.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for sharing the revised manuscript. The authors incorporated all my comments, and the manuscript is now sufficiently improved. Hence, I recommend publishing the manuscript in Applied Sciences.

Comments on the Quality of English Language

The English could be improved to express the research more clearly.