Effect of SIFRCCs with Varying Steel Fiber Volume Fractions on Flexural Behavior
Round 1
Reviewer 1 Report
This study conducted flexural testing to investigate the mechanical properties of a high-performance fiber-reinforced cementitious composite. The material contains different amounts of steel fibers. This paper reports some useful experimental data. The paper can be improved by adding more contents as detailed as follows.
1. A more thorough introduction should be provided to specify the technical contributions of this study. More recent related studies can be reviewed and emphasize your original work in the field.
2. More experimental results should be added to enhance the quality of this study. Currently, you only report the bending experiment and results. Please add more tests and results. For example, what about the flowability of the material after you add different amounts of steel fibers? How about the compressive strength?
3. More in-depth analysis and discussions should be added. For example, what are the mechanisms of the effect of steel fibers? How is your material different from the existing materials? And explain why.
4. How does the addition of steel fibers affect the cost? It is good to provide your insights into financial aspects of the presented material.
5. How many specimens did you test for duplication at each steel fiber content? How about the deviation of different specimens?
6. Check the reference list and remove unnecessary papers from the list.
Author Response
Response to Reviewer 1 Comments
This study conducted flexural testing to investigate the mechanical properties of a high-performance fiber-reinforced cementitious composite. The material contains different amounts of steel fibers. This paper reports some useful experimental data. The paper can be improved by adding more contents as detailed as follows.
Point 1:
A more thorough introduction should be provided to specify the technical contributions of this study. More recent related studies can be reviewed and emphasize your original work in the field
Response 1:
Thank you for your comments.
Introduction part had been updated.
Point 2:
More experimental results should be added to enhance the quality of this study. Currently, you only report the bending experiment and results. Please add more tests and results. For example, what about the flowability of the material after you add different amounts of steel fibers? How about the compressive strength?.
Response 2:
Thank you for your comments.
Compressive and tensile strength results had been added.
First, the prismatic mold of 100 × 100 × 350 mm was filled with steel fibre with respect to volume fraction. Then, Slurry, as prepared after mixing the contents, was poured until no more bubbles were seen to ensure the infiltration of slurry into the fibres. Slurry act as a liquid so unable to measure flowability.
Point 3:
More in-depth analysis and discussions should be added. For example, what are the mechanisms of the effect of steel fibers? How is your material different from the existing materials? And explain why.
Response 3:
Thank you for your comments.
The fiber-reinforced concrete specimens even with low fiber volume fraction retained post-cracking ability to carry out loads. The HPFRCCs have been developed to improve the mechanical performance, resilience and durability of concrete structures. The fiber-reinforced concrete is being popular due to its greater impact resistance properties.
Other researchers did not conduct many experiments on SIFRCCs. Therefore, it is difficult to comparisons with other studies under similar conditions. I will find and review comparable literature such as HPFRCCs and UHPC by other researchers.
Point 4:
How does the addition of steel fibers affect the cost? It is good to provide your insights into financial aspects of the presented material.
Response 4:
Thank you for your comments.
On increasing the amount of steel fiber will increase the construction cost. These materials are design to resist impact load, explosion and fire resistance. Such materials can be used to construct public infrastructures examples public hospitals, military buildings, schools etc.
Point 5:
How many specimens did you test for duplication at each steel fiber content? How about the deviation of different specimens?
Response 5:
Thank you for your comments.
Ten specimens of each variable were tested. Standard deviations of 4%, 5%, and 6% for fiber volume fraction were 2.12, 1.46 and 3.55, respectively.
Point 6:
Check the reference list and remove unnecessary papers from the list.
Response 6:
Thank you for your comments.
References had been updated.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper studies the flexural behaviors of a high-performance fiber-reinforced cementitious composite (HPFRCC) through experiments. The topic is interesting and important. This study presents some original data that might be useful for future research and applications. I have some suggestions that might help further improve the quality of the paper:
(1) In the introduction section, it is better to add more detailed information of existing studies on HPFRCC, giving readers a clearer picture of the background and the state-of-the-art. In recent years, there are many studies on HPFRCC materials and structural applications. Please cite more papers and clarify the novelty of this study. Here are two examples, one on material and one on structural application: Khayat et al. 2019. Rheological properties of ultra-high-performance concrete—An overview. Cement and Concrete Research, 124, p.105828. Li et al. 2019. Post-fire seismic behavior of two-bay two-story frames with high-performance fiber-reinforced cementitious composite joints. Engineering Structures, 183, pp.150-159.
(2) While it is important to present the flexural testing results, it is essential to report the fresh properties and compressive strength of the materials. Please add the testing method and results of flowability and compressive strength.
(3) The photo in Fig. 1 is not very clear. Please consider replacing it with a better photo. Also, please add a drawing of the specimen and the test set-up for the bending test.
(4) Please justify the use of "high-performance" in the name of the material. Which are the properties that indicate high performance? Does the material have high flowability, strength, and/or long-term durability? Please elaborate.
(5) The amount of steel fibers is high, so I am interested to know how the addition of steel fibers affects the fresh properties such as the flowability and fiber dispersion. The addition of steel fibers tends to increase the viscosity and thus reduce the flowability, and, subsequently, the change of viscosity affects the fiber dispersion. Please check paper on rheology control for UHPC, and add a discussion in your paper.
(6) You have much self-citation. In the 17 referred papers, it seems you include 10 of your own papers. Are all your own papers necessary in this paper? It is good to have a more diverse resource of references from different independent groups.
Author Response
Response to Reviewer 2 Comments
This paper studies the flexural behaviors of a high-performance fiber-reinforced cementitious composite (HPFRCC) through experiments. The topic is interesting and important. This study presents some original data that might be useful for future research and applications. I have some suggestions that might help further improve the quality of the paper:
Response:
Thank you for your comments.
Point 1:
In the introduction section, it is better to add more detailed information of existing studies on HPFRCC, giving readers a clearer picture of the background and the state-of-the-art. In recent years, there are many studies on HPFRCC materials and structural applications. Please cite more papers and clarify the novelty of this study. Here are two examples, one on material and one on structural application: Khayat et al. 2019. Rheological properties of ultra-high-performance concrete—An overview. Cement and Concrete Research, 124, p.105828. Li et al. 2019. Post-fire seismic behavior of two-bay two-story frames with high-performance fiber-reinforced cementitious composite joints. Engineering Structures, 183, pp.150-159.
Response 1:
Thank you for your comments.
Introduction section had been updated and references had been updated.
Point 2:
While it is important to present the flexural testing results, it is essential to report the fresh properties and compressive strength of the materials. Please add the testing method and results of flowability and compressive strength.
Response 2:
Thank you for your comments.
Compressive and tensile strength had been added and preparation method of slurry had been added.
First, the prismatic mold of 100 × 100 × 350 mm was filled with steel fibre with respect to volume fraction. Then, Slurry, as prepared after mixing the contents, was poured until no more bubbles were seen to ensure the infiltration of slurry into the fibres. Slurry act as a liquid so unable to measure flowability.
Point 3:
The photo in Fig. 1 is not very clear. Please consider replacing it with a better photo. Also, please add a drawing of the specimen and the test set-up for the bending test.
Response 3:
Thank you for your comments.
Figure 1 had been changed and required figure had been added.
Point 4:
Please justify the use of "high-performance" in the name of the material. Which are the properties that indicate high performance? Does the material have high flowability, strength, and/or long-term durability? Please elaborate.
Response 4:
Thank you for your comments.
From this experiment strength is high and durability test is in under process.
Point 5:
The amount of steel fibers is high, so I am interested to know how the addition of steel fibers affects the fresh properties such as the flowability and fiber dispersion. The addition of steel fibers tends to increase the viscosity and thus reduce the flowability, and, subsequently, the change of viscosity affects the fiber dispersion. Please check paper on rheology control for UHPC, and add a discussion in your paper.
Response 5:
Thank you for your comments.
Fiber dispersion is random and first the fiber is placed in advance in specimen then poured prepared slurry to manufacture the specimen.
Point 6:
You have much self-citation. In the 17 referred papers, it seems you include 10 of your own papers. Are all your own papers necessary in this paper? It is good to have a more diverse resource of references from different independent groups. .
Response 6:
Thank you for your comments.
Reference had been updated.
Author Response File: Author Response.pdf
Reviewer 3 Report
Introduction:
- What are the maximum fibre contents that can be realized using slurry-infiltration?
- How is the "desirable flexural strength" defined/deduced?
- Is there a definition for the term "high fibre volume fraction"?
- Advantages of the manufacturing technology should be further specified (optimized fibre orientation, no agglomeration...)
- In what cases is this technology already applied?
Experiments:
- Regarding the potential of the fibre addition it would be nice to have a reference value for pure concrete
- Table 4 is very confusing: If You differentiate between cement content and binder, does that mean that binder includes the silica fume?
- Formula for energy absorption capacity based on ASTM C 1609 is missing.
- Was the fracture of the fibres / the pull out of the fibres visually observed? If yes, this has to be stated and in the ideal case could be illustrated by a picture.
Can You differentiate between the flexural strength at the point where the cementitious matrix breaks and the maximum flexural strength? When comparing figures 2 to 4 , figure 3 seems to fall out of line...
Analysis / Conclusion:
- How do Your results relate to the findings of others?
- The results seem not surprising....
General:
- There are many repetitions in the text. It could be much more concise and shorter.
- Please find a native speaker to correct all the language mistakes.
Good luck!
Author Response
Response to Reviewer 3 Comments
Introduction:
Point 1:
What are the maximum fibre contents that can be realized using slurry-infiltration?
Response 1:
Thank you for your comments.
Till now 8% of steel fiber had been done in lab test and 6% is in mock-up test.
Point 2:
How is the "desirable flexural strength" defined/deduced?
Response 2:
Thank you for your comments.
Generally, flexural strength is about one-sixth of the compressive strength for conventional concrete. And from this experiment results at 6% steel fiber volume fraction, the flexural strength is about a half of compressive strength. Which is good materials in terms of mechanical strength. So, according to experimental results this material has a desirable flexural strength.
Point 3:
Is there a definition for the term "high fibre volume fraction"?
Response 3:
Thank you for your comments.
Other researchers used less percentage of steel fiber such as in fiber-reinforced concrete experiment maximum used steel fiber is 2% and in this experiment 6% steel fiber was used. So, the term, high volume fraction, was used.
Point 4:
Advantages of the manufacturing technology should be further specified (optimized fibre orientation, no agglomeration...
Response 4:
Thank you for your comments.
The steel fiber orientation is random. First, the prismatic mold of 100 × 100 × 350 mm was filled with steel fibre with respect to volume fraction. Then, Slurry, as prepared after mixing the contents, was poured until no more bubbles were seen to ensure the infiltration of slurry into the fibres. Slurry act as a liquid so unable to measure flowability.
Point 5:
In what cases is this technology already applied?
Response 5:
Thank you for your comments.
Mock-up test had been complete by construct building structures for explosion test. This experiment is not applied in practice.
Point 6:
Regarding the potential of the fibre addition it would be nice to have a reference value for pure concrete.
Response 6:
Thank you for your comments.
For pure concrete the flexural strength is low but we will do experiment in future.
Point 7:
Table 4 is very confusing: If You differentiate between cement content and binder, does that mean that binder includes the silica fume?
Response 7:
Thank you for your comments.
Yes, binder includes the silica fume. Table 4 had been changed in simple form.
Point 8:
Formula for energy absorption capacity based on ASTM C 1609 is missing.
Response 8:
Thank you for your comments. It is already presented in 2.3 Experimental method.
To evaluate the energy absorption capacity according to the fibre mixing rate, the specimen toughness presented in ASTM C1609 was calculated, but due to the bending behavior characteristics of the SIFRCC considered in this study, the load-deflection curve presented in ASTM C1609 was not suitable to calculate total area under the load- deflection curve up to a net deflection of 1/150 of the span Length. Thus, to compare the energy absorption capacity according to the fibre content, the toughness characteristics of the specimens were compared by substituting the total area under the load-deflection curve up to net deflection of 20 mm.
Point 9:
Was the fracture of the fibres / the pull out of the fibres visually observed? If yes, this has to be stated and in the ideal case could be illustrated by a picture.
Response 9:
Thank you for your comments.
I’m sorry, I have similar type of the picture as shown as below. Can I add this picture in manuscript?
Point 10:
Can You differentiate between the flexural strength at the point where the cementitious matrix breaks and the maximum flexural strength? When comparing figures 2 to 4 , figure 3 seems to fall out of line...
Response 10:
Thank you for your comments.
The actual break of the cement matrix occurred inside the test specimen, which was confirmed by visual during an experiment, that the cement matrix falling from specimen. The bending of the specimen due to the high fibre mixing rate caused the fracture of the matrix due to adhesion failure between the steel fibre and the cement matrix. So unable to differentiate between the flexural strength at the point where the cementitious matrix breaks and maximum flexural strength.
Point 11:
How do Your results relate to the findings of others?
Response 11:
Thank you for your comments.
Generally, flexural strength is about one-sixth of the compressive strength for conventional concrete. And from this experiment results at 6% steel fiber volume fraction, the flexural strength is about a half of compressive strength.
Point 12:
The results seem not surprising....
Response 12:
Thank you for your comments.
Other researchers did not conduct many experiments on SIFRCCs. Therefore, it is difficult to comparisons with other studies under similar conditions. I will find and review comparable literature such as HPFRCCs and UHPC by other researchers.
Point 13:
There are many repetitions in the text. It could be much more concise and shorter.
Response 13:
Thank you for your comments.
Text had been updated.
Point 14:
Please find a native speaker to correct all the language mistakes
Response 14:
Thank you for your comments.
Paper had been corrected from “Editage, a brand of Cactus Communication” and certificate of English Editing is attached.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The introduction and results discussion need to be further improved. Please justify why SIFRCC can be considered as ultra-high performance concrete.
Author Response
Response to Reviewer 1 Comments
Point 1:
The introduction and results discussion need to be further improved. Please justify why SIFRCC can be considered as ultra-high performance concrete.
Response 1:
Thank you for your comments.
The introduction and results discussion section had been updated.
Both SIFRCCs and UHPC can be considered as a type of HPFRCC. SIFRCCs also have better ductility and energy absorption because of its high fiber volume fraction than UHPC.
Author Response File: Author Response.pdf
