Behavior of Ultra-High-Performance Concrete with Hybrid Synthetic Fiber Waste Exposed to Elevated Temperatures
, Marijana Hadzima-Nyarko 2,3, Magdy Youssef Riad Riad 4 and Radwa Defalla Abdel Hafez 5Round 1
Reviewer 1 Report
This study carried out a lot of experiments on UHPC containing waste synthetic fibers with or without high temperature exposure and some interesting results were obtained. Before acceptance, the following comments should be fully addressed.
1) The authors said that hybrid synthetic waste fibers contained different types and different length fibers. How about the ratios?
2) Only one addition 1% was adopted to fiber content. Why did the authors select this level? please explain.
3) There are many pictures for normal testing apparatuses such as from Fig. 2 to Fig. 8. They cannot provide any meaningful information, please delete.
4) Table 3, 4, 5, 6 and 7 can be deleted because these data have been presented in figures.
5) Highlights and conclusions should be significantly refined. Only new findings should be clearly presented.
Author Response
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Reviewer #1: |
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General comments: |
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No. |
Reviewer Comments |
Response |
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1 |
The authors said that hybrid synthetic waste fibers contained different types and different length fibers. How about the ratios?
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We responded to this comment, Equal proportions of all types |
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2 |
Only one addition 1% was adopted to fiber content. Why did the authors select this level? please explain. |
We responded to this comment, This was based on previous studies and empirical tests |
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3 |
There are many pictures for normal testing apparatuses such as from Fig. 2 to Fig. 8. They cannot provide any meaningful information, please delete. |
We responded to this comment, Pictures have been deleted |
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4 |
Table 3, 4, 5, 6 and 7 can be deleted because these data have been presented in figures. |
We responded to this comment, Tables have been deleted |
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5 |
Highlights and conclusions should be significantly refined. Only new findings should be clearly presented. |
We responded to this comment, Important highlights and conclusions have been reviewed. |
Reviewer 2 Report
This Paper presents an experimental study to investigate effects of hybrid synthetic waste fibers, elevated temperature, and exposure time on the Ultra-high-performance concrete (UHPC). This work is interesting and gives many interested results such as the reduction of cracks in the concrete reinforced with hybrid synthetic waste fibers and others. However, Authors should enhance the literature review adding the research work carried by Ye Li et al. (2002) on the flexural behavior of ultra-high performance hybrid fiber reinforced concrete at the ambient and elevated temperature. Furthermore, to enhance the quality of the manuscript, some suggestions are drawn as follows:
1- For figure1: (a), (b), (c) notations should be indicated on the images.
2- Add the research work carried out by Ye Li et al. (2002) to the literature review.
Reference: Ye Li, En-HuaYang, Kang HaiTan, Flexural behavior of ultra-high performance hybrid fiber reinforced concrete at the ambient and elevated temperature. Construction and Building Materials, 2020. 250(11): 118487. DOI:10.1016/j.conbuildmat.2020.118487
Also, the research work of Piotr Smarzewski and Danuta Barnat-Hunek (2017)
Reference: Piotr Smarzewski and Danuta Barnat-Hunek, Effect of Fiber Hybridization on Durability Related Properties of Ultra-High Performance Concrete. International Journal of Concrete Structures and Materials, 2017. 11:315–325. https://doi.org/10.1007/s40069-017-0195-6
These references should be cited in the references list.
3- Page 4, line 151: Delete this word “including”.
In line 154: Correct the sentence “the UHPC specimens were tested”
4- Why it is chosen these 3 fiber types: Nylon, polyester and polypropylene and not steel fibers?
5- All standards used should be cited in the reference list such as ASTM (C597, C518, C78, C192) and ACI committee 544.
6- Section 3.1 “specimen description” is not clear at all and should be rewritten. The procedure should be clearly described from the concrete cast step to the testing step (after 91 days).
6- What about the durability of this developed material to freeze – thaw cycles and to sulfate effects.
7- There is a certain contradictory in the thermal conductivity. It is said (in page 11, line410) that the thermal conductivity of UHPC is very low because of the low pores in concrete; however, in page 12-line422, it is said that the thermal conductivity decreases during heating due to an increase in overall porosity. How to explain this contradictory?
8- Correct the temperature unit in the title of Figure 21 and 22.
9- Page 19, line 676: Correct the sentence in this line “…were decreased to 7.49%, 5.04 %, and 1.74 %, respectively”
10- Figures 21, 22, 25, 26: Curves in these figures should be redrawn.
11- Page 21, line 763: What is the difference between the number of impacts required to fracture and the number of blows required to fail?
Comments for author File: 
Comments.pdf
Author Response
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Reviewer #2: |
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General comments: |
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No. |
Reviewer Comments |
Response |
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1 |
For figure1: (a), (b), (c) notations should be indicated on the images.
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We responded to this comment, Pictures have been modified |
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2 |
Add the research work carried out by Ye Li et al. (2002) to the literature review.
Reference: Ye Li, En-HuaYang, Kang HaiTan, Flexural behavior of ultra-high performance hybrid fiber reinforced concrete at the ambient and elevated temperature. Construction and Building Materials, 2020. 250(11): 118487. DOI:10.1016/j.conbuildmat.2020.118487
Also, the research work of Piotr Smarzewski and Danuta Barnat-Hunek (2017)
Reference: Piotr Smarzewski and Danuta Barnat-Hunek, Effect of Fiber Hybridization on Durability Related Properties of Ultra-High Performance Concrete. International Journal of Concrete Structures and Materials, 2017. 11:315–325. https://doi.org/10.1007/s40069-017-0195-6
These references should be cited in the references list.
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We responded to this comment, References have been added to the paper |
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3 |
Page 4, line 151: Delete this word “including”.
In line 154: Correct the sentence “the UHPC specimens were tested”
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We responded to this comment, Required modifications have been made |
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4 |
Why it is chosen these 3 fiber types: Nylon, polyester and polypropylene and not steel fibers?
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We responded to this comment, Steel fibers have been studied by many, and new types must be chosen |
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All standards used should be cited in the reference list such as ASTM (C597, C518, C78, C192) and ACI committee 544.
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We responded to this comment, References have been added |
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6 |
Section 3.1 “specimen description” is not clear at all and should be rewritten. The procedure should be clearly described from the concrete cast step to the testing step (after 91 days).
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We responded to this comment, This part has been rewritten |
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7 |
What about the durability of this developed material to freeze – thaw cycles and to sulfate effects.
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These tests will be studied in the second part of this research. |
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8 |
There is a certain contradictory in the thermal conductivity. It is said (in page 11, line410) that the thermal conductivity of UHPC is very low because of the low pores in concrete; however, in page 12-line422, it is said that the thermal conductivity decreases during heating due to an increase in overall porosity. How to explain this contradictory?
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Because hybrid synthetic fiber wastes filled the pores and prevented a high thermal conductivity value. Thermal conductivity decreases with the presence of fibers. |
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9 |
Correct the temperature unit in the title of Figure 21 and 22.
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We responded to this comment, Icons have been modified |
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10 |
Page 19, line 676: Correct the sentence in this line “…were decreased to 7.49%, 5.04 %, and 1.74 %, respectively”
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We responded to this comment, The sentence has been modified. |
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11 |
Figures 21, 22, 25, 26: Curves in these figures should be redrawn.
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We responded to this comment, Curves have been redrawn |
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Page 21, line 763: What is the difference between the number of impacts required to fracture and the number of blows required to fail?
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First crack impact: It is the number of blows that affect the sample. Failure impact: It is the number of blows that cause the sample to collapse |
Author Response File: 
Author Response.docx
Reviewer 3 Report
This paper has carried out a systematic study on the effect of hybrid synthetic waste fibers (HSWF), temperature and exposure time on the physical and mechanical performances of Ultra-High-Performance Concrete (UHPC), including compressive strength, splitting strength, flexural strength, modulus of elasticity, ultra-sonic pulse velocity, impact energy, and thermal conductivity. The work is sufficient and systematic, and this research is significant for the reuse of HSWF and the development of new UHPC. However, there are problems in the logical framework, language and diagrams in this manuscript. The details are as follows:
1. Highlights: the description is not clear, such as “UHPC with HSFW performs better than UHPC without fibers.”, “When concrete is exposed to heat, adding fibers reduces the degradation”.
2. Abstract: (1) the logic is confused. The author first should explain the curing time and conditions. Then, explain the high temperature exposure plan, and finally, describe the test items after high temperature exposure. (2) 38 line: what is the accelerated curing regime? Is the steam curing at 90℃ for 3 days?
3. Research significance: it is unnecessary to set up this chapter. “1. The significance of this work…” is the Innovation of this paper, and should be introduced in “Introduction” Part. “2. Utilization of hybrid synthetic…” and “5. Research possibilities in the UHPC” are the engineering significance of this study, and may be introduced in “Conclusion” Part.
4. Specimens’ descriptions: the time in high temperature exposure plan is puzzling. Curing time is 28 days, steam curing time is 3 days, testing time is 91 days after curing, the high temperature exposure time is 1 and 2 hours. Please explain these time.
5. Figures should be improved. Fig.1 does not indicate (a), (b), (c). Fig.3 is not clear. The description in Figure 28 is misplaced.
6. English should be further improved.
Author Response
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Reviewer #3: |
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General comments: |
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No. |
Reviewer Comments |
Response |
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1 |
Highlights: the description is not clear, such as “UHPC with HSFW performs better than UHPC without fibers.”, “When concrete is exposed to heat, adding fibers reduces the degradation”.
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We responded to this comment, Required modifications have been made |
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2 |
Abstract: (1) the logic is confused. The author first should explain the curing time and conditions. Then, explain the high temperature exposure plan, and finally, describe the test items after high temperature exposure. (2) 38 line: what is the accelerated curing regime? Is the steam curing at 90℃ for 3 days?
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We responded to this comment, Required modifications have been made |
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3 |
Research significance: it is unnecessary to set up this chapter. “1. The significance of this work…” is the Innovation of this paper, and should be introduced in “Introduction” Part. “2. Utilization of hybrid synthetic…” and “5. Research possibilities in the UHPC” are the engineering significance of this study, and may be introduced in “Conclusion” Part.
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We responded to this comment, Required modifications have been made. |
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4 |
Specimens’ descriptions: the time in high temperature exposure plan is puzzling. Curing time is 28 days, steam curing time is 3 days, testing time is 91 days after curing, the high temperature exposure time is 1 and 2 hours. Please explain these time.
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We responded to this comment, Required modifications have been made. |
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5 |
Figures should be improved. Fig.1 does not indicate (a), (b), (c). Fig.3 is not clear. The description in Figure 28 is misplaced.
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We responded to this comment, Required modifications have been made |
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6 |
English should be further improved.
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We responded to this comment, Required modifications have been made |
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The authors addressed the first round of reviews and it can be accepted.
Author Response
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Reviewer #3: |
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General comments: |
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No. |
Reviewer Comments |
Response |
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1 |
1. Highlights: the description is not clear, such as “UHPC with HSFW performs better than UHPC without fibers.”, “When concrete is exposed to heat, adding fibers reduces the degradation”.
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We responded to this comment, Required modifications have been made. |
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2 |
2. Abstract: (1) the logic is confused. The author first should explain the curing time and conditions. Then, explain the high temperature exposure plan, and finally, describe the test items after high temperature exposure. (2) 38 line: what is the accelerated curing regime? Is the steam curing at 90℃ for 3 days?
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We responded to this comment, The summary has been revised and modified. |
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3 |
3. Research significance: it is unnecessary to set up this chapter. “1. The significance of this work…” is the Innovation of this paper, and should be introduced in “Introduction” Part. “2. Utilization of hybrid synthetic…” and “5. Research possibilities in the UHPC” are the engineering significance of this study, and may be introduced in “Conclusion” Part.
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We responded to this comment, Required modifications have been made |
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4 |
4. Specimens’ descriptions: the time in high temperature exposure plan is puzzling. Curing time is 28 days, steam curing time is 3 days, testing time is 91 days after curing, the high temperature exposure time is 1 and 2 hours. Please explain these time.
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We responded to this comment, Initially, the temperature and exposure time in UHPC was changed from 300 °C to 500 °C for 1 and 2 hours. The ultrasonic pulse, thermal conductivity, compressive strength, flexural strength, splitting, modulus of elasticity, and drop hammer impact (impact resistance, impact energy, and ductility index) behavior of various combinations were investigated after 91 days of steam curing. For steam curing, the temperature was kept at 90°C for three days. |
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5 |
5. Figures should be improved. Fig.1 does not indicate (a), (b), (c). Fig.3 is not clear. The description in Figure 28 is misplaced.
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We responded to this comment, Required modifications have been made
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6 |
6. English should be further improved.
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We responded to this comment, Language and style revision done |
Author Response File: Author Response.docx
Reviewer 2 Report
Some comments are not carried out such as:
Comment 2: Add the research work carried out by Ye Li et al. (2002) to the literature review.
Reference: Ye Li, En-HuaYang, Kang HaiTan, Flexural behavior of ultra-high performance hybrid fiber reinforced concrete at the ambient and elevated temperature. Construction and Building Materials, 2020. 250(11): 118487. DOI:10.1016/j.conbuildmat.2020.118487
Also, the research work of Piotr Smarzewski and Danuta Barnat-Hunek (2017)
Reference: Piotr Smarzewski and Danuta Barnat-Hunek, Effect of Fiber Hybridization on Durability Related Properties of Ultra-High Performance Concrete. International Journal of Concrete Structures and Materials, 2017. 11:315–325. https://doi.org/10.1007/s40069-017-0195-6
These references should be cited in the references list.
Comment 10: Page 19, line 676: Correct the sentence in this line “…were decreased to 7.49%, 5.04 %, and 1.74 %, respectively” (see old version)
Author Response
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Reviewer #2: |
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General comments: |
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No. |
Reviewer Comments |
Response |
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1 |
Reference: Ye Li, En-HuaYang, Kang HaiTan, Flexural behavior of ultra-high performance hybrid fiber reinforced concrete at the ambient and elevated temperature. Construction and Building Materials, 2020. 250(11): 118487. DOI:10.1016/j.conbuildmat.2020.118487 Also, the research work of Piotr Smarzewski and Danuta Barnat-Hunek (2017) Reference: Piotr Smarzewski and Danuta Barnat-Hunek, Effect of Fiber Hybridization on Durability Related Properties of Ultra-High Performance Concrete. International Journal of Concrete Structures and Materials, 2017. 11:315–325. https://doi.org/10.1007/s40069-017-0195-6 These references should be cited in the references list.
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We responded to this comment, Required modifications have been made. |
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2 |
Comment 10: Page 19, line 676: Correct the sentence in this line “…were decreased to 7.49%, 5.04 %, and 1.74 %, respectively” (see old version) |
We responded to this comment, The summary has been revised and modified. |
Author Response File: Author Response.docx
