Mechanical Performance of Concrete Made with the Addition of Recycled Macro Plastic Fibres

Round 1

Reviewer 1 Report

This paper studies the mechanical properties of concrete made with recycled coarse plastic fibers. In general, this research is very innovative and has no research significance. In addition, there are too few experimental data, and there are not many experimental analysis methods. No consideration is given to the workability of concrete after adding plastic fibers, such as the fluidity of the concrete. Therefore, I am very sorry that I have to reject this article.

Author Response

Firstly, we would like to emphasize that the authors appreciate the instructive reviews and comments that have undoubtedly improved our article. The responses of authors to each comment have been marked in red colour below.

Reviewer 1

 This paper studies the mechanical properties of concrete made with recycled coarse plastic fibers. In general, this research is very innovative and has no research significance. In addition, there are too few experimental data, and there are not many experimental analysis methods. No consideration is given to the workability of concrete after adding plastic fibers, such as the fluidity of the concrete. Therefore, I am very sorry that I have to reject this article.

In response to the reviewer, to the best of the author´s knowledge there is no previous studies about the use of recycled plastic waste from food packaging, which are difficult to recycled given to its multilayer composition, in concrete as macrofibre. The experimental data presented corresponded to the mechanical performance. It has been already published the environmental assessment of this produced material through leaching to determine the elements released at higher levels and identifying if the plastic waste released any element at levels higher than those legally regulated.

Pollutant potential of reinforced concrete made with recycled plastic fibers from food packaging waste Pietro A. Vaccaro, Adela P. Galvín, Jesús Ayuso, Angelica Lozano-Lunar, Antonio López-Uceda. Appl. Sci. 2021, 11, 8102. https://doi.org/10.3390/app11178102

Regarding to the workability, it is mentioned in the manuscript that it was aimed the S3 slump class (10-15 cm). It is a fact that the incorporation of macrofibre decreases the workability, but in any case, slump values were in the S3 range.

In addition, the authors would like to point out that the conclusions have been changed to improve the section. It has been synthetised and bullet points have substituted the extended paragraph.

Reviewer 2 Report

As main idea, which is sustained by literature and present study, the fibers support the tensile strength by bending, the small fibers are responsible for small cracks and the large ones for large post-cracking cracks. Compressive strength may or may not increase depending on the PET fiber reinforcement dosage.

Few more references could be included:

Corbu O.; Bompa D.V.; Szilagyi H.;  Eco-efficient cementitious composites with large amounts of waste glass and plastic. Proceedings of the Institution of Civil Engineers – Engineering Sustainability, 2021, Paper 2000045 https://doi.org/10.1680/jensu.20.00045

Platon M.A.;, Nemes O.;, Tiuc A.E.; Vasile O.; Paduretu S.Phono-Absorbent Behavior of New Fiberglass Plates from Mixed Plastic Material Wastes.  Materials Design and Applications III, 2021, 

The results are sound and sustained by the research. 

Author Response

Firstly, we would like to emphasize that the authors appreciate the instructive reviews and comments that have undoubtedly improved our article. The responses of authors to each comment have been marked in red colour below.

Reviewer 2

As main idea, which is sustained by literature and present study, the fibers support the tensile strength by bending, the small fibers are responsible for small cracks and the large ones for large post-cracking cracks. Compressive strength may or may not increase depending on the PET fiber reinforcement dosage.

Few more references could be included:

Corbu O.; Bompa D.V.; Szilagyi H.;  Eco-efficient cementitious composites with large amounts of waste glass and plastic. Proceedings of the Institution of Civil Engineers – Engineering Sustainability, 2021, Paper 2000045 https://doi.org/10.1680/jensu.20.00045

Platon M.A.;, Nemes O.;, Tiuc A.E.; Vasile O.; Paduretu S.Phono-Absorbent Behavior of New Fiberglass Plates from Mixed Plastic Material Wastes.  Materials Design and Applications III, 2021, 

The results are sound and sustained by the research. 

Thank you for your useful comment. Introduction section has been revised and content on the use of recycled plastic in construction material has been extended. It has been added the references mentioned along with other papers.

1. Mohan, H. T.; Jayanarayanan, K.; Mini, K. M. Recent trends in utilization of plastics waste composites as construction materials. Build. Mater. 2020, 121520. https://doi.org/10.1016/j.conbuildmat.2020.121520
2. Platon, M. A.; Nemes, O.; Tiuc, A. E.; Vasile, O.; Paduretu, S. Phono-Absorbent Behavior of New Fiberglass Plates from Mixed Plastic Material Wastes. In Materials Design and Applications III, Springer 2021 67-76. DOI: 1007/978-3-030-68277-4_5
3. Mohammadinia, A.; Wong, Y.C.; Arulrajah, A.; Horpibulsuk, S. Strength evaluation of utilizing recycled plastic waste and recycled crushed glass in concrete footpaths. Build. Mater. 2019, 197, 489–496, https://doi.org/10.1016/j.conbuildmat.2018.11.192
4. Corbu, O.; Bompa, D. V; Szilagyi, H. Eco-efficient cementitious composites with large amounts of waste glass and plastic. Inst. Civ. Eng. - Eng. Sustain. 2021, 1–11, https://doi.org/10.1680/jensu.20.00048
5. Thorneycroft, J.; Orr, J.; Savoikar, P.; Ball, R.J. Performance of structural concrete with recycled plastic waste as a partial replacement for sand. Build. Mater. 2018, 161, 63–69, https://doi.org/10.1680/jensu.20.00048

 

In addition, the authors would like to point out that the conclusions have been changed to improve the section. It has been synthetised and bullet points have substituted the extended paragraph.

 

 

Author Response File: Author Response.docx

Reviewer 3 Report

Reviewer #Comments:

 

 

The paper is concerned to an interesting research work related to the analysis of the mechanical and physical behaviour of the hardened concrete reinforced with macro plastic fibres (RPFs) obtained from food packaging waste (FPW) discarded during the packaging phase. The main development of this work is considered to be the use of waste material derived from the processing of plastic for food packaging, instead of commercial plastic fibres. The paper is well organized and with acceptable number of references, illustrations and tables. It is also noticed that the authors have followed the manuscript submission instructions.

 

 

The following points should be considered:

 

Introduction – More recent works could be referred in the Introduction.

 

Pag. 3 – Figure 2: Please be consistent with other Figures and use (a), (b), and (c) for each picture.

 

Pag. 7 – line 239: Regarding Figure 6, no justification was made for the exception of specimen PFRC-2, which achieved a value of 31% higher than the reference PFRC-REF. Some explanation or analysis should be made for this difference of values.

Comments for author File: Comments.pdf

Author Response

Firstly, we would like to emphasize that the authors appreciate the instructive reviews and comments that have undoubtedly improved our article. The responses of authors to each comment have been marked in red colour below.

Reviewer 3

The paper is concerned to an interesting research work related to the analysis of the mechanical and physical behaviour of the hardened concrete reinforced with macro plastic fibres (RPFs) obtained from food packaging waste (FPW) discarded during the packaging phase. The main development of this work is considered to be the use of waste material derived from the processing of plastic for food packaging, instead of commercial plastic fibres. The paper is well organized and with acceptable number of references, illustrations and tables. It is also noticed that the authors have followed the manuscript submission instructions.

The following points should be considered:

-Introduction – More recent works could be referred in the Introduction.

-Pag. 3 – Figure 2: Please be consistent with other Figures and use (a), (b), and (c) for each picture.

-Pag. 7 – line 239: Regarding Figure 6, no justification was made for the exception of specimen PFRC-2, which achieved a value of 31% higher than the reference PFRC-REF. Some explanation or analysis should be made for this difference of values.

Thank you for your comment. With regards to the points indicated:

-Introduction section has been revised and content on the use of recycled plastic in construction material has been extended. It has been added the following references:

1. Mohan, H. T.; Jayanarayanan, K.; Mini, K. M. Recent trends in utilization of plastics waste composites as construction materials. Build. Mater. 2020, 121520. https://doi.org/10.1016/j.conbuildmat.2020.121520
2. Platon, M. A.; Nemes, O.; Tiuc, A. E.; Vasile, O.; Paduretu, S. Phono-Absorbent Behavior of New Fiberglass Plates from Mixed Plastic Material Wastes. In Materials Design and Applications III, Springer 2021 67-76. DOI: 1007/978-3-030-68277-4_5
3. Mohammadinia, A.; Wong, Y.C.; Arulrajah, A.; Horpibulsuk, S. Strength evaluation of utilizing recycled plastic waste and recycled crushed glass in concrete footpaths. Build. Mater. 2019, 197, 489–496, https://doi.org/10.1016/j.conbuildmat.2018.11.192
4. Corbu, O.; Bompa, D. V; Szilagyi, H. Eco-efficient cementitious composites with large amounts of waste glass and plastic. Inst. Civ. Eng. - Eng. Sustain. 2021, 1–11, https://doi.org/10.1680/jensu.20.00048
5. Thorneycroft, J.; Orr, J.; Savoikar, P.; Ball, R.J. Performance of structural concrete with recycled plastic waste as a partial replacement for sand. Build. Mater. 2018, 161, 63–69, https://doi.org/10.1680/jensu.20.00048

 

- Thank you for your comment, we have reviewed and corrected the caption.

- Thank you for your comment, this result has been attributed by the “the greater modulus of elasticity presented by the FRP than the CPF´s one.”

In addition, the authors would like to point out that the conclusions have been changed to improve the section. It has been synthetised and bullet points have substituted the extended paragraph.

 

Author Response File: Author Response.docx

Reviewer 4 Report

The article deals with an interesting and innovative topic, however I believe that in the upload a version still in draft has been put under review. The revisions will be based on this document and not on the precedents:

1) the introduction is complete, particular starting point for some explanations regarding the poor interaction between plastic and concrete can be taken from the article: https://doi.org/10.1016/j.cscm.2020.e00467

2) Often the standards are indicated with the wording UNE instead of UNI, it would be appropriate to correct them along the text.

3) Did you find pull-out of fibers in the flexural test? If yes, it would be necessary to document them also with some photos.

4) A curiosity: with the C_MOD bending test would it be possible to calculate the fracture energy and therefore the level of adhesion of the two types of fibers with the cement?

5) In the conclusions to the first point a sentence is repeated three times should be corrected.

Author Response

Firstly, we would like to emphasize that the authors appreciate the instructive reviews and comments that have undoubtedly improved our article. The responses of authors to each comment have been indicated in the attached file.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

• I keep the same comment for the previous round of review.

  There are many studies on adding recycled plastic fiber to concrete. For example, the following references.

  https://doi.org/10.1016/j.compstruct.2012.09.019

  https://doi.org/10.1016/j.wasman.2016.03.005

  https://doi.org/10.1016/j.wasman.2007.09. 011

  https://doi.org/10.1016/B978-0-08-102676-2.00021-9

  In addition, most of the numbers in this article are meaningless. For example, Figure 2, Figure 3, Figure 4. Among them, Figure 2 and Figure 3 do not have any novelty. Figure 4 is also a very common four-point bending tensile test. So in general, the content of this article is very incomplete.

   

  The workability of concrete is very important, especially after adding fibers. The author did not pay attention to operability but summarized it in one or two sentences.

Author Response

The authors haven’t found any studies in which multilayer plastic waste from packaging are incorporated as fibres in concrete. Due to its multilayer composition its usual current destiny is landfilling, so, this study aims to valorise this stream waste. This contributes to the scientific-technical knowledge on incorporating such a waste in the new paradigm of circular economy. A new phrase has been included in the manuscript to highlight the scientific novelty that this work aims.

All the references indicated by the reviewer were previously included except to the first one, which has been included now (in line 92). The authors would like to point out that the references indicated by the reviewer, among the literary review carried out by the authors, deals with other types of plastic waste such as PET from plastic bottles (1ºref)) and the rest of the references are reviews about the use of recycled plastic in concrete. To the best of the authors´ knowledge, none of the references mentions the use of multilayer plastic waste in these terms. This research attempts to fulfil this novelty gap trying to valorise this waste stream.

Following the suggestions made by reviewer 1 in round 2, Figure 2, Figure 3 and Figure 4 have been removed.

Workability issue has been extended in the manuscript as follows:

“The slump ranged between 15 cm for C-REF and 10 cm for PFRC-6 mix. Slump values were lower as macro-fibre content increased, in agreement with Gu and Ozbakkaloglu [19].”

The authors have considered that the term operability is related to the workability, in any case, if it were not, the authors would like to know what the reviewer means specifically.

The authors appreciate the instructive reviews and comments that have undoubtedly improved our article. Thank you for the suggestions.

Author Response File: Author Response.docx

Reviewer 4 Report

The author responded to all question, the article can be accepted in the present form.

Author Response

Thank you very much for your acceptance.

Round 3

Reviewer 1 Report

The authors have explained the innovation of this article. But the innovation is still insufficient. The multilayer plastic mentioned by the author appears only once in the whole article. I don't think that adding a new phrase can reflect the innovation of an article. It does not specify the difference between multilayer plastic and other plastics. Such as the difference between compressive strength and flexural strength and so on. Is adding every different plastic to concrete every new innovation?

At present, in order to protect the environment, most of the concrete is recycled and reused. But the concrete added with plastic will not be conducive to recycling and sorting in the future.
      

Author Response

Not applicable