Mechanical and Thermomechanical Properties of Clay-Cowpea (Vigna Unguiculata Walp.) Husks Polyester Bio-Composite for Building Applications
, Paschal Ateb Ubi 2, Ifeyinwa Ijeoma Obianyo 1, Godwin Mong Kalu-Uka 1,3, Abdulhakeem Bello 1,4, Michael Ikpi Ofem 5, Abel Olajide Olorunnisola 6 and Azikiwe Peter Onwualu 1
Round 1
Reviewer 1 Report
This is exciting research and is highly necessitated to achieve sustainable building materials and housing. Please see my comments on annotated PDF.
Comments for author File: 
Comments.pdf
Author Response
Comments and Suggestions for Authors REVIEWER 1
- Abstract keywords adjusted alphabetically
- Thank you for this observation. Shelter has been replaced with Housing accordingly
- Sustainable building material was mentioned in page 2 lines 50-68
- Underline removed.
- These are the actual samples of the clay used obtained from a previous work in our laboratory.
- The references have all been adjusted and deleted where advised to.
- Improvement on the Introduction and Conclusion has been done.
- Error bars were included to give a view (at a glance) of how the measurements vary from each other however they have been removed
- All fonts have been harmonized on equations and charts.
Author Response File: Author Response.pdf
Reviewer 2 Report
The paper entitled “Mechanical and Thermomechanical Properties of Clay-Cowpea 2 (Vigna Unguiculata walp.) Husks Polyester Bio-Composite for 3 Building Applications” presents the results of the study carried out for investigating the feasibility of creating a clay polymer-based composite using cowpea husk as filler for production of roof tiles. The study has been approached investigating mechanical and thermos-mechanical behaviour of formulated composites throughout different analytical techniques.
The study is very interesting and fascinating and offers an interesting trains of thought on new form of revitalisation of biomass and polymer waste in Africa contributing to cleaning the environment.
The paper is well structured and written, nevertheless I think that the conclusion is not exhaustive and an effort for its improvement is needed to give at this research/study more importance and the possibility to be accessible from a wider public.
Author Response
Comments and Suggestions for Authors REVIEWER 2
The paper entitled “Mechanical and Thermomechanical Properties of Clay-Cowpea 2 (Vigna Unguiculata walp.) Husks Polyester Bio-Composite for 3 Building Applications” presents the results of the study carried out for investigating the feasibility of creating a clay polymer-based composite using cowpea husk as filler for production of roof tiles. The study has been approached investigating mechanical and thermos-mechanical behaviour of formulated composites throughout different analytical techniques.
The study is very interesting and fascinating and offers an interesting trains of thought on new form of revitalisation of biomass and polymer waste in Africa contributing to cleaning the environment.
The paper is well structured and written, nevertheless I think that the conclusion is not exhaustive and an effort for its improvement is needed to give at this research/study more importance and the possibility to be accessible from a wider public.
Answer: Conclusion has been duly modified as requested by reviewer
Author Response File: Author Response.pdf
Reviewer 3 Report
Abstract, please state the point of originality, gap of research it tries to fill, practical and academic contribution. If there may be policy implications, please state that as well. The following part may be useful for including it to abstract after rewriting: the abundance of biomass waste and menace of polymer waste in Africa, it is important 100 to valorise and find alternative economic uses for them, while contributing to cleaning the 101 environment. Thus, this paper presents the experimental investigations towards develop- 102 ing a composite with cowpea husk fibres in unsaturated polyester matrix for sustainable 103 building application. The effect of clay addition on the mechanical and thermo-mechani- 104 cal behaviour of formulated composites was investigated for possible application in roof- 105 ing tiles... Please compare some recent clay research related mechanical properties to identify this research is of high originality and state where SEM was used in other research for clay properties investigation: https://www.nature.com/articles/s41598-020-71605-7 139-159., is there any missing citation? Based on what prior research that you use this method? Table 1, please use repeat header row. 2.3.2 to 2.3.6, no citation 3.2 please expand and describe what are shown in the figures. Lines 368-369, please merge them. Please explain what is Damping factor, Grey relational generation (GRG), Grey relational coefficient (GRC) and Grey relational grade. Similar problem happen in the whole paper. Conclusion, Variations in composition have an impact on the attributes of all the produced 417 composite as they all yielded different results, this one is expected. The addition of cowpea husk fibre to unsaturated polyester resin improved 419 hardness, tensile modulus and flexural modulus but decreased tensile strength 420 and flexural strength, what is the implication of this in, say housing construction as said earlier? According to the Grey relational analysis, the optimal composition for both 422 mono-reinforced and hybrid composite is 18 percent cowpea husk., will this be affected by other factors, such as temperature? State the main contribution of the paper in conclusion and research gap that it fills.
Author Response
Comments and Suggestions for Authors REVIEWER 3
- Abstract, please state the point of originality, gap of research it tries to fill, practical and academic contribution. If there may be policy implications, please state that as well.
Answer: The abstract has been modified as suggested. The originality stems from the fact that CPH has not been explored as potential raw material for roof tiles. Similarly, roof tiles made from biomass, UPT and clay combined good mechanical properties with ecological characteristics that reduces environmental issues. Such combinations provide strategies and alternatives for sustainable resources.
The following part may be useful for including it to abstract after rewriting: the abundance of biomass waste and menace of polymer waste in Africa, it is important 100 to valorise and find alternative economic uses for them, while contributing to cleaning the 101 environment. Thus, this paper presents the experimental investigations towards develop- 102 ing a composite with cowpea husk fibres in unsaturated polyester matrix for sustainable 103 building application. The effect of clay addition on the mechanical and thermo-mechanical behaviour of formulated composites was investigated for possible application in roofing tiles...
- Please compare some recent clay research related mechanical properties to identify this research is of high originality and state where SEM was used in other research for clay properties investigation:
https://www.nature.com/articles/s41598-020-71605-7 139-159., is there any missing citation? Based on what prior research that you use this method?
Answer: We agree that it’s important to compare results but in most cases it usually difficult to have a direct comparison with existing works due to many varying parameters and experimental lab conditions
Missing citation included
This work is based on an existing methodology that is easy and straightforward by https://doi.org/10.1007/s00170-020-05570-w The method was adopted and modified to suit our intended application
- Table 1, please use repeat header row. 2.3.2 to 2.3.6, no citation 3.2 please expand and describe what are shown in the figures.
Answer: Statement has been removed
- Lines 368-369, please merge them.
Answer: Lines have been merged as requested
- Please explain what is Damping factor, Grey relational generation (GRG), Grey relational coefficient (GRC) and Grey relational grade. Similar problem happens in the whole paper.
Answer: Necessary parameters have been duly defined.
- Conclusion, Variations in composition have an impact on the attributes of all the produced composite as they all yielded different results, this one is expected. The addition of cowpea husk fibre to unsaturated polyester resin improved hardness, tensile modulus and flexural modulus but decreased tensile strength and flexural strength, what is the implication of this in, say housing construction as said earlier?
Answer: these properties are due to successful incorporation of UPT, CPH and clay as composites for roof tiles demonstrating the use of biomass, UPT and clay as potential sources of sustainable material. The roof tiles produced combined good mechanical property and have opened up the possibility of using them in building to reduce environmental impact.
- According to the Grey relational analysis, the optimal composition for both 422 mono-reinforced and hybrid composite is 18 percent cowpea husk., will this be affected by other factors, such as temperature?
Answer: Thank you for raising this and we agree that temperature is a very important component and that is why we carried out the visco-elastic measurement from 27oC to 150oC all the composites studied showed loss in stiffness is observed with increase in temperature due to increased particle mobility leading to decrease in storage modulus.
- State the main contribution of the paper in conclusion and research gap that it fills.
Answer: The main contribution and research gap has been included in the Conclusion as advised.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
Many of the previous version problem still exists in this new submission.
Originality of the paper is unclear.
2.3 miss all the citations
The beginning of the paper sounds like the author would like to see if the materials can be used for building but the conclusions and the test results are related to mechanical properties of the clay:
Variations in composition have an impact on the attributes of all the produced composite as they all yielded different results.
• The addition of cowpea husk improved hardness, tensile modulus and flexural modulus but decreased tensile strength and flexural strength.
• From the Grey relational analysis, the optimal composition for both mono-re-inforced and hybrid composite is 18 percent cowpea husk. This implies that the optimum thermo-mechanical properties are obtained at 18% and serves as benchmark for future work.
Why do we need to know these three points? What are the practical values? We have mechanical properties research on clay before. What is the main point of originality?
The abstract should contains academic, practical and policy implications as well as contribution.
The author should state what is SEM, how was SEM applied in previous research like:
Zhang, Y., Pu, S., Li, R.Y.M. et al. Microscopic and mechanical properties of undisturbed and remoulded red clay from Guiyang, China. Sci Rep 10, 18003 (2020). https://doi.org/10.1038/s41598-020-71605-7
The author is advised to compare between their clay research and the previous one as above, as both use SEM for seeing the mechanical properties, so what is the main contribution?
What are "Grey relational generation (GRG), Grey relational coefficient (GRC) and Grey relational grade (GR*grade)"?
4.0 was advised not to use point form, again the authors ignore this comments and point forms remain. May I ask whether the author would like the reviewer to reject it?
It seems most of the comments are ignored and the authors are revising by their own means.
Author Response
Comments and Suggestions for Authors REVIEWER 3 ROUND 2
Originality of the paper is unclear.
Answer: The originality of the paper has been improved and highlighted on line 101 to 110
2.3 miss all the citations
Answer: Citations have been duly included
The beginning of the paper sounds like the author would like to see if the materials can be used for building but the conclusions and the test results are related to mechanical properties of the clay:
Variations in composition have an impact on the attributes of all the produced composite as they all yielded different results.
• The addition of cowpea husk improved hardness, tensile modulus and flexural modulus but decreased tensile strength and flexural strength.
• From the Grey relational analysis, the optimal composition for both mono-re-inforced and hybrid composite is 18 percent cowpea husk. This implies that the optimum thermo-mechanical properties are obtained at 18% and serves as benchmark for future work.
Why do we need to know these three points? What are the practical values?
Answer: This proves the potentials of the composite to be used in building application and also serves as benchmark for future work. Finally, this study has provided data and knowledge to fill the missing gap of using CPH, UPT and clay as a potential and sustainable source of raw material for building application in particular roof tiles.
We have mechanical properties research on clay before. What is the main point of originality?
The abstract should contains academic, practical and policy implications as well as contribution.
Answer: Academic and practical implications has been added. However, we are not aware of any policy documents related to these materials we have studied.
The author should state what is SEM,
Answer: SEM has been stated on line 109
how was SEM applied in previous research like:
Zhang, Y., Pu, S., Li, R.Y.M. et al. Microscopic and mechanical properties of undisturbed and remoulded red clay from Guiyang, China. Sci Rep 10, 18003 (2020). https://doi.org/10.1038/s41598-020-71605-7
The author is advised to compare between their clay research and the previous one as above, as both use SEM for seeing the mechanical properties, so what is the main contribution?
Answer: We would like to thank the reviewer again for raising this. The paper suggested by the reviewer was read and we deduced from the paper that the authors used remoulded and undistributed clay for their work and basically used SEM and XRD for the characterization. The authors made the following conclusions:
- Guiyang red clay has granular-shape, curved-slice and thin layer and flower-shaped ellipsoid aggregates, with point contact, line contact, surface contact and mosaic contact modes. There are X and Y-type cracks and pores in undisturbed red clay, which has flocculation, honeycomb and pseudosphere structures.
- The quantitative analysis of the microstructure of red clay is influenced by the magnification and grey threshold and the recommended magnification ranged from 1,500×to 4,000× and the threshold values are near 130.
- The deviatoric stress–strain curve of the undisturbed red clay from Guiyang exhibited obvious strain-softening behaviour, whereas the remoulded red clay exhibited strain hardening behaviour. For undisturbed red clay, the angle between the shear failure plane and the horizontal plane of the specimen was 60° when the specimen was destroyed, whereas the remoulded red clay exhibited a bulging failure. Also, the strength of undisturbed red clay was higher than that of remoulded red clay.
- In comparison to remoulded red clay, the undisturbed red clay had a denser structure and exhibited obvious structural properties, with the pore distribution in one direction. Also, the pores of the undisturbed red clay were slit-shaped, whereas they were ordered circular-shaped in the remoulded red clay.
However, in our case we worked on a composite of Cowpea husk (CPH), 3% clay and unsaturated polyester (UPT). The percentage of clay in the composite is very small and also does not present a case for direct comparison as proposed by the reviewer. The main focus of the work is the use of CPH biomass and UPT to add value to these materials as sustainable resources.
Nonetheless the 3% clay used in this work was previously characterised in our lab as indicated in the Methods section
What are "Grey relational generation (GRG), Grey relational coefficient (GRC) and Grey relational grade (GR*grade)"?
Answer: Definitions given and highlighted in orange colour in the manuscript.
4.0 was advised not to use point form, again the authors ignore this comments and point forms remain.
Answer: Point form has been removed
Author Response File: Author Response.pdf
Round 3
Reviewer 3 Report
101-111, no citation, I think the author has not revised according to the suggestions made last time and the first time review.
Author Response
Thank you for this observation.
References have been inserted accordingly
