Non-Conventional Reinforced EPS and Its Numerical Examination
Round 1
Reviewer 1 Report
The main advantage of the suggested improvements to EPS is a small increase in physical strenght. This may be valid for higly compressed uses as for exemple baseplate exterior insulation where you will find as for all polystyrene products an inverse relationship between strenght and density. To place 2nd hand plastic straws inside the foam seems to be a well minded but absurd production process. The real problem of the (incompletely) described exterior insulation are cavities, joints and thermal bridges. They are in most cases completely reinforced by a sythetic fiber mesh in the stucco/plaster. The drawing is incomplete in this sense. The suggested improvents are thus treated with scientific methods but in my opinion completely irrelevant.
Author Response
Thank you for your review and your remarks.
Our goal with this research work was to examine the possibilities of strengthening the EPS with the usage of waste or by-product. The external insulation was just mentioned as a possible usage of the XPS. The goal of the research was to approach the mechanical properties of XPS.
Due to the experimental tests and the FEM analysis, we described the material model and the necessary strength value and we have determined the bilinear hardening model and the two characteristic moduli of the new materials.
Reviewer 2 Report
see attached file
Comments for author File: 
Comments.docx
Author Response
Thank you for your review and your remarks.
- Amount of additives: a table was added.
- Same amount of straw was used in all specimens and the straw was distributed randomly.
Thanks for your remarks on the hydrophilic behaviour of straw; our future plan is to use torrefied biomass for further investigation, since our expectation to increase the hydrophobic behaviour of the sample, however the strength properties will most likely be decreasing.
Reviewer 3 Report
This work is devoted to Examination of reinforced EPS with non-conventional additives.
In the opinion of the Reviewer, the layout of the work does not meet the standards required for this type of scientific article.
First, there is no clear-cut goal of the work in relation to research and the associated numerical modeling. The tests were described in a very general manner, without specifying the basic parameters of the materials produced, such as, for example, density, etc. This could be a very interesting part of the work, comparing the parameters of new materials with the parameters of the reference polystyrene without additives (EPS) and the exemplary XPS.
In the part concerning numerical methods, the assumptions, computational models, initial and boundary conditions as well as model discretization are not described. The lack of such information disqualifies the presentation of the modeling results, as it is not known for what assumptions were obtained. Additionally, legends in the graphical results are illegible. This point should be significantly expanded.
In the case of thermal analyzes, FEM modeling lacks information on how convection inside the tubes was taken into account in the modeling?
The lack of detail in the numerical calculations and the detailed recognition of physical phenomena (in order to select computational models) raises serious doubts about the obtained results described in Lines 428-430.
Additional remarks below:
- In Figure 1, the reinforced layer is missing
- In Figure 4 there is an incorrect signature
- The diagram in Figure 14 without description of the units shows little and is illegible (poor workmanship)
- The sentence on lines 66-67 is not true. Rather, it applies to XPS styrofoam.
- Table 1 - Why were these research results just quoted and inserted into the paper? Generally known parameters.
- XPS is used in soil mainly due to its low water absorption. Compressive strength has an additional effect only in the floors or under the foundation slab - Line 128-130
- On which markets is such a price difference? In some countries, the price of XPS is several times higher than EPS.
- In the introduction, there are too few references to new world research on modified polystyrenes.
- Summary does not contain clear conclusions from research, modeling and their reference for further work. Needs correction.
The subject deserves to be continued, but this work in the presented form requires additions and thorough modifications.
Author Response
Thank you for your review and your remarks.
Our goal with this research work was to examine the possibilities of strengthening the EPS with the usage of waste or by-product. Due to the experimental tests and the FEM analysis, we described the material model and the necessary strength value, and we have determined the bilinear hardening model and the two characteristic moduli of the new materials.
A table was included with the used amount of additives and the densities of the samples. The initial and boundary conditions as well as model discretization is also included in the manuscript.
The tubes filled with PS so there is no convection inside the tubes.
In both cases, it was necessary to create a geometric model. When creating the model, a geometry was used according to the new, square-shaped forming chamber. During the tests, the whole volume temperature of 20°C was assumed as initial condition and the boundary conditions were:
- initial temperature of upper surface: 100°C
- initial temperature of lower surface: 20°C
- thermal conductivity of PS: 038 W/mK
- stiffening material (LDPE) thermal conductivity: 33 W/mK
- side walls assumed as adiabatic walls
Figure 1 and Figure 4 were deleted.
Figure 14, 15 and 16 were explained detailed in the text, but the order of these figures were modified.
Lines 66-67 were corrected.
Table 1 is a collection of the data. We inserted with the purpose of assisting further researchers.
The price of EPS is significantly lower e.g. on the Hungarian market than the XPS.
The summary was corrected.
The research will be certainly continued, thank you for your support.
Round 2
Reviewer 1 Report
Research is conducted properly, but the topic is still irrelevant.
Author Response
Dear Reviewer,
Thank you for your work and comments.
Reviewer 3 Report
Correct figure 17 - the lines go through the description
Author Response
Dear Reviewer,
Thank you for your work and your comments.
The text under Figure 17 has been modified.
