Physical and Mechanical Properties of Sustainable Hydraulic Mortar Based on Marble Slurry with Waste Glass

Round 1

Reviewer 1 Report

in attachement

Comments for author File: Comments.pdf

Author Response

The manuscript entitled “Mechanical and Igrothermal Properties of Sustainable Hydraulic Mortar

Based on Marble Slurry with Waste Glass” is a study that is interesting and the problem is actual, but

I see a lot of issues that need to be corrected. I recommend the paper to be published after major

revision.

I give some specified suggestions below:

• Title: The term “Igrothermal” does not occur in the text of the manuscript. Is it also not widely used term. I suggest change of the title.

Dear reviewer, Thanks for the valuable suggestion. The Title of the paper was changed replacing the term Igrothermal with the term Physical.

• Line 12: what is TP? If it means “Province of Trapani” than it is not understandable to anyone outside Italy.

Dear Reviewer, the abbreviation TP was replaced by Province of Trapani as you suggested. Thanks.

• Line 17: “ (FVS), (CVS), (FSS)” what FVS, CVS, FSS states for? If it is an abbreviation of Italian term than it is not understandable to anyone outside Italy. Those should be corrected to proper English abbreviations in the whole article.

Dear Reviewer, thanks for the comment. The abbreviation FVS was replaced by LGS (stands for Slaked-Lime, Glass, Sand); CVS was replaced by NGS (Natural –Hydraulic-Lime, Glass, Sand) and the term FSS was replaced by LSS that stands for Slaked-Lime, Sieved Sand, As Received Sand.

• Line 18: NHL – what is it? All abbreviations needs to be explained at the first appearance.

Dear Reviewer, thanks. NHL stand for Natural Hydraulic Lime, it was defined in the abstract where it appears for the first time.

• Line 19: “of Threepoint Bending and Compressive Strength tests, Capillary uptake, Helium Pycnometry and Simultaneous Thermal Analysis.” I do not think that capital letters are justified here.

Thanks, the capital letters were removed as you suggested.

• Line 28: “In the last decades, a considerable amount of research has concerned the use of marble [1] and glass powders [2] separately as additives to improve physical and mechanical properties of mortars and concretes.” Are 2 references really “the considerable amount”?

The references from [1] to [7] were inserted concerning the use of marble, while refs from [8] to [18] were added regarding the use of the glass powders. Furthermore, others refs were cited throughout the Introduction section.

• Line 33 “It is well known that cement production is one of the most environmental unfriendly” Should be written “Portland cement”. Other cements have lower environmental impact.

Thanks for the suggestion. The term cement was replaced by the term Portland cement.

• Line 37 “the carbon dioxide to cement weight ratio is close to 1:1” As above.

As above, the term cement was replaced by the term Portland cement.

• Line 98: “the 2 range” the letter “phi” is missing

Thanks for the warning. The greek letter was inserted.

• Line 119: “from marble slurry (F), glass powder (V) and river sand (S) in 1:1:1.5 volume ratio with three different glass grain size, i.e., lower than 125 microns (a), between125 and 210 microns (b), and between 210 and 350 microns (c). Three were composed of natural hydraulic lime (C) with…”(F), (V), (C) – as comment to line 17

The abbreviations were modified throughout the manuscript as described above (line 17).

• Line 129: “The mortars were named as shown in Error! Reference source not found. according to the
• ” Reference?

Thank you for the warning, all the reference issues were fixed.

• Table 1: abbreviations FVS, CVS, FSS are not understandable (mentioned before). What is T.V.?

As above, the abbreviations were modified. The term “T.V.” was replaced by the term “As Received” for better understanding.

• Lines 149-155: “The flexural strength was obtained for each sample by the following equation: … where P is the maximum load, L is the span, b the width of the specimen and h the height measured in the load direction.” This is evident and shouldn’t occur in the article.

Thanks for the suggestion, the obvious description was erased from the manuscript as you indicated.

• Lines 172-175 – as above

Thanks again, the sentence was eliminated.

• Figure 1 (line 212) – very poor quality, too low size of the text.

Dear reviewer thanks for the warning.

• Figure 2 (line 214) – could be larger

Thanks, the dimensions of the Figure were increased

• Figure 3 (line 220) – too low size of the text.

Thanks for the warning, the size of the text was increased

• Line 215, 217, 221: reference missing. Later on also.

The missing references were added

• Figure 1, 2 and 3 again? (lines 236, 242, 263) renumerate please. Please check also references to figures.

Thank you, the problem with the number of the Figures was solved.

• Figure 1 (line 236) – very poor quality, too low size of the text.

The quality of the Figure was improved, the text size was increased.

• Figure 6, 7 (lines 249, 254) – very poor quality, too low size of the text.

Thank you for the warning, the quality of the Figures was improved and the text size increased.

• Figure 2 (line 263) – could be larger

Thank you the size of the Figure was increased

• Figure 4 (line 284) – too low size of the text.

Thanks for the warning, the text size of the Figure was increased

• Line 322: “CO2 and H2Oidr associated weight loss by absorbed water, H2Oabs.” Lower indices needed

Dear Reviewer, the subscripts were corrected as requested.

• Figures 7-9 (329, 331, 333)– too low size of the text.

Thank you for the comment, the text size was increased

• The results of tests for the materials should be in the section of “Materials and Methods” instead the “results” section.

Thanks for the comment, the results of the characterization of the raw materials were moved in the “Materials and Methods” section as you suggested.

• The results section should be supported by discussion with previous research.

Dear Reviewer, thanks for the suggestion. The results proposed were compared with those reported by previous research, the added paragraphs were highlithed in green in the manuscript.

• The volume of the Introduction section is to low as well as the number of references. It should be extended.

Dear Reviewer, thanks for the suggestion. The volume of the Introduction was increased as well as the number of references. The added paragraphs were highlithed in green in the manuscript.

Reviewer 2 Report

Ref: recycling-1196414

Title: Mechanical and Igrothermal Properties of Sustainable Hydraulic Mortar Based on Marble Slurry with Waste Glass

Comments to Author:

The paper study the possibility of using marble slurry, as raw material to produce lime, and waste glass powder as pozzolanic aggregate to produce mortars based on waste materials. Mineralogical and microscopic analyses as well as mechanical and hygric properties of the different mortars were determinated and compared.

The research idea (i.e. use marble slurry as raw material and waste glass powder as pozzolanic aggregate to produce mortars) is not completely novel or original, but the methodology used is rational and gives clear insight of the issue.

The paper is in general well written; however, since the reviewer is not native English speaker, this not implies that correctness of the English language is adequate.

The contents of this paper are adequate, and the results are credible However, some questions listed as follows should be tackled or explained by the authors:

• In the title why the authors use the term “igrothermal”? In my opinion this term, in the context of the article, it is not correct.
• -Throughout the text is possible to find "reference source not found", please correct them.
• Most of the figures are difficult to read, please improve the image quality or increase the font size.
• Please correct the figure numbers. The numerations are not sequential.
• Introduction: The introduction is clear and presents the research problem succinctly. I only suggest the reading of two good articles about the research subject j.jclepro.2015.02.049 and j.cemconcomp.2014.02.007.
• Materials and Methods:
  • Line 84-85: In the sentence “The amount of slurry produced in this site is around 2·105 tons/year [5].” It is interesting information however, is a generic statement. I propose that the authors add what is done to this production: go to waste deposit? or is it used by other industries?
  • Line 86-88: In the sentence “Slaked lime was obtained by mixing quicklime and distilled water in a ratio of 1:2.5 by weight, and after ten days, the mortars were manufactured”. Can the authors comment the decision to use only 10 days of maturation. In general, the results improve with the maturation time of the pastes.
  • Line 95-96: “moreover grain size distribution of glass powder was evaluated using standard sieves on a kilogram of glass powder.” Can the authors add some information about the grain size distribution of the used sand?
  • Line 93-94: “Low Vacuum Scanning electron microscopy (SEM) with Energy Dispersion X-Ray Spectroscopy (EDS)”, line 101-102 “The ESEM used in this work is an FEI Quanta 200 FEG coupled with EDAX elemental analysis” and line 256 “The use of a Scanning Electron Microscope (SEM-ESEM) combined with the use of EDX Microscopy”. Please standardize the used nomenclature.
  • Line 118-130: the paragraph should be rewritten. It is difficult to understand the composition of the mortars, namely of the FSS mortar; moreover, in the mortars with slaked lime, water wasn’t used in the mix?
  • Line 143: “climatic chamber at a temperature of 22 ± 2°C and relative humidity 90 ± 5% RH until the end of the curing (3 months)”. Please explain better why the authors select this proceeding. Did the air lime mortars hardened with the selected relative humidity? What was the cure conditions at the first five days?
  • The mechanical and water absorption tests were made at the 90 days of curing? Please add this information.
  • Line 185-189: “The mass of each sample was recorded after 0, 10, 90 min of immersion (…)” the absorption measures were only made at these times? if it is possible, add the absorption curves until the saturation.
• Results:
  • Line 225-226: In the sentence “mortars with coarser glass grain size were prepared using a grain size distribution from 210 to 350 µm instead of 350 to 500 µm as in pozzolanic test”. Can the authors explained this option, since this range has not yet been presented.
  • In Figure 9, should be added some arrows indicating the reaction fringes, as well as the EDS with the compositions of the reactions fringes.
  • Section 3.2.2.: the authors referee that “(FVS) were (…) closer to those exhibited by NHL 3.5 based samples (CVS)” I do not understand this affirmation! In my opinion, the CVS are clearly higher than FVS. Can the author comment the results?
  • Line 295: “better thermal insulation performance” why do the authors introduce this concept?
  • Section 3.2.2. to 3.2.5: Although the authors of the carried out paper compare the behavior between the mortars, the obtained results are not correlated, therefore the discussion of the results should be rewritten and should be supported by results of other authors.

After the comparison between the mortars, where differences and similarities should be revealed, should be pointed out the reason for that behavior and discussed what is the effect of the use of marble slurry in the mortars behavior, as well as the use of glass powder. The influence of the cure conditions on the mechanical performance should also be discussed, by taking into account the results of the carried out tests.

Why FVS mortars present a very high porosity, a higher mechanical strength and lower water absorption coefficient, than FSS. Can the authors clarify this aspect?

Author Response

Title: Mechanical and Igrothermal Properties of Sustainable Hydraulic Mortar Based on Marble Slurry with Waste Glass

Comments to Author:

The paper study the possibility of using marble slurry, as raw material to produce lime, and waste glass powder as pozzolanic aggregate to produce mortars based on waste materials. Mineralogical and microscopic analyses as well as mechanical and hygric properties of the different mortars were determinated and compared.

The research idea (i.e. use marble slurry as raw material and waste glass powder as pozzolanic aggregate to produce mortars) is not completely novel or original, but the methodology used is rational and gives clear insight of the issue.

The paper is in general well written; however, since the reviewer is not native English speaker, this not implies that correctness of the English language is adequate.

The contents of this paper are adequate, and the results are credible However, some questions listed as follows should be tackled or explained by the authors:

• In the title why the authors use the term “igrothermal”? In my opinion this term, in the context of the article, it is not correct.

Dear Reviewer, thanks for the comment. The title was modified as follows: “Mechanical and Physical Properties of Sustainable Hydraulic Mortar Based on Marble Slurry with Waste Glass”

• -Throughout the text is possible to find "reference source not found", please correct them.

Thanks again. The references to the Figures were corrected.

• Most of the figures are difficult to read, please improve the image quality or increase the font size.

Thanks for the comment, all the Figures were modified to improve the quality as suggested.

• Please correct the figure numbers. The numerations are not sequential.

Thanks for the comment. The numerations were corrected.

• Introduction: The introduction is clear and presents the research problem succinctly. I only suggest the reading of two good articles about the research subject j.jclepro.2015.02.049 and j.cemconcomp.2014.02.007.

Thank you for the suggestion. The suggested articles were read and cited in the manuscript.

• Materials and Methods:
  • Line 84-85: In the sentence “The amount of slurry produced in this site is around 2·105 tons/year [5].” It is interesting information however, is a generic statement. I propose that the authors add what is done to this production: go to waste deposit? or is it used by other industries?

As you proposed, the sentence “that mostly is disposed filling the quarry” was added to better explain that most of the marble slurry produced is unused.

• Line 86-88: In the sentence “Slaked lime was obtained by mixing quicklime and distilled water in a ratio of 1:2.5 by weight, and after ten days, the mortars were manufactured”. Can the authors comment the decision to use only 10 days of maturation. In general, the results improve with the maturation time of the pastes.

Thanks for the comment. The following sentence was introduced to explain the reason why the mortars were manufactured after 10 days. “After ten days an almost complete conversion of Calcium Oxide to Calcium Hydroxide occurs and, hence, the mortars were manufactured”.

In the paragraph 3.1.3. Kilned Marble Slurry and Slaked Lime, the sentence “STA performed on slaked lime (Figure 7) indicates that after 10 days an almost complete conversion of Calcium oxide to calcium hydroxide occurs” was also inserted.

• Line 95-96: “moreover grain size distribution of glass powder was evaluated using standard sieves on a kilogram of glass powder.” Can the authors add some information about the grain size distribution of the used sand?

Thanks for the suggestion. The information about the used river sand was added in the following sentence: “ According to the supplier the granulometric range of the used sand is from 0.125 to 5.6mm according to the granulometric distribution available in the supplementary materials.”

• Line 93-94: “Low Vacuum Scanning electron microscopy (SEM) with Energy Dispersion X-Ray Spectroscopy (EDS)”, line 101-102 “The ESEM used in this work is an FEI Quanta 200 FEG coupled with EDAX elemental analysis” and line 256 “The use of a Scanning Electron Microscope (SEM-ESEM) combined with the use of EDX Microscopy”. Please standardize the used nomenclature.

Thanks for the advice. The terms EDAX and EDX were changed in EDS.

• Line 118-130: the paragraph should be rewritten. It is difficult to understand the composition of the mortars, namely of the FSS mortar; moreover, in the mortars with slaked lime, water wasn’t used in the mix?

No water was added to the mixtures (renamed as LGS) as it’s contained in the slaked lime obtained from marble slurry.

• Line 143: “climatic chamber at a temperature of 22 ± 2°C and relative humidity 90 ± 5% RH until the end of the curing (3 months)”. Please explain better why the authors select this proceeding. Did the air lime mortars hardened with the selected relative humidity? What was the cure conditions at the first five days?

Dear Reviewer, Thanks for the comment. The relative paragraph was modified as follows in order to response to the above questions. “The specimens were cured in the molds for 5 days in laboratory conditions (22 ± 2 °C and 50 ± 5% RH) in order to allow the samples to reach adequate mechanical properties to facilitate the demolding process without causing damages. After 5 days, the samples were removed from the molds and placed in a climatic chamber at 22 ± 2°C and 90 ± 5% RH for 3 months. The high relative humidity was chosen to favor the hydraulic hardening with respect to air hardening for the proposed hydraulic binder based mortars (LGS), while the quite long curing time (3 months) was chosen to allow the air-lime (LSS) to reach an adequate hardening.”

• The mechanical and water absorption tests were made at the 90 days of curing? Please add this information.

Thanks again. Yes, the information was added for mechanical and water absorption tests.

• Line 185-189: “The mass of each sample was recorded after 0, 10, 90 min of immersion (…)” the absorption measures were only made at these times? if it is possible, add the absorption curves until the saturation.

The measurement was performed according to national standard test, thanks to reviewer we added the information to saturation.

• Results:
  • Line 225-226: In the sentence “mortars with coarser glass grain size were prepared using a grain size distribution from 210 to 350 µm instead of 350 to 500 µm as in pozzolanic test”. Can the authors explained this option, since this range has not yet been presented.

As the coarser fraction showed a low pozzolanic behaviour we chose to reduce it in order to increase the expected hydraulicity of the mortars.

• In Figure 9, should be added some arrows indicating the reaction fringes, as well as the EDS with the compositions of the reactions fringes.

Thanks for the comment the arrows indicating the reaction fringes were added in the Figure 9.

• Section 3.2.2.: the authors referee that “(FVS) were (…) closer to those exhibited by NHL 3.5 based samples (CVS)” I do not understand this affirmation! In my opinion, the CVS are clearly higher than FVS. Can the author comment the results?
• Dear reviewer. Thanks for the comment. The relative paragraph was modified as follows: “The values of flexural strength of the proposed material (LGS) were clearly higher than those obtained by simple air-hardening lime mortars (LSS), and particularly for the lowest grain size particles, the LGS mortars reached more than half of the NGS mortars”.
• Line 295: “better thermal insulation performance” why do the authors introduce this concept?

Thanks, we introduce this hypothesis as the main advantage of producing a mortar from waste materials is increasing the sustainability and a lower thermal conductivity can offer a higher thermal insulation.

• Section 3.2.2. to 3.2.5: Although the authors of the carried out paper compare the behavior between the mortars, the obtained results are not correlated, therefore the discussion of the results should be rewritten and should be supported by results of other authors.

Dear Reviewer, thanks for the suggestion. The results proposed were compared with those reported by previous research, the added paragraphs were highlithed in green in the manuscript.

• After the comparison between the mortars, where differences and similarities should be revealed, should be pointed out the reason for that behavior and discussed what is the effect of the use of marble slurry in the mortars behavior, as well as the use of glass powder. The influence of the cure conditions on the mechanical performance should also be discussed, by taking into account the results of the carried out tests.

Dear Reviewer, differences and similarities of the mortars behaviour were better explained in the results and discussion section.

The experimental characterization carried out in this work was aimed to investigate the physical and mechanical properties of a sustainable mortars entirely based on waste materials: marble slurry and waste glass. The obtained results showed an evident pozzolanic behavior especially at lower grainsize and that this system, which exploits the coupling of two waste materials, their transformation and combined use, can be used to obtain mortars with higher mechanical performances compared to traditional air lime mortars without affecting their physical properties.

Since the principal aim of the authors was to assess the feasibility of a binding system entirely obtained by waste materials and its comparison with traditional ones, the influence of curing conditions on the physical and mechanical performance of similar sustainable binding systems will be evaluated in future works. However, the following sentence was added in the 3.3 Compressive test section to take into account  the influence of the curing conditions on the mechanical performance of the mortars:

“It is also important to note that several studies have reported that, although early age strength can be lower compared to the reference when recycled waste glass is used in concrete, later age strength may increase [48,49]. For this reason, it is plausible to expect that the compressive strength of the LGS mortars at later curing time may further increase not only for the progress of the carbonation process but also for the continuation of the pozzolanic reactions between the glass powders and the residual portlandite”.

Why FVS mortars present a very high porosity, a higher mechanical strength and lower water absorption coefficient, than FSS. Can the authors clarify this aspect?

Thanks for the question. Despite the higher porosity of the renamed LGS mortars, thanks to their hydraulic behaviour (evidenced by the results reported in Figures 14, 15, 16), the mechanical strength were higher than the renamed LSS air hardening mortars. The following sentence was added to the manuscript to clarify the results obtained by the water absorption tests:

“The lower water absorption coefficient of the LGS mortars can be due to the higher average dimensions of the pores compared to the air lime mortars that lead to a slower water absorption rate due capillary. This hypothesis can be validated by observing the water absorption curves reported in Figure 12. It is evident that after 24h the mortars LGS125 and LGS210 do not reach the saturation unlike all the other mortars”.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I accept the corrections. Thanks to authors for enhancing of the article.