Lime and Cement Plasters from 20th Century Buildings: Raw Materials and Relations between Mineralogical–Petrographic Characteristics and Chemical–Physical Compatibility with the Limestone Substrate

Round 1

Reviewer 1 Report

The article has an interesting and pertinent theme and is well structured and written. But it needs to improve the state of the art. The article presents many references, but not about the most important.

The following is suggested:

Abstract - it should contain more information on the main or main conclusions of the work. 

1.1. State of art and aims of research

A state of knowledge is not presented, only historical references about mortars. It is only mentioned that bibliography is quite scarce. It is necessary to make known what studies exist. 

3. Materials and methods

It should be included in the methodology what magnification is used in the images of SEM-EDS analyses. 

In these sentences below it is necessary to put some references, since it is a statement and it is necessary to give examples. Which also shows the lack of state-of-the-art references.

in 5. Discussion of results

"(...)is not a surprising result since several papers [ref], especially those dealing with mortar repair in historic buildings, came to the same conclusion in similar contexts."

in 6. Conclusions

"Indeed, several papers [ref] describe the compatibility between limestone
and lime mortars(...) but very few papers [ref] deal with mortars as old
as tens of years."

 

Author Response

Dear Reviewer 1,

the manuscript has been extensively revised and many parts of the text have been rewritten and improved according to reviewer suggestions.

Below you can find all the responses to your comments point by point. In addition, the Word file of the manuscript with all the changes made highlighted was attached.

Please see the attachment.

_____________

Response to reviewer 1

The article has an interesting and pertinent theme and is well structured and written. But it needs to improve the state of the art. The article presents many references, but not about the most important.

The following is suggested:

Abstract - it should contain more information on the main or main conclusions of the work. 

Answer:

We thank the reviewer for the suggestion; so, the abstract text has been modified.

1.1. State of art and aims of research

A state of knowledge is not presented, only historical references about mortars. It is only mentioned that bibliography is quite scarce. It is necessary to make known what studies exist.

Answer:

According to the suggestion of reviewer, the paragraph 1.1 has been modified according to the suggestion of reviewer, modifying some sentences and integrating new bibliographic references.

3. Materials and methods

It should be included in the methodology what magnification is used in the images of SEM-EDS analyses.

Answer:

Thank to reviewer for the suggestion; the single magnification data used of the SEM-EDS images are added in the caption text of figures 10 and 11.

In these sentences below it is necessary to put some references, since it is a statement and it is necessary to give examples. Which also shows the lack of state-of-the-art references.

in 5. Discussion of results

"(...) is not a surprising result since several papers [ref], especially those dealing with mortar repair in historic buildings, came to the same conclusion in similar contexts."

Answer:

According to the suggestion of reviewer some bibliographic references are added in the sentence.

in 6. Conclusions

"Indeed, several papers [ref] describe the compatibility between limestone
and lime mortars(...) but very few papers [ref] deal with mortars as old
as tens of years."

Answer:

We thank the reviewer for the suggestion; the meaning of the above sentence had already been expressed and better described in the manuscript. Therefore, in order to avoid repetition, and given the length of the conclusion section, this sentence has been cut out.

Author Response File: Author Response.docx

Reviewer 2 Report

This paper presents the characterization of a few plasters from 20th century, applied in the renovation of the limestone walls of a historical building. These plasters, from different compositions and binder types are characterised in terms of their compositions and physical behaviour. The purpose of the paper is to discuss the chemical-physical compatibility between the diverse layers and the limestone substrate. The topic is interesting due to the relevance of applying successful interventions, with modern materials, on decayed old plasters. It is not so timely, since there are plenty of works reporting the incompatibility between hydraulic modern mortars and old masonry walls, as recognized by the authors. However, the detailed description of the materials and their accurate technical-scientific characterization makes this paper worth to be published, since it enriches the documented repertoire of this subject. The paper explores a significant number of old samples of mortars and stones from the support. The state-of–art and historical background is accurate, although sometimes too detailed, considering the purpose of the paper. The English writing is also correct and pleasant, although not perfect. More detailed comments are given below:

• Some suggestions of English writing improvement are given in the attached pdf.
• In the title and in the abstract, authors refer that they are dealing with hydraulic and cement mortars, but diverse samples of non-hydraulic mortars are characterized and a very relevant reference to these mortars is made in the conclusions. Authors should correct this inconsistency.
• Abstract: bedding mortar is used to apply masonry units or tiles, so it is not like “arriccio” as suggested by authors, which is the “the brown coat”. Please clarify.
• Authors should clarify the notions of “mortars” and “plasters” throughout the entire paper. Plaster is the coating, while mortar is the material used in that function (or other like bedding, pointing). There are many examples where authors use both terms at the same type as if they are identifying two different elements, which is inaccurate.
• Section 1.2: please introduce here some more information about the location of this city in the Sardinia island, in Italy.
• A new structure is proposed for section 4, with two parts: 1) “characterization of mortars components” (or mortars and stone support), that includes 4.1-4.7; and 2) “mortars physical properties”.
• Section 4.1, text “1) Cement Mortars…are thick plasters used to fill wall voids and/or to consolidate fractures and discontinuities”. Please replace “thick plasters” by “coarse mortars”. Also, authors mentioned earlier that are dealing with “brown coat (hereafter called “arriccio” …) and finishing coat (hereafter “intonachino”).” So, why there is here a mention to filling voids?
• Section 4.1, text “2) Hydraulic Lime Mortars…”: replace “finishing plasters” by “finishing mortars”.
• Section 4.1, text “3) Finishing mortars…”. Authors should use same criterion as in 1) and 2), referring to the binder type. HLM are also “finishing plasters”! Possibilities are: “air or feebly hydraulic lime fine mortars". Table 1 should be corrected in accordance.
• Table 1: besides plaster layers, authors also include paints and limestone from support. Please correct the title in accordance. Also, the introduction to the data from paints and limestone included in Table 1 is not clear in the text.
• Section 4.4, text “the higher noise of the background signal that suggests lower crystallinity for the presence of C-S-H, C-A-H phases in the binder”. Authors should include a discussion supporting why these mortars were considered to be made of cement, since there are other binders that also provide C-S-H and C-A-H, especially in old plasters (e.g. pozzolanic soils).
• Page 19, text “C-S-H fibrous aggregates of hydrated Ca-rich calcium…”. Improve support to this statement, since C-S-H can be obtained also from C3S and the mentioned C2S is also present in hydraulic lime.
• Section 4.6, text “…but for the same reasons as mentioned above, the calculation did not include fine and coarse mesoscopic porosity”. Porosity results presented in table 2 are several orders of magnitude below the typical values found in these mortars (25-30%). Please add a comment, mentioning the relevance of including this porosity values.
• Table 2, remove column “TOT”. This information can be conveyed in the text.
• Section 5.5. Physical-mechanical properties: sections incorrectly numbered from now on. Also, mechanical properties were not studied.
• Page 25, “…the low amount of aggregates contributes to a more packed and less porous structure, at least for what concerns large pores.” Mix-design of mortars points out that the porosity increases as aggregates volume decreases, since the volume of paste rises and this is the phase with the higher contribution to porosity. See “https://doi.org/10.1016/j.cemconcomp.2018.03.005”. Please add a discussion on this, mentioning the relation with the obtained results.
• Section “Discussion of the results”, a new structure is proposed for this section. The mention to the mortars decay is here stated for the first time. If the authors want to relate the decay with the measured properties, the decay should be introduced previously, in section 4. For instance in table 1, near the corresponding mortar. In this way it is clear which are the samples with decay (no decay is mentioned for HLM and it is not clear if it is because this mortars does not show any decay or if it is not relevant for the discussion).
• Page 27, text “Hereafter the main features of the three types of plasters are summarized, before discussing the data”. In this presentation, authors should specify which features result directly from measured properties (binder content) and those that come from indirect assumptions (higher hydraulicity). Hidraulicity was not measured.
• Page 27, text “SEM imaging and microanalyses, coupled to petrophysical properties…” and following. The discussion is essentially supported on these techniques. The discussion on the physical properties of the mortars, and corresponding relation with decay, is missing.
• Page 28, text “What is worth of note here is the role of aggregates and especially their abundance. It seems that “intonachino” layers, characterized by the lowest content of aggregates, act in a counter-productive way. These finishing plasters are often detached by the substrate, either wall-rock or “arriccio” mortars.” The lower aggregate proportion, as well as their grain size, in intonachino” layers plays a role in the multilayer system. So, stating that they “act in a counter-productive way” is irrelevant. Additionally, authors should refer to bibliography to explain the detachment of the outer layer (see previous reference).
• Reference to “Portland” cement in conclusions is avoidable. Paper does not present results to support this statement.
• Page 29: description of paints should be given in 4) and not in 3). It is stated in page 12 that paints will not be studied, which is incorrect. Contents are unbalanced in conclusions and in discussion: paints are deeply explored in conclusions, more than the other layers and are lacking in discussion.

Comments for author File: Comments.pdf

Author Response

Dear Reviewer 2,

the manuscript has been extensively revised and many parts of the text have been rewritten and improved according to reviewer suggestions.

Below you can find all the responses to your comments point by point. In addition, the Word file of the manuscript with all the changes made highlighted was attached.

Please see the attachment.

_____________

Response to reviewer 2

This paper presents the characterization of a few plasters from 20th century, applied in the renovation of the limestone walls of a historical building. These plasters, from different compositions and binder types are characterised in terms of their compositions and physical behaviour. The purpose of the paper is to discuss the chemical-physical compatibility between the diverse layers and the limestone substrate. The topic is interesting due to the relevance of applying successful interventions, with modern materials, on decayed old plasters. It is not so timely, since there are plenty of works reporting the incompatibility between hydraulic modern mortars and old masonry walls, as recognised by the authors. However, the detailed description of the materials and their accurate technical-scientific characterisation makes this paper worth to be published, since it enriches the documented repertoire of this subject. The paper explores a significant number of old samples of mortars and stones from the support. The state-of–art and historical background is accurate, although sometimes too detailed, considering the purpose of the paper. The English writing is also correct and pleasant, although not perfect. More detailed comments are given below:

• Some suggestions of English writing improvement are given in the attached pdf.

Answer:

We thank the reviewer for the suggestions. The highlighted words are been corrected.

• In the title and in the abstract, authors refer that they are dealing with hydraulic and cement mortars, but diverse samples of non-hydraulic mortars are characterised and a very relevant reference to these mortars is made in the conclusions. Authors should correct this inconsistency.

Answer:

We thank the reviewer for suggestion. In the abstract a better description of kinds of studied materials has been added.

• Abstract: bedding mortar is used to apply masonry units or tiles, so it is not like “arriccio” as suggested by authors, which is the “the brown coat”. Please clarify.

Answer:

According to the reviewer suggestion, in the abstract the erroneously used word 'bedding' (which created a misunderstanding in the meaning of the sentence) has been deleted.

• Authors should clarify the notions of “mortars” and “plasters” throughout the entire paper. Plaster is the coating, while mortar is the material used in that function (or other like bedding, pointing). There are many examples where authors use both terms at the same type as if they are identifying two different elements, which is inaccurate.

Answer:

The use and meaning of "mortar" and "plaster" words in the manuscript has been homogenized according to the reviewer suggestion.

• Section 1.2: please introduce here some more information about the location of this city in the Sardinia island, in Italy.

Answer:

More information about the Cagliari city and its location in the Mediterranean have been added in the text of 1.2 section.

• A new structure is proposed for section 4, with two parts: 1) “characterization of mortars components” (or mortars and stone support), that includes 4.1-4.7; and 2) “mortars physical properties”.

Answer:

According to the reviewer suggestion, a new structure has been added for section 4, divided in two parts: "4.1 Compositional characterization of mortars", (that includes 4.1.1->4.1.6 subparagraphs, and "4.2 Physical properties" (that include the two subparagraphs: 4.2.1 Mortar samples, and 4.2.2 Limestone samples.

Section 4.1, text “1) Cement Mortars…are thick plasters used to fill wall voids and/or to consolidate fractures and discontinuities”. Please replace “thick plasters” by “coarse mortars”. Also, authors mentioned earlier that are dealing with “brown coat (hereafter called “arriccio” …) and finishing coat (hereafter “intonachino”).” So, why there is here a mention to filling voids?

Answer:

According to the reviewer suggestion, the sentence has been modify as: "1) Cement Mortars (signed as CM) are plasters present unevenly in the cave inner wall, sometimes also used for the installation of hydraulic or lighting systems or to fill wall voids and/or to consolidate fractures and discontinuities (Figs. 5b, c, g)."

• Section 4.1, text “2) Hydraulic Lime Mortars…”: replace “finishing plasters” by “finishing mortars”.
• Section 4.1, text “3) Finishing mortars…”. Authors should use same criterion as in 1) and 2), referring to the binder type. HLM are also “finishing plasters”! Possibilities are: “air or feebly hydraulic lime fine mortars". Table 1 should be corrected in accordance.

Answer:

Welcoming the reviewer's suggestions, the two sentences mentioned above and the Table 1 have been modify in accordance to the meaning of definitions used in the manuscript.

• Table 1: besides plaster layers, authors also include paints and limestone from support. Please correct the title in accordance. Also, the introduction to the data from paints and limestone included in Table 1 is not clear in the text.

Answer:

According to the reviewer suggestion, the word "limestone substrate" has been added in the title of paper because, although not the main focus of the research, the physical properties of limestone were studied and presented in the paper to better understand the behaviour of mortars with respect to the rock substrate. The paint coats were not object of this study, but a rough observation and thus they are reported in Table 1 because belong in any case to the sampling of materials from the cave room. For this reason it did not seem appropriate to include it in the title.

• Section 4.4, text “the higher noise of the background signal that suggests lower crystallinity for the presence of C-S-H, C-A-H phases in the binder”. Authors should include a discussion supporting why these mortars were considered to be made of cement, since there are other binders that also provide C-S-H and C-A-H, especially in old plasters (e.g. pozzolanic soils).

Answer:

The different composition of cement-based mortars (CM) from those based on hydraulic-lime (HLM) has been discussed in the petrography and SEM sections. Both CM and HLM have C-S-H and C-A-H phases, but the hydraulic-lime mortars have more lime amounts, while the cement mortars are rare. The CM mortas also have C₄AF phases. In addition to the compositional features, the macroscopic characteristics are also different: the binders of the hydraulic-lime mortar and lime-based finishing plasters commonly exhibit lighter colours, whitish (PL-INT) to greyish-white (HLM-AR), whereas the cement mortars exhibit a typical Portland colour, from grey (CM-AR2) to brownish-grey (CM-AR1). In addition, HLM-AR mortars locally retain lumps of unmixed slaked lime, whereas cement mortars there are not.

• Page 19, text “C-S-H fibrous aggregates of hydrated Ca-rich calcium…”.Improve support to this statement, since C-S-H can be obtained also from C3S and the mentioned C2S is also present in hydraulic lime.

Answer:

According to the reviewer suggestion, the sentence has been improved and strengthened in its meaning, also mentioning the presence between the C-S-H phases of alite besides the belite.

• Section 4.6, text “…but for the same reasons as mentioned above, the calculation did not include fine and coarse mesoscopic porosity”.Porosity results presented in table 2 are several orders of magnitude below the typical values found in these mortars (25-30%). Please add a comment, mentioning the relevance of including this porosity values.

Answer:

The porosity determined by image analysis refers to macro-pores with radius on average > 50 mm. As well known and as reported in section 4.2, the open porosity (to helium) of these mortars is higher (about 25-40%). Thus, according to the reviewer suggestion, this aspect has been commented in the caption of Table 2 and in the text of manuscript.

• Table 2, remove column “TOT”. This information can be conveyed in the text.

Answer:

The column "TOT" has removed from the Table 2.

• Section 5.5. Physical-mechanical properties: sections incorrectly numbered from now on. Also, mechanical properties were not studied.

Answer:

The section 5.5. has modified as "4.2 Physical properties"

• Page 25, “…the low amount of aggregates contributes to a more packed and less porous structure, at least for what concerns large pores.”Mix-design of mortars points out that the porosity increases as aggregates volume decreases, since the volume of paste rises and this is the phase with the higher contribution to porosity. See “https://doi.org/10.1016/j.cemconcomp.2018.03.005”. Please add a discussion on this, mentioning the relation with the obtained results.

Answer:

The sentence was written incorrectly and unclearly. Thus, on the basis of the reviewer's suggestion it was therefore rewritten correctly and other sentences were added to better explain the issue with new bibliographic references.

• Section “Discussion of the results”, a new structure is proposed for this section. The mention to the mortars decay is here stated for the first time. If the authors want to relate the decay with the measured properties, the decay should be introduced previously, in section 4. For instance in table 1, near the corresponding mortar. In this way it is clear which are the samples with decay (no decay is mentioned for HLM and it is not clear if it is because this mortars does not show any decay or if it is not relevant for the discussion).

Answer:

According to the reviewer suggestion, the structure of paper has been modified. New text on the decay issue, besides the section "Discussion of the results", has been added in the new paragraph: "4.1.2 Stratigraphy of plasters and decay".

• Page 27, text “Hereafter the main features of the three types of plasters are summarized, before discussing the data”. In this presentation, authors should specify which features result directly from measured properties (binder content) and those that come from indirect assumptions (higher hydraulicity). Hidraulicity was not measured.
• Page 27, text “SEM imaging and microanalyses, coupled to petrophysical properties…”and following. The discussion is essentially supported on these techniques. The discussion on the physical properties of the mortars, and corresponding relation with decay, is missing.

Answer:

According to the reviewer suggestions, new text about the peculiar compositional and physical characteristics of different mortar groups has been added in the "Discussion of the results" section.

• Page 28, text “What is worth of note here is the role of aggregates and especially their abundance. It seems that “intonachino” layers, characterized by the lowest content of aggregates, act in a counter-productive way. These finishing plasters are often detached by the substrate, either wall-rock or “arriccio” mortars.”The lower aggregate proportion, as well as their grain size, in intonachino” layers plays a role in the multilayer system. So, stating that they “act in a counter-productive way” is irrelevant. Additionally, authors should refer to bibliography to explain the detachment of the outer layer (see previous reference).

Answer:

The text of sentence at pag. 28 has been modified according to the reviewer suggestion and adding the bibliographic reference.

• Reference to “Portland” cement in conclusions is avoidable. Paper does not present results to support this statement.

Answer:

According to the reviewer suggestion, the “Portland” references have been deleted from the text of conclusions section.

• Page 29: description of paints should be given in 4) and not in 3). It is stated in page 12 that paints will not be studied, which is incorrect. Contents are unbalanced in conclusions and in discussion: paints are deeply explored in conclusions, more than the other layers and are lacking in discussion.

Answer:

According to the reviewer suggestion, new text has been added in the final part of discussion section and the texts of points 3 and 4 of conclusions section have been modified.

Author Response File: Author Response.docx

Reviewer 3 Report

The paper presents a detailed and systematic study on hydraulic-lime and cement plasters from 20th century. Many experimental data, from several samples, are presented and discussed in detail.

The results are well discussed, and the conclusions are sound and consistent.  I suggest to accept the paper as it is.

 

Author Response

Dear Reviewer 3,

the manuscript has been extensively revised and many parts of the text have been rewritten and improved according to reviewer suggestions.

Below you can find all the responses to the comments point by point of three reviewers. In addition, the Word file of the manuscript with all the changes made highlighted was attached.

Please see the attachment.

_______

Response to Reviewer's comments:

Reviewer 1

The article has an interesting and pertinent theme and is well structured and written. But it needs to improve the state of the art. The article presents many references, but not about the most important.

The following is suggested:

Abstract - it should contain more information on the main or main conclusions of the work. 

Answer:

We thank the reviewer for the suggestion; so, the abstract text has been modified.

 

1.1. State of art and aims of research

A state of knowledge is not presented, only historical references about mortars. It is only mentioned that bibliography is quite scarce. It is necessary to make known what studies exist.

Answer:

According to the suggestion of reviewer, the paragraph 1.1 has been modified according to the suggestion of reviewer, modifying some sentences and integrating new bibliographic references.

 

3. Materials and methods

It should be included in the methodology what magnification is used in the images of SEM-EDS analyses.

Answer:

Thank to reviewer for the suggestion; the single magnification data used of the SEM-EDS images are added in the caption text of figures 10 and 11.

 

In these sentences below it is necessary to put some references, since it is a statement and it is necessary to give examples. Which also shows the lack of state-of-the-art references.

in 5. Discussion of results

"(...) is not a surprising result since several papers [ref], especially those dealing with mortar repair in historic buildings, came to the same conclusion in similar contexts."

Answer:

According to the suggestion of reviewer some bibliographic references are added in the sentence.

 

in 6. Conclusions

"Indeed, several papers [ref] describe the compatibility between limestone
and lime mortars(...) but very few papers [ref] deal with mortars as old
as tens of years."

Answer:

We thank the reviewer for the suggestion; the meaning of the above sentence had already been expressed and better described in the manuscript. Therefore, in order to avoid repetition, and given the length of the conclusion section, this sentence has been cut out.

 

______

 

Reviewer 2

 

This paper presents the characterization of a few plasters from 20th century, applied in the renovation of the limestone walls of a historical building. These plasters, from different compositions and binder types are characterised in terms of their compositions and physical behaviour. The purpose of the paper is to discuss the chemical-physical compatibility between the diverse layers and the limestone substrate. The topic is interesting due to the relevance of applying successful interventions, with modern materials, on decayed old plasters. It is not so timely, since there are plenty of works reporting the incompatibility between hydraulic modern mortars and old masonry walls, as recognized by the authors. However, the detailed description of the materials and their accurate technical-scientific characterization makes this paper worth to be published, since it enriches the documented repertoire of this subject. The paper explores a significant number of old samples of mortars and stones from the support. The state-of–art and historical background is accurate, although sometimes too detailed, considering the purpose of the paper. The English writing is also correct and pleasant, although not perfect. More detailed comments are given below:

• Some suggestions of English writing improvement are given in the attached pdf.

Answer:

We thank the reviewer for the suggestions. The highlighted words are been corrected.

• In the title and in the abstract, authors refer that they are dealing with hydraulic and cement mortars, but diverse samples of non-hydraulic mortars are characterized and a very relevant reference to these mortars is made in the conclusions. Authors should correct this inconsistency.

Answer:

We thank the reviewer for suggestion. In the abstract a better description of kinds of studied materials has been added.

 

• Abstract: bedding mortar is used to apply masonry units or tiles, so it is not like “arriccio” as suggested by authors, which is the “the brown coat”. Please clarify.

Answer:

According to the reviewer suggestion, in the abstract the erroneously used word 'bedding' (which created a misunderstanding in the meaning of the sentence) has been deleted.

 

• Authors should clarify the notions of “mortars” and “plasters” throughout the entire paper. Plaster is the coating, while mortar is the material used in that function (or other like bedding, pointing). There are many examples where authors use both terms at the same type as if they are identifying two different elements, which is inaccurate.

Answer:

The use and meaning of "mortar" and "plaster" words in the manuscript has been homogenized according to the reviewer suggestion.

 

• Section 1.2: please introduce here some more information about the location of this city in the Sardinia island, in Italy.

Answer:

More information about the Cagliari city and its location in the Mediterranean have been added in the text of 1.2 section.

 

• A new structure is proposed for section 4, with two parts: 1) “characterization of mortars components” (or mortars and stone support), that includes 4.1-4.7; and 2) “mortars physical properties”.

Answer:

According to the reviewer suggestion, a new structure has been added for section 4, divided in two parts: "4.1 Compositional characterization of mortars", (that includes 4.1.1->4.1.6 subparagraphs, and "4.2 Physical properties" (that include the two subparagraphs: 4.2.1 Mortar samples, and 4.2.2 Limestone samples.

 

Section 4.1, text “1) Cement Mortars…are thick plasters used to fill wall voids and/or to consolidate fractures and discontinuities”. Please replace “thick plasters” by “coarse mortars”. Also, authors mentioned earlier that are dealing with “brown coat (hereafter called “arriccio” …) and finishing coat (hereafter “intonachino”).” So, why there is here a mention to filling voids?

Answer:

According to the reviewer suggestion, the sentence has been modify as: "1) Cement Mortars (signed as CM) are plasters present unevenly in the cave inner wall, sometimes also used for the installation of hydraulic or lighting systems or to fill wall voids and/or to consolidate fractures and discontinuities (Figs. 5b, c, g)."

 

• Section 4.1, text “2) Hydraulic Lime Mortars…”: replace “finishing plasters” by “finishing mortars”.
• Section 4.1, text “3) Finishing mortars…”. Authors should use same criterion as in 1) and 2), referring to the binder type. HLM are also “finishing plasters”! Possibilities are: “air or feebly hydraulic lime fine mortars". Table 1 should be corrected in accordance.

Answer:

Welcoming the reviewer's suggestions, the two sentences mentioned above and the Table 1 have been modify in accordance to the meaning of definitions used in the manuscript.

 

• Table 1: besides plaster layers, authors also include paints and limestone from support. Please correct the title in accordance. Also, the introduction to the data from paints and limestone included in Table 1 is not clear in the text.

Answer:

According to the reviewer suggestion, the word "limestone substrate" has been added in the title of paper because, although not the main focus of the research, the physical properties of limestone were studied and presented in the paper to better understand the behaviour of mortars with respect to the rock substrate. The paint coats were not object of this study, but a rough observation and thus they are reported in Table 1 because belong in any case to the sampling of materials from the cave room. For this reason it did not seem appropriate to include it in the title.

 

• Section 4.4, text “the higher noise of the background signal that suggests lower crystallinity for the presence of C-S-H, C-A-H phases in the binder”. Authors should include a discussion supporting why these mortars were considered to be made of cement, since there are other binders that also provide C-S-H and C-A-H, especially in old plasters (e.g. pozzolanic soils).

Answer:

The different composition of cement-based mortars (CM) from those based on hydraulic-lime (HLM) has been discussed in the petrography and SEM sections. Both CM and HLM have C-S-H and C-A-H phases, but the hydraulic-lime mortars have more lime amounts, while the cement mortars are rare. The CM mortas also have C₄AF phases. In addition to the compositional features, the macroscopic characteristics are also different: the binders of the hydraulic-lime mortar and lime-based finishing plasters commonly exhibit lighter colours, whitish (PL-INT) to greyish-white (HLM-AR), whereas the cement mortars exhibit a typical Portland colour, from grey (CM-AR2) to brownish-grey (CM-AR1). In addition, HLM-AR mortars locally retain lumps of unmixed slaked lime, whereas cement mortars there are not.

 

• Page 19, text “C-S-H fibrous aggregates of hydrated Ca-rich calcium…”.Improve support to this statement, since C-S-H can be obtained also from C3S and the mentioned C2S is also present in hydraulic lime.

Answer:

According to the reviewer suggestion, the sentence has been improved and strengthened in its meaning, also mentioning the presence between the C-S-H phases of alite besides the belite.

 

• Section 4.6, text “…but for the same reasons as mentioned above, the calculation did not include fine and coarse mesoscopic porosity”.Porosity results presented in table 2 are several orders of magnitude below the typical values found in these mortars (25-30%). Please add a comment, mentioning the relevance of including this porosity values.

Answer:

The porosity determined by image analysis refers to macro-pores with radius on average > 50 mm. As well known and as reported in section 4.2, the open porosity (to helium) of these mortars is higher (about 25-40%). Thus, according to the reviewer suggestion, this aspect has been commented in the caption of Table 2 and in the text of manuscript.

 

• Table 2, remove column “TOT”. This information can be conveyed in the text.

Answer:

The column "TOT" has removed from the Table 2.

 

• Section 5.5. Physical-mechanical properties: sections incorrectly numbered from now on. Also, mechanical properties were not studied.

Answer:

The section 5.5. has modified as "4.2 Physical properties"

 

• Page 25, “…the low amount of aggregates contributes to a more packed and less porous structure, at least for what concerns large pores.”Mix-design of mortars points out that the porosity increases as aggregates volume decreases, since the volume of paste rises and this is the phase with the higher contribution to porosity. See “https://doi.org/10.1016/j.cemconcomp.2018.03.005”. Please add a discussion on this, mentioning the relation with the obtained results.

Answer:

The sentence was written incorrectly and unclearly. Thus, on the basis of the reviewer's suggestion it was therefore rewritten correctly and other sentences were added to better explain the issue with new bibliographic references.

 

• Section “Discussion of the results”, a new structure is proposed for this section. The mention to the mortars decay is here stated for the first time. If the authors want to relate the decay with the measured properties, the decay should be introduced previously, in section 4. For instance in table 1, near the corresponding mortar. In this way it is clear which are the samples with decay (no decay is mentioned for HLM and it is not clear if it is because this mortars does not show any decay or if it is not relevant for the discussion).

Answer:

According to the reviewer suggestion, the structure of paper has been modified. New text on the decay issue, besides the section "Discussion of the results", has been added in the new paragraph: "4.1.2 Stratigraphy of plasters and decay".

 

• Page 27, text “Hereafter the main features of the three types of plasters are summarized, before discussing the data”. In this presentation, authors should specify which features result directly from measured properties (binder content) and those that come from indirect assumptions (higher hydraulicity). Hidraulicity was not measured.
• Page 27, text “SEM imaging and microanalyses, coupled to petrophysical properties…”and following. The discussion is essentially supported on these techniques. The discussion on the physical properties of the mortars, and corresponding relation with decay, is missing.

Answer:

According to the reviewer suggestions, new text about the peculiar compositional and physical characteristics of different mortar groups has been added in the "Discussion of the results" section.

 

• Page 28, text “What is worth of note here is the role of aggregates and especially their abundance. It seems that “intonachino” layers, characterized by the lowest content of aggregates, act in a counter-productive way. These finishing plasters are often detached by the substrate, either wall-rock or “arriccio” mortars.”The lower aggregate proportion, as well as their grain size, in intonachino” layers plays a role in the multilayer system. So, stating that they “act in a counter-productive way” is irrelevant. Additionally, authors should refer to bibliography to explain the detachment of the outer layer (see previous reference).

Answer:

The text of sentence at pag. 28 has been modified according to the reviewer suggestion and adding the bibliographic reference.

 

• Reference to “Portland” cement in conclusions is avoidable. Paper does not present results to support this statement.

Answer:

According to the reviewer suggestion, the “Portland” references have been deleted from the text of conclusions section.

 

• Page 29: description of paints should be given in 4) and not in 3). It is stated in page 12 that paints will not be studied, which is incorrect. Contents are unbalanced in conclusions and in discussion: paints are deeply explored in conclusions, more than the other layers and are lacking in discussion.

Answer:

According to the reviewer suggestion, new text has been added in the final part of discussion section and the texts of points 3 and 4 of conclusions section have been modified.

 

______

 

Reviewer 3

• The paper presents a detailed and systematic study on hydraulic-lime and cement plasters from 20th century. Many experimental data, from several samples, are presented and discussed in detail.
• The results are well discussed, and the conclusions are sound and consistent.  I suggest to accept the paper as it is.

Answer:

Thank you vey much!

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have addressed my previous comments, so the paper can be accepted.

Author Response

Dear Reviewer,
attached you find the new version (2) of revised manuscript with tracked changes according to the suggestions of academic Editor.

 

Best regards

Author Response File: Author Response.pdf