Experimental Assessment of Post-Fire Residual Material Properties of Marlstone
, Ema Jankovičová 1, Kateřina Kovářová 2, Eva Matoušková 3, Pavla Ryparová 1 and Tomáš Čejka 1Round 1
Reviewer 1 Report
Comments and Suggestions for Authors1.Why selected the experimental temperatures of 620 °C, 870 °C, and 1100 °C ?
2.Section 3.1 appears twice in the manuscript (Line 252 and Line 268)
3.The figure number is 19 (Line 560).
4.The experimental study lacks structural characterization methods, such as SEM–EDS analysis.
5.The cooling rate of water-quenching method is significantly higher than realistic fire conditions.
6.The relationship between the color changes and mineralogical phase transformations is not sufficiently discussed.
Author Response
We sincerely thank the reviewer for the insightful comments and constructive suggestions, which have greatly contributed to improving the clarity, quality, and overall readability of the manuscript. We have carefully considered all the remarks and have revised the text accordingly to address the points raised
Comment 1: Why selected the experimental temperatures of 620 °C, 870 °C, and 1100 °C ?
Response 1: The selected experimental temperatures were chosen based on previous experimental observations, which indicated that changes in marlstone at lower temperatures were limited, and on practical constraints related to the number of available specimens, which did not allow systematic testing across the full temperature range. This study therefore intentionally targets higher temperatures that can be reached during fire events in order to assess the material response and survival under more severe thermal conditions.
A brief explanation has also been added to text.
Comment 2: Section 3.1 appears twice in the manuscript (Line 252 and Line 268)
Response 2: The duplicate numbering of Section 3.1 has been corrected.
Comment 3: The figure number is 19 (Line 560).
Response 3: The figure numbering has been corrected; Figure 19 now has the correct label.
Comment 4: The experimental study lacks structural characterization methods, such as SEM–EDS analysis.
Response: We agree that advanced structural characterization methods such as SEM–EDS can provide valuable additional insight. As stated in the Conclusions section, the application of techniques including SEM, XRD, and FTIR is planned as part of future work, building on the results and limitations of the present study.
Comment 5: The cooling rate of water-quenching method is significantly higher than realistic fire conditions.
Response 5: The water-quenching procedure was applied following approaches reported in previous studies on thermally exposed stone materials, including those cited in this manuscript [10–12]. Also, During fire extinguishing, the temperature drop on the stone surface can be extremely rapid, potentially inducing significant thermal stress. The chosen water-quenching method aims to simulate this most aggressive scenario, representing the maximum thermal shock the material could experience, rather than typical cooling rates under slower fire decay. This approach allows assessment of the stone’s behavior under worst-case conditions, which is critical for understanding potential damage mechanisms.
Comment 6: The relationship between the color changes and mineralogical phase transformations is not sufficiently discussed.
Response 6: We have added a discussion on the potential correlation between colour changes and mineralogical transformations, and have also highlighted the possible influence of the natural heterogeneity of marlstone samples on the observed results.
Reviewer 2 Report
Comments and Suggestions for AuthorsOverall, the topic and focus of the paper are interesting and relevant, particularly regarding the behaviour of heritage stone materials exposed to fire. The experimental approach is comprehensive and potentially valuable for conservation and post-fire assessment. However, the manuscript has several weaknesses in structure, clarity, and methodological description. For these reasons, a major revision is recommended. Detailed comments are provided below.
- State of the art review. The paragraph is very detailed, precise, and clear; however, for improved readability, it should be summarised, either by introducing a table or by significantly reducing the text to focus only on the most relevant aspects of each cited study. One possible solution would be to create a summary table and include in the text only a brief synthesis highlighting the main trends emerging from the selected papers.
The review should also indicate whether standards or regulations addressing this topic exist (i.e. UNI EN).
Page 4, line 178. Which of the cooling methods discussed in the literature have you selected for your study? Please add some explanation for the choice of methods and analyses in relation to the investigated case studies.
Page 5, line 200 – “petrographically…”. Add references.
Page 5, lines 212–213. Add references.
Page 5, line 223. “Marlstone is characterized by low capillary rise”. Do you mean capillary absorption? Please clarify or justify this statement.
Page 6, line 233. Why should rapid heating and cooling occur during a fire? This concept requires clearer explanation.
Page 6, lines 235–238. Please add references for this sentence.
Page 6, line 244. Including a figure showing the macroscopic appearance of the rock would be useful.
Tables 1 and 2. These tables could be moved to the Supplementary Materials. In the text, clearly indicate which sample codes belong to Group 1 and Group 2.
It is likely that the last part of the previous paragraph should be moved to Section 3.1, where the samples used for the analyses are described. The geological formation should also be specified.
Page 8, line 280. The description of sample group M3 is missing.
Methods section. The description of the methods is lengthy and discursive. It is important to be more concise and focus on the purpose of each method. Detailed explanations of the working principles are unnecessary; instead, add bibliographic references (for example, in the section on CIELab).
For colour measurements, was a colorimeter used? Please clarify.
The sentence “In general, reflectance spectroscopy refers to a broad range of techniques that examine and record how electromagnetic radiation interacts with matter” is unclear.
In the methods, it is not specified how Young’s modulus was measured.
The petrographic description of samples subjected to thermal cycles is unclear. Are the changes described in the discussion (lines 505–520, p. 19) those observed in thin sections?
Page 21, lines 550–574. Please summarise these results. The reason for using this technique is unclear. It is difficult to identify structural changes in rocks with this method. Are there bibliographic references supporting the use of this technique for this type of analysis?
Section 4.4 – Elemental concentrations analysis. These results were obtained by XRF, correct? To improve clarity, specify this in the section title.
In Table 11, samples from Group M2 are not included.
At 1100 °C, it is stated that calcite is no longer present according to petrographic observation, which is also confirmed by the hydrochloric acid test, whereas XRF shows an increase in Ca concentration. How can this be explained?
How were the samples prepared for XRF analysis? Please add this information to the Methods section.
Colour difference (ΔE*). For Group 1, it is unusual that ΔE* is lower at 1100 °C. Why does this trend occur? Could it be related to colour heterogeneity on the sample surface?
Conclusions. The petrographic results are not discussed in conclusions. For future analyses, it is also recommended to include the determination of the material’s physical properties.
Author Response
We sincerely thank the reviewer for the insightful comments and constructive suggestions, which have greatly contributed to improving the clarity, quality, and overall readability of the manuscript. We have carefully considered all the remarks and have revised the text accordingly to address the points raised
Overall, the topic and focus of the paper are interesting and relevant, particularly regarding the behaviour of heritage stone materials exposed to fire. The experimental approach is comprehensive and potentially valuable for conservation and post-fire assessment. However, the manuscript has several weaknesses in structure, clarity, and methodological description. For these reasons, a major revision is recommended. Detailed comments are provided below.
Comment 1: State of the art review. The paragraph is very detailed, precise, and clear; however, for improved readability, it should be summarised, either by introducing a table or by significantly reducing the text to focus only on the most relevant aspects of each cited study. One possible solution would be to create a summary table and include in the text only a brief synthesis highlighting the main trends emerging from the selected papers.
Response 1: We appreciate the reviewer’s suggestion regarding the state-of-the-art review. We believe that an extensive literature review is essential, as it provides the necessary background for the research presented in this article. Indeed, other reviewers even suggested extending the review to ensure completeness. In an effort to balance these opposing recommendations, we have added a summary table that highlights the key aspects of the cited studies, providing the reader with a faster orientation while maintaining the detailed discussion. This approach enhances readability and allows the main trends to be easily identified without omitting important contextual information.
Comment 2: The review should also indicate whether standards or regulations addressing this topic exist (i.e. UNI EN).
Response 2: There is currently no dedicated international or national standard or regulation that spec-ifies how to assess post-fire residual material properties of natural stone (such as me-chanical strength or mineralogical transformation) in a standardized way. We have added this text to the introduction.
Comment 3: Page 4, line 178. Which of the cooling methods discussed in the literature have you selected for your study? Please add some explanation for the choice of methods and analyses in relation to the investigated case studies.
Response 3: The line (paragraph) in question provides context and background on previous studies and the motivation for this work. The detailed description of the methods used in this study is provided in the 3.2. Experimental procedures and settings section, where the selected procedures and their rationale are clearly explained.
Comment 4: Page 5, line 200 – “petrographically…”. Add references.
Response 4: The relevant reference is already properly cited at the end of the corresponding paragraph. (line 210)
Comment 5: Page 5, lines 212–213. Add references.
Response 5: Relevant references have been added to support the statements on lines 212–213.
Comment 6: Page 5, line 223. “Marlstone is characterized by low capillary rise”. Do you mean capillary absorption? Please clarify or justify this statement.
Response 6: The wording has been corrected; the intended term is “capillary absorption,” not “capillary rise.”
Comment 7: Page 6, line 233. Why should rapid heating and cooling occur during a fire? This concept requires clearer explanation.
Response 7: The description of rapid heating and cooling during fire exposure is based on published literature. To improve clarity for the reader, the relevant part of the manuscript has been supported with the appropriate reference.
Comment 8: Page 6, lines 235–238. Please add references for this sentence.
Response 8: Relevant references have been added to support the statements on lines 235–238.
Comment 9: Page 6, line 244. Including a figure showing the macroscopic appearance of the rock would be useful.
Response 9: A figure showing the macroscopic appearance of the rock was not available for this study. The description in the text provides the relevant information on the rock's characteristics.
Comment 10: Tables 1 and 2. These tables could be moved to the Supplementary Materials. In the text, clearly indicate which sample codes belong to Group 1 and Group 2.
Response 10: The sample groups are already clearly indicated in Tables 1 and 2 through the sample IDs (M1_x for Group 1 and M2_x for Group 2), so the group assignment is sufficiently clear. We have chosen to keep these tables in the main text, as moving them to the Supplementary Materials is unnecessary for this study and may reduce accessibility for readers.
Comment 11: It is likely that the last part of the previous paragraph should be moved to Section 3.1, where the samples used for the analyses are described. The geological formation should also be specified
Response 11: The text has been moved as suggested. Short description of geological formation was incorporated in the text.
Comment 12: Page 8, line 280. The description of sample group M3 is missing.
Response 12: The text was corrected as there are only two groups of samples. Using the word “three” was a mistake.
Comment 13: Methods section. The description of the methods is lengthy and discursive. It is important to be more concise and focus on the purpose of each method. Detailed explanations of the working principles are unnecessary; instead, add bibliographic references (for example, in the section on CIELab).
Response 13: The Methods section was written to provide sufficient detail for reproducibility and to clarify the experimental setup. To address your suggestion, we have reviewed the section to ensure that each method’s purpose is clear and that excessive details of working principles are avoided where bibliographic references can be provided. The CIELab description has been slightly shortened.
Comment 14: For colour measurements, was a colorimeter used? Please clarify.
Response 14: Colour measurements were performed using a Canon EOS 60D camera, as described in the manuscript; no colorimeter was used. The CIELab values were determined from the captured images, with four regions of interest per sample. We have added an explanation to the text.
Comment 15: The sentence “In general, reflectance spectroscopy refers to a broad range of techniques that examine and record how electromagnetic radiation interacts with matter” is unclear.
Response 15: The sentence was indeed unclear and unnecessary. We have removed the sentence as the rest of the text is sufficiently clear.
Comment 16: In the methods, it is not specified how Young’s modulus was measured.
Response 16: Young’s modulus was determined from the stress–strain data obtained during uniaxial compression tests using the LabTest 4.100.SP1 machine, as described in the manuscript. The modulus was calculated in the linear elastic region of the stress–strain curve, following standard procedures. As this approach is widely used, we consider the description in the Methods section sufficient for reproducibility.
Comment 17: The petrographic description of samples subjected to thermal cycles is unclear. Are the changes described in the discussion (lines 505–520, p. 19) those observed in thin sections?
Response 17: The text was corrected to clearly state which changes were observed in our study
Comment 18: Page 21, lines 550–574. Please summarise these results. The reason for using this technique is unclear. It is difficult to identify structural changes in rocks with this method. Are there bibliographic references supporting the use of this technique for this type of analysis?
Response 18: We have modified the text stating why this method was used. The supporting citation forusing this method is included in the text.
Comment 19: Section 4.4 – Elemental concentrations analysis. These results were obtained by XRF, correct? To improve clarity, specify this in the section title.
Response 19: The section title has been modified
Comment 20: In Table 11, samples from Group M2 are not included.
Response 20: We have added text explaining, that only Group M1 samples were used for this analysis and why.
Comment 21: At 1100 °C, it is stated that calcite is no longer present according to petrographic observation, which is also confirmed by the hydrochloric acid test, whereas XRF shows an increase in Ca concentration. How can this be explained?
Response 21: We have added an explanation to the text.
Comment 22: How were the samples prepared for XRF analysis? Please add this information to the Methods section.
Response 22: We have added the description to the text.
Comment 23: Colour difference (ΔE*). For Group 1, it is unusual that ΔE* is lower at 1100 °C. Why does this trend occur? Could it be related to colour heterogeneity on the sample surface?
Response 23: The observed ΔE* values for Group 1 at 1100 °C reflect the actual measurements obtained from the sample surfaces. No specific trend of colour change with temperature is assumed, and the results are reported as measured. We have added a discussion on the potential correlation between colour changes and mineralogical transformations, and have also highlighted the possible influence of the natural heterogeneity of marlstone samples on the observed results
Comment 24: Conclusions. The petrographic results are not discussed in conclusions. For future analyses, it is also recommended to include the determination of the material’s physical properties.
Response 24: Our petrographic study confirmed a change in the mineralogical composition of the rocks, specifically a change from CaCO3 to CaO and a transition from iron oxyhydroxides (limonite and goethite) to hematite. Changes in mineralogical and structural composition were also confirmed using reflectance spectrometry. However, given the nature of the material studied, it would be appropriate to use additional methods (e.g., differential thermal analysis or electron microscopy) for a more detailed assessment of the mineralogical changes in the future. We have added explanation and suggestion for future research to the Conclusions.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript “Experimental assessment of post-fire residual material properties of marlstone” presents an interesting case study focused on the analysis of the mechanical properties of sandstones and marlstones used in Romanesque and Gothic architecture in Central Europe. The paper is well structured, methodologically sound, and overall solid.
Nevertheless, it is suggested to further strengthen the introduction by increasing the number of references to previous studies in which petrographic analyses of building stones from historic buildings and structures have been used to investigate material provenance, construction practices, and conservation-related issues. This would allow the proposed research to be better framed within the broader context of architectural stone studies and heritage science, as the suggested ones
Girotto C., Dilaria S., Previato C., Bonetto J., Mazzoli C. The Use of Stone Resources in the Roman Architecture of Oderzo (Treviso, Italy). Heritage 2025, 8(2), 44.
Sanz-Arauz D., Rodríguez-Escalante M., del Río-Calleja B., López-Andrés S. Characterization, Analysis, and Investigation of the Provenance of the Stone Construction Materials of the Vera Cruz Church (Segovia, Spain). Minerals 2024, 14(2), 178.
Martínez-Torres et al. Upper Cretaceous Limestones as Stone Resources for the Monuments of Oviedo (Asturias, NW Spain). Geoheritage 2022, 14:30.
Author Response
We sincerely thank the reviewer for the insightful comments and constructive suggestions, which have greatly contributed to improving the clarity, quality, and overall readability of the manuscript. We have carefully considered all the remarks and have revised the text accordingly to address the points raised
Comment 1: The manuscript “Experimental assessment of post-fire residual material properties of marlstone” presents an interesting case study focused on the analysis of the mechanical properties of sandstones and marlstones used in Romanesque and Gothic architecture in Central Europe. The paper is well structured, methodologically sound, and overall solid.
Nevertheless, it is suggested to further strengthen the introduction by increasing the number of references to previous studies in which petrographic analyses of building stones from historic buildings and structures have been used to investigate material provenance, construction practices, and conservation-related issues. This would allow the proposed research to be better framed within the broader context of architectural stone studies and heritage science, as the suggested ones
- Girotto C., Dilaria S., Previato C., Bonetto J., Mazzoli C. The Use of Stone Resources in the Roman Architecture of Oderzo (Treviso, Italy). Heritage 2025, 8(2), 44.
- Sanz-Arauz D., Rodríguez-Escalante M., del Río-Calleja B., López-Andrés S. Characterization, Analysis, and Investigation of the Provenance of the Stone Construction Materials of the Vera Cruz Church (Segovia, Spain). Minerals 2024, 14(2), 178.
- Martínez-Torres et al. Upper Cretaceous Limestones as Stone Resources for the Monuments of Oviedo (Asturias, NW Spain). Geoheritage 2022, 14:30.
Response 1: References have been added to the manuscript to provide additional context regarding petrographic analyses of historic building stones.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe comments have been addressed one by one.
