Acoustic Emission Analysis of Fracture and Size Effect in Cementitious Mortars

Round 1

Reviewer 1 Report

The author investigated experimentally the size effect of quasi-brittle materials in Brazilian splitting tests using the AE technique. The effect of sample size and boundary condition on strength and fracture progress of cementitious mortar samples were studied and interesting results have been found. The paper is well organized, it is recommended the paper be accepted after minor revision. Some suggestions:

-In the Abstract and Conclusions, it is recommended to present some of the main results obtained in the study in quantitative terms.

- Page 3 line 96: the curing condition should better be given in this section.;

The size of the prisms seems to be strange to the reviewer, please confirm if this information is correct.

- Page 4 table 2: Is it a mistake that the thickness of the medium specimen is 47 mm? Or just due to the variation of the size of the mould.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

The authors submitted a manuscript on fracture and size effect in cementitious mortars bassed on AE technology and the following comments should be taken into account before publication.

-The novelty and engineering value of this work compared with existing literatures should be better stated in the introduction. Indeed, several references are given, but with limited details and discussion about the highlights and problems to be solved of the paper. It will be necessary to rewrite this section.

-Due to its inhomogeneous nature, concrete attenuates high frequency components and is usually inspected with AE sensors that have frequency of 60 kHz or lower(Reference: Advanced Structural Health monitoring of Concrete structures with the aid of acoustic emission). However, six piezoelectric broadband sensors with a 50 to 2000 kHz frequency range were used in your work. How did you consider the influence of frequency on test result? Please explain it.

-The authors should relate the AE amplitude and AE hits to the points on the Load-displacement diagram in Figure 6. The authors must add to the work the analysis of the results taking into account the Load-displacement diagrams of the Brazilian splitting test.The document loses a lot of interest without these diagrams.

-In Line 283 to Line 291, you explained the unsymmetrical nature of crack propagation by the compression surfaces not being fully parallel and the casting quality of specimens. Did the above two reasons affect the credibility of the experimental results? How did the unsymmetrical nature of crack propagatio affect the experimental results?

-Have you evaluated the accuracy of AE localization by breaking lead test? If not, how to make sure the FPZ you computed is accurate?

-The sensitivity of b-value analysis to AE amplitude attenuation has been mentioned in your paper. Therefore, does the size of specimen also have an effect because the propagation distance of AE elastic wave becomes longer with the increase of specimen diameter? Please explain it.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

The authors have already published another contribution in a conference that appears to be covering the same study [Deresse, N. E., Van Steen, C., Sarem, M., François, S., & Verstrynge, E. (2021). Acoustic emission-based damage monitoring to study fracture in cementitious mortars under fatigue loading. European NDT & CM 2021]. The approach also looks the same. The authors must highlight this and describe in detail the substantial differences between the two contributions and in the case of a continuation of the work, describe in detail what aspects were investigated and what results were obtained.

 

Section 1 must be improved. Authors should emphasize contribution and novelty, the introduction needs to clarify the motivation, challenges, contribution, objectives, and significance/implication.

 

Section 2 must be improved. Describe in detail the equipment used to make the measurements (Brazilian splitting test and AE sensors). Extract this data from the datasheet of the instrumentation manufacturer. To make reading the specifications of the instruments more immediate, you can insert them in a table, listing the instruments used and the specific characteristics for each.

 

Section 3 must be improved. The authors must improve the figures that are shown to describe the results obtained. I have added some specific suggestions.

 

Section 4 must be improved. The authors must improve the figures that are shown to describe the results obtained. I have added some specific suggestions.

 

Section 5 must be improved. Paragraphs are missing where the possible practical applications of the results of this study are reported. What these results can serve the people, it is necessary to insert possible uses of this study that justify their publication. They also lack the possible future goals of this work. Do the authors plan to continue their research on this topic?

 

 

59) Do not use abbreviation such as i.e. I have seen that you often use this abbreviation, so I will not repeat this advice again, it also applies to the other occurrences.

94-99) Add a photo of the three prisms preparaed.

99)Table 1 is the same in other publication (Acoustic emission based damage monitoring to study fracture in cementitious mortars under fatigue loading), verify if a copyright permission is needed

96-100) Make sure that the units of measurement used in the apper are consistent. For example: prisms dimensions (160 × 160 × 40 mm3) and Mortar composition in table 1 (Kg / m3). The unit are different. I will not repeat this advice again, it also applies to the other occurrences.

217) Figure 3 must be improved. Move the text next to the labels of the two figures (a and b) in the caption. Add in the caption the the meaning of the variables (B, …). Add the dimension of the samples.

217) Figure 4 must be improved. resize the text in the legend

227) Figure 5 must be improved. Move the text next to the labels of the two figures (a and b) in the caption. Add in the caption the the meaning of the variables (B, …). Add the dimension of the samples.

249) Figure 6 must be improved. Where is a map with location of the sensors? Ch-1 and Ch-3 are not introduced until now.

275) Figure 8 must be improved. Add a label to each subfigure and add an explanation in the caption

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

The authors addressed the reviewer's comments with attention and modified the paper consistently with the suggestions provided. The new version of the paper has improved both in the presentation that is now much more accessible even by a reader not expert in the sector, and in the contents that now appear much more incisive.

Minor revision

• Check the format of Figure caption
• In Figure refers to sensor using the format Ch-1, Ch-2, etc

Author Response

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Author Response File: Author Response.pdf