Rheometry for Concrete 3D Printing: A Review and an Experimental Comparison

Round 1

Reviewer 1 Report

A systematic review has been presented in this paper focusing on rheology characteristics of 3D concrete printing and followed by experiments. Since 3D concrete printing is an emerging construction method, this paper is recommended for publication. The reviewer suggests the following comments to improve the quality of the paper.

-Authors may consider adding a few figures on the real-world application of 3D printing in construction in the Introduction section.

-There are a lot of review papers published in recent years. Authors may need to clearly state the limitations of previous papers (details that are not focused) and what is new in this paper.

-The first half of the paper reviews the rheology characteristics, and standard and non-standard methods while the remaining part covers the experimental studies. There is less connectivity between Section 2 and Section 3. A couple of connecting sentences should be added at the end of Section 2.

- As mentioned in the above comment, authors may think of revisiting the title of the paper as it partly covers review and experimental work, therefore it may not be considered a complete review paper. The authors can clarify this. Further to support this, the summary and conclusions section majorly covers and highlights the results/conclusions from the experimental work.

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

1.      Title: The title suggests that only a literature review is provided in this work. However, an interesting experimental campaign is also presented in this study. The authors should reformulate the title in order to highlight both contributions of the present paper. For example, the title of this paper could be “Rheology measurement techniques and rheology characterization for 3D concrete printing processes: A literature review and new experimental test comparisons”.

2.       Section 1: The rheological behavior of 3D printed concrete was the main topic of many recent review papers, such as Saruhan et al. 2022 (DOI: 10.1016/j.conbuildmat.2022.127629), Rehman and Kim 2021 (DOI: 10.3390/ma14143800), Jiao et al. 2021 (DOI: 10.1016/j.cemconcomp.2021.104152), Biricik and Mardani (DOI: 10.1016/j.conbuildmat.2022.127688), etc. These works were not cited in the present paper. Based on the information revised in all these works, is the content of Section 2 original? Original contributions of the literature review section of this paper should be better highlighted in Section 1.

3.       At the end of Section 1, the authors should clearly present the existing gaps in the literature on the main topic of this paper. After that, the original contributions of the present work to the current state-of-the-art should be highlighted. For example, the authors should justify the research significance in Section 1 using the novelty aspects presented in Section 5 of this paper.

4.       Section 1: At the end of Section 1, the authors could briefly clarify the structure of this paper, stating the different topics addressed in the two main parts of the manuscript, i.e., main topics of the literature review presented in Section 2 and main topics of the experimental program presented in Sections 3 and 4.

5.       Section 1: Since this paper is too long, a flowchart should be added to Section 1 to summarize the structure of the present manuscript, as recommended in the previous comment.

6.       Section 1: Section numbering should be improved. For example, why did you add “Section 1.1”? Actually, there is no Section 1.2, Section 1.3, etc…

7.       Sections 1 and 2: It seems that the subsection “Rheology and process parameters for the material used in 3DCP” would fit better in the literature review section of the paper, i.e., Section 2.

8.       Section 2: The authors did not mention the review methodology used to select the papers revised in this literature review section (e.g., review strategies, keywords, databases, etc). The authors should indicate the criteria (e.g., journal, publication year, number of citations, main topics, etc) used to define whether a material is relevant to the review paper or not.

9.       Section 2: Please verify if you got the right to publish all copyrighted images presented in this section. When using images of papers published in previous literature, it is necessary to require a written permission from the copyright holder.

10.   Section 2: At the end of subsection 2.4, the authors could obtain new insights obtained from the revised data, in order to provide new information on this field. The original contributions derived from the information revised in Section 2 should be clearly highlighted in the abstract, introduction section and conclusion section.

11.   Section 3: In Section 3.1, the authors should better clarify the reasons for changing the nano clay dosage, based on descriptions of the basic properties of these admixtures.

12.   Section 3: nano clay percentages were provided in terms of mass (or volume) of cement? Binders? Composite?

13.   Section 3: Type of cement and sand should be stated.

14.   Section 3: Density of cement, aggregates, silica fume and other admixtures could be added.

15.   Section 3: In Figure 6, it would be interesting to organize real images of all tests indicated in Table 5.

16.   Section 3: Could you clearly identify mixes M0, M0.1, and M0.3 in Fig. 9?

17.   Section 4: Section 4.9, the authors could provide the average thickness and width of the different layers, and corresponding standard deviation (or coefficient of variation) before failure, in order to complement the buildability characterization.

18.   Section 5: Limitations of the experimental program of the present paper and recommendations for future studies should be added to this section.

19.   High-quality vector images should be provided in this manuscript, especially in Section 4.

20.   Consistency is an issue in this paper. For example, sometimes space was added between numbers and units (e.g., “25 mm”, “1.5 kPa”). Sometimes, space was not added between numbers and units (e.g., “300g”, “100g”) .

21.   There are some typo mistakes in this paper such as “again(high”, “30 ?m”, “M0,M0.1”, “M0.1. Highest for M0.3)”, “ratio mixes ( 0.23”, among others.

22.   There are some grammar and typo mistakes in this paper, such as: "stability failure is also can be seen frequently in 3DCP", "this simplified calculation may only valid", "the usage (...) may have many limitations", "main purpose of there study", "the tri-axial test is (...)commonly implement in geotechnical applications", “Screw rotational speed of 0.5 rev.s-1 and print speed of 48 mm.s-1 was selected”, among others.

Author Response

Please find attached

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The quality of the paper was improved, based on the corrections recommended by this reviewer. Then, this manuscript can be recommended for publication.