Review Reports

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

In this manuscript, the authors studied 3D printing of concrete, a promising technique used in construction that has attracted the attention of many researchers in recent years. In fact, the authors used graph theory for the optimization of the nozzle trajectory during the printing process. They proposed their trajectory optimization algorithm based on this theory, and verified its accuracy by experiments. The results showed a significant reduction in the idle strokes and the number of rise times of the nozzle trajectory, which reduced the construction or printing time and improved the quality of the concrete built structure. The proposed approach and results are very valuable for the progress of this technique and its application in concrete construction.

In the opinion of the reviewer, the paper can be recommended for publication in applied science Journal after revisions listed below:

- In the abstract it is recommended to specify the amount of reduction time recorded when the optimized toolpath is used compared to the usual nozzle path.

- In addition, it is recommended to specify the forming quality improvement based on how the quality is measured in this case.

- It is recommended in the introductory section to analyze the most recent contributions (2022) to see if someone else has already used the approach and if the investigation in this article is new.

- Last line (125) of the introduction section, add a comma to [20, 21] instead of  [20 21].

- The remark line 157, 158 ``There is a linear relationship between the number of line segments in the geometric figure and the number of elements in ``. How the problem is solved if there is fillet arcs in the corner for example or if the structure lead to a curve path?

- The number of points that discretize the lines (shown in Figure 4) how is it chosen. The distance between the points, if the number of points increases or decreases, how does it affect the result?

- Using CIMCO Edit 8, as in the milling process, it is easy to draw the sketch presenting the toolpath and using a virtual simulation, the post-processor can generate the G-code without needing any optimization using an algorithm because the sketch presented is very simple. However, algorithms are useful for new toolpaths for complex geometries. It is better to test the approach in a more complex geometry to see the effectiveness of the developed algorithm. 

- The nozzle or tool feed speed has a significant effect on the quality of the printed structure and the processing time. This parameter should be analyzed to see if the quality of the structure presented in Figure 10 could be improved by reducing the nozzle feed (speed).

- To validate the accuracy of using the algorithm, the authors should make a comparison with using the conventional method to generate the tool path and see the result.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The manuscript can be accepted in its updated form

Author Response

Thanks to the reviewer for taking time out of his busy schedule to review the manuscript, the comments given by the reviewer are a kind of affirmation for the authors. In the future, the authors will continue to refine the algorithm.