**5. Conclusions**

Laser scabbling, which advances beyond the limitations of the previous methods, might be one of the better options for scabbling cement-based materials. Understanding the effects of silica sand on the composition of materials used in scabbling is essential to study. A pulsed laser was used in this study with a power density of 1.45 × 10<sup>5</sup> W/mm2. Experiments on cement mortar samples CM0.2, CM0.4, CM0.6, CM0.8, and CM1.5 were conducted to investigate the effect of silica sand proportion in laser scabbling on cement mortar. Furthermore, SEM/EDX analysis explored changes in the microstructure and chemical composition of cement-based materials under the influence of laser. The main observations and results of this study are summarized as follows:


Due to the laboratory scale, the use of silica sand and cement types was limited in this study. On the other hand, laser scabbling on cement-based material is a work that is dependent on specific silica sand and cement types in specific locations. So that, in future work, the various types of silica sand and cement in making cement mortar is needed to investigate. Furthermore, experiments are required to determine the effects of silica sand proportion on the influence of volume removal, the surface temperature of samples scabble using a high-power density laser. Furthermore, the optimization of laser parameters is considered to achieve the optimal result in depth penetration and volume removal.

**Author Contributions:** D.L. and Y.S. conceived and designed the experiment; D.L. and Y.S. performed the experiments; D.L., Y.S. and T.-V.H. analyzed the data; D.L., Y.S. and T.-V.H. wrote the paper. All authors have read and agreed to published version of the manuscript.

**Funding:** The research described herein was sponsored by the National Research Foundation of Korea (NRF) gran<sup>t</sup> funded by the Korean governmen<sup>t</sup> (MSIT; Ministry of Science and ICT) (No. 2019R1A2C1089644) and by the Korea Innovation Foundation gran<sup>t</sup> funded by the Korea governmen<sup>t</sup> (MSIT) (No. 2020-DD-SB-0159). This work was also supported by the research gran<sup>t</sup> of the Kongju National University in 2021.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data is contained within the article.

**Conflicts of Interest:** The authors declare no conflict of interest.
