Improving the adobe material properties by laser material processing.

• Adobe is one of the main constituents of old heritage and current buildings in world. • Adobe is a sustainable, inexpensive and environmentally friendly material. • Novel strengthening and reinforcement methods of adobe material is necessary. • Laser shock process enhances mechanical properties of the adobe. • Laser treatment reduces water absorption of the adobe. • Microstructure analysis confirm improved integrity and homogeneity of adobe surface by laser treatment. Many of the old heritage buildings and even many current buildings in the world are made of adobe, which is a sustainable, inexpensive, and environmentally friendly material. The adobe buildings react harmoniously against gravity or lateral forces, but structural fractures and sudden forces such as natural disasters or moisture leakage are the main causes of making them vulnerable, especially against earthquakes. Strengthening and reinforcement of adobe materials have long been discussed, and techniques such as adding materials to adobe or plastering adobe walls have been used to increase its resistance. Here, laser shock processing operation is exploited to analyze the extent of change in mechanical strength and moisture resistance of adobe material and ultimately to test its applicability to heritage buildings. The distance between the focal point of the laser beam and the surface of the adobe is optimized while an optimum value is also obtained for laser intensity. Laser radiation increases the compressive strength and flexural strength of the adobe by 348% and 12%, with respect to the raw material, whereas no significant difference is observed in the tensile strength. Nevertheless, the hydrophobicity of the samples increases by upper defocus and increasing the defocus, improves the soil adhesion, and escalates the homogeneity and integrity of the surface. Microstructural analysis such as SEM, EDAX and XRD of raw, and laser-treated adobe material confirm these improvements and overall render laser treatments an interesting, beneficial candidate among adobe reinforcement techniques. [ABSTRACT FROM AUTHOR]