Performance of material removal in pulsed laser irradiation on concrete

Nguyen, P. L.; 大道 博行; 松永 幸大; 山田 知典; 西村 昭彦  ; 河内 哲哉*

Nguyen, P. L.; Daido, Hiroyuki; Matsunaga, Yukihiro; Yamada, Tomonori; Nishimura, Akihiko; Kawachi, Tetsuya*

Nowadays, laser processing for removing defects in concrete infrastructure can open the possibility of industrial application for the maintenance technique of aging tunnel wall in Japan. Pulsed laser processing of material is an important part of the laser technical application, which include laser drilling, welding, cutting, etc. Advantages include a non-contact processing, a low heat input into the material, accuracy and consistency. An understanding of mechanisms of ejected molten material and characteristic of hole drilled is necessary to enhance the performance for pulsed laser irradiation on concrete. For requirement of small apparatus as working in the tunnel transportation, the YLR-150/1500-QCW (Quasi continuous wave) fiber laser having compact dimensions was used in this experiment, allowing for a maximum peak power of 1.5 kW and average power of 150 W, operating at 1070 nm. The laser beam was focused with a lens, giving a beam diameter of 1.0 mm and 2.0 mm on the surface concrete.