Comparative study of laser-induced spalling behavior on concrete blocks with different water/binder ratios

To investigate the effect of the water/binder (W/B) ratio on laser-induced explosive spalling, laser scabbling experiments on concrete blocks were performed. The level of porosity in concrete, which is significantly influenced by the W/B ratio, affects the possibility of laser-induced explosive spalling driven by the rapid increase in pore pressure. Two types of concrete blocks were prepared with W/B ratios of 34.3 % and 60 %. A 5 kW laser coupled with an optical fiber was used to induce spalling in both concretes. The low-W/B concretes exhibited vigorous explosive spalling, while the high-W/B concretes showed less vigorous explosions or more pronounced vitrification. These findings demonstrate a distinct difference in laser-induced spalling behavior between low- and high-W/B concretes.