Influences of test conditions of sandblasting on replicability of abrasion pattern of concrete subjected to hydrodynamic action

To determine the most suitable test conditions for sandblasting to evaluate the abrasion resistance against hydrodynamic action, a series of abrasion tests using hardened cement pastes with different water-cement ratios were performed under multiple combinations of air pressure and distance of the blast gun from the surface of a specimen. It was confirmed that the sharpness at the bottom of an abraded part, which largely influences the stability of the determination of the abrasion level, did not depend on the air pressure or the distance. Also, it was revealed that the relative value of the abrasion depth of materials with different abrasion resistances varied depending on the combination of air pressure and distance. This result indicates that when concrete is worn by sandblasting, the concrete surface exhibits different abrasion patterns depending on the conditions of sandblasting because the abrasion resistance of mortar matrix is usually lower than that of coarse aggregate. From the aspect of replicability of the abrasion pattern of concrete surfaces confirmed in in-service structures where coarse aggregates protrude, the combination of an air pressure of 200 kPa and a distance of 50 mm was determined as the most suitable test condition for sandblasting, and the applicability of the determined test condition to the replication of the abrasion pattern was validated.