In abrasive blasting, what is used to remove mortar or stains from masonry surfaces?

• A. Water and brush
• B. Sand and water
• C. Abrasive material under air pressure
• D. Chemical cleaners

Answer: (C)

Abrasive blasting removes mortar and stains by a stream of abrasive particles propelled at high speed with compressed air. The physical impact of these media on the masonry surface shears away the unwanted material, making it effective for cleaning and restoring surfaces. This mechanical action is what differentiates it from just washing with water and a brush or using chemical cleaners, which rely on dissolution or scrubbing rather than blasting media. The abrasive material can be media like sand or other hard particles, chosen based on the surface and the level of cleaning needed, and the air pressure controls how aggressively the material acts.