Commonly found in commercial, industrial, and educational settings such as classrooms, work areas, basements, and stairwells, concrete masonry units (CMU) and concrete block are found throughout the world. CMU block is frequently painted for aesthetics, but coatings may also be chosen for other more functional reasons such as moisture resistance or to provide an anti-graffiti barrier. If staining or a coating must be removed, a method of surface prep must be considered that preserves the structural integrity of the block.
CMU block needs to be regularly maintained in order to keep their clean appearance and increase their longevity. Over time, if they are not properly maintained, they can develop cracks and fissures, making them look unkempt and potentially leading to serious structural issues. Regular maintenance of these blocks, including paint removal and repainting, helps to prevent these problems and extends their life.
One of the most important steps in maintaining CMU blocks, but also one of the most overlooked, is surface preparation of the blocks prior to repainting. It is crucial to remove old, flaking, and peeling paint before applying a new coat of paint. If the old paint is not properly removed, it can interfere with adhesion of the new coating, as paint that is left on the surface may cause new coatings to peel, flake, and fail prematurely.
However, it’s important to keep in mind that not all paint removal methods are suitable for CMU blocks. Some methods can damage the concrete, negatively affecting both its appearance and the structural integrity of the blocks. For example, ordinary abrasive blasting can be too aggressive and overly erode the surface, as well as weakening the concrete. Alternatively, chemical strippers, while able to dissolve the paint through multiple applications, can ultimately be too harsh on the concrete, causing discoloration, PH imbalances, and creating an uneven surface that is not suitable for applying new paint.
Many contractors turn to Sponge Media blasting for these paint removal applications. Unlike ordinary abrasive blasting, Sponge Blasting is aggressive enough to remove the paint, but gentle enough to prevent damage to the CMU blocks.
Further, Sponge Media blasting is often chosen for these projects due to its low-dust, low-rebound characteristics. As CMU blocks are often found in public spaces, such as college campuses, educational buildings, and commercial buildings, these paint removal projects are often performed within close proximity to students, faculty, and nearby pedestrians. Sponge Blasting allows plants and facilities to remove old paint with minimal containment, and without needing to shut down and stop production.
