How to Treat Old Concrete Masonry Unit Buildings

Clean the concrete surface completely, ensuring that all surface contaminants have been removed. Carbon crust, mildew, salts, bird droppings and other debris must be scraped off the concrete masonry to prevent interference with the consolidation treatment. Scrape debris off, using a putty knife or small chisel.

Obtain concrete consolidation treatment in liquid form from concrete suppliers or distributors. Brush the treatment material onto the concrete masonry surface, using a high-quality paintbrush or roller to saturate the surface. Apply three saturating applications in rapid succession, at five- to 15-minute intervals. After the third application, allow the consolidation treatment material to dry for 20 minutes to an hour.

Apply additional layers of consolidation treatment material until excess remains on the concrete masonry surface for 60 minutes. This typically takes two or three rounds of successive applications.

Pour mineral spirits into a garden sprayer and flush the concrete masonry surface. Allow the mineral spirits to air dry on the masonry. If you see evidence of the consolidation treatment material, spray it with more mineral spirits until the area runs clear of the treatment.

Allow two to three weeks of curing time before applying additional consolidation treatments to the concrete masonry building.