One method of cleaning and whitening cement revolves around the use of acid to remove all debris and the concrete sealant. Removing the sealant reveals the untouched cement below, leaving the area clean, white and looking new. Several types of acid are appropriate for this process, including muriatic, sulfamic and phosphoric. Diluted with water, spray the acid solution over clean cement in an even manner. The acid bubbles and boils, removing the surface of the cement until rinsed away with plain water. This cleaning and whitening process requires resealing of the entire area but provides a fresh start for the cement.
Tri-sodium phosphate is a readily available chemical for cleaning and whitening cement. Power washing is a common method for cleaning cement but does not always completely whiten the area. Even with high-psi usage, dull film may remain. With the addition of tri-sodium phosphate to the pressure-washing fluid tank, the cement will whiten and brighten. Spray on the chemical and allow it to sit for up to 30 minutes before rinsing away with clean water. For severe discoloration of cement, add sodium hypochlorite along with the tri-sodium phosphate for an additional punch of cleaning. These chemicals are not environmentally friendly. Cover grass and other vegetation before using.
Cholorine Bleach and Degreaser
For cleaning and whitening of cement, a two-step process may be in order. Everyday dish soap contains degreasing agents. When mixed with a bit of water, the suds break down grease, oil, grime and dirt on cement. Pour the mixture directly onto the concrete and scrub with a push broom. The soap rinses away with water. A second wash using chlorine bleach and water will whiten the cement. As the chlorine sinks in, it whitens the area. Use a push broom for the bleach as well to ensure the mixture gets into all the nooks and crannies of the cement area.
Just as ammonia whitens and brightens kitchen and bathroom floors, the cleaner will whiten and clean cement. Mix approximately 1 cup of ammonia with a 1/2 gallon of water. Add a small amount of all-purpose household cleaner. Ensure the cleaner does not contain bleach. Use a push broom or sponge mop to apply to the cement and allow to stand for several minutes. Water rinsing is necessary.