Acid Washing (Hydrochloric acid) is used to clean the surface of the concrete prior to application of sealers and paint systems. It cleans and removes light build ups of dust and any concrete salt build up from the surface. Salt build up is known as Efflorescence and looks like a white powder growing on the surface of the concrete. A light dose of acid generally consists of about 3-5% hydrochloric solution mixed with water.
Application of heavier doses can be used to remove the surface of the concrete to achieve an etched finish to reduce slip factors on exterior concrete. Heavier doses are often used to clean the surface of exposed pebble to increase colour.
The industry is moving away from the use of Hydrochloric acid due to the impact on the environment and its users.
Some paint manufactures request the use of Hydrochloric acid. We prefer to lightly grind the concrete which has much less impact on the environment.
Hydrochloric acid will rust and steel in close proximity so application in steel sheds is not recommended.
Cement based Grouting.
Grouting of stress cuts and decorative cuts is a basic must on all polished concrete and sealed concrete floors and patios.
We use cement based products in most situations as they provide the best visual colour match and look most natural.
As concrete dries and shrinks you will find that grout may crack away from the sides of the cuts. This is natural and no fault of the applicator. Some grouts will need to be replaced if the grout falls out of the cuts.
There are two styles of grouting. Recessed and flush.
Recessed is more commonly used as it hides any minor cracking and is more easily repaired.
Flush grouting is an option however is more costly to produce with results often not as good visually, as the recessed style.
Silicon based grouts are also available however used mainly in commercial situations. They can look fake or out of place in a residential situation.