Brick and Concrete Cleaner
Many chemicals can be applied to concrete masonry without appreciable injury to the surface, but strong acids or chemicals with a strong acid reaction should definitely be avoided. Even weak acid should be used only as a last resort as it dissolves the cement matrix of the masonry, beginning at the surface. This leaves the face more porous so that it absorbs more water and exposes more aggregate, thereby changing the colour and texture of the masonry. The general procedure is to thoroughly wet the masonry surface, spray or brush a minimum amount of chemical, allow it to act for 1 to 5 minutes and then scrub. Wash it off using one of these methods: Pressure Washing, Water Washing & steam cleaning.