I bought this in order to clean up my untidy pointing, ie mortar stains on bricks and concrete patio slabs. There was also considerable leaching. I chose this because it claims to be more environmentally friendly and safer to apply than the acid-based ones. My conclusion is that is mildly effective, especially on concrete slabs, though more than one application was needed. Had very little effect on mortar-stained bricks, even with scrubbing. You do need to follow the instructions regarding washing off the product before it dries in order to avoid a bleaching effect on concrete.