Techniseal® HD Paver Prep is specially formulated to dissolve efflorescence (whitish salt) and remove ground-in dirt (traffic marks, etc.) on pavers, slabs and retaining walls made of concrete. Containing no hydrochloric (muriatic) acid, it works deep without discoloring or damaging the surface. It brightens up colors, cleans evenly and enables sealers to better penetrate the surface of the material. North America compliant except for SCAQMD (LA, Orange, Riverside and San Bernardino Counties, CA).