Cem-Kote CW Plus is a one-component (add water only), Portland cement based coating (slurry) containing silica-based materials. Under water pressure (negative or positive), the soluble silicate penetrates (due to osmotic pressure) into the substrate, where it reacts with lime and forms insoluble calcium silicate crystals which "plug" the capillary pores and waterproofs the concrete while allowing water vapor to pass.