GE Concrete Silicone 2 Sealant, Lt. Gray, 10.1oz. From the #1 Silicone Brand, Concrete Silicone 2 sealantisahigh-performance, 100%siliconeand100% waterproofsealant for concrete, mortar and stone projects. This 30-minute rain-ready formula is light gray in color and offers permanent flexibility and excellent durability with 10-year mold-free product protection to help resist mold and mildew growth.Backed by a lifetime guarantee.