Polytek's Concrete Crack Fill - Thin is a two-part epoxy adhesive that penetrates deep into small cracks to provide protection. It has a low viscosity that allows it to be easily dispensed from a caulking gun without mixing. The material cures in 2 hours, is waterproof and flexible, and can be sanded, drilled or tapped after curing. It is suitable for filling hairline cracks, divots and impact marks in concrete.