weber.cem keycoat is a single-component polymer-modified cementitious bonding aid and steel reinforcement primer. It requires only the addition of clean water to produce a bonding slurry for the weber.cem range of repair mortars cementitious screeds renders and new to old concrete. This product contains migrating corrosion inhibitor to protect the steel reinforcement within the repair zone and reduce the rate of corrosion within the vicinity of the repair.