An increasing number of highway engineers are choosing polymer concrete for concrete bridge deck rehabilitation, finding that its advantages as an overlay material justify its high cost. A polymer concrete overlay not only improves the abrasion and skid resistance of the deck surface, it also protects against corrosion of steel reinforcement. Containing no portland cement, polymer concrete is impermeable to water, deicing salts, and chemicals that can accelerate corrosion. A polymer concrete overlay also minimizes traffic disruption. It's generally applied at a total thickness of only one-half to three-quarter inch and cures in as little as 2 hours. In some cases, workers can place the overlay at night then open it to traffic the next day.
The two main components of polymer concrete, resin binder and aggregate, both contribute to the material's durability and protective qualities. Choose these carefully. Mixing the binder components at the ratios specified by the supplier is critical. Failure to mix the components completely can result in a nonuniform overlay with soft and hard areas. The polymer concrete overlay can be applied in two different ways. In the premixed or slurry method, the binder components and aggregate are premixed to form a polymer concrete that is then spread over the deck at the required thickness. The broom-and-seed or build-up method involves placing the overlay in successive layers, allowing each layer to cure before applying the next layer.