The Iowa Department of Transportation used a high molecular weight methacrylate (HMWM) resin to seal a 3,340-ft x 64-ft bridge deck in October 1986. The sealing was necessary to prevent de-icing salt brine from entering a substantial number of transverse cracks that coincided with the epoxy-coated top steel and unprotected bottom steel. HMWM resin is a three-component product composed of a monomer, a cumene hydroperoxide initiator, and a cobalt naphthenate promoter. The HMWM was applied with a dual spray-bar system and flat-fan nozzles. Initiated monomer delivered through one spray bar was mixed in the air with promoted monomer from the other spray bar. The application rate averaged 0.956 Gal/100 sq ft for the tined textured driving lanes. Dry sand was broadcast on the surface at an average coverage of0.58 Lb/sq yd to maintain friction. Coring showed that the HMWM resin penetrated the cracks more than 2 in. deep. Testing of the treated deck yielded friction numbers averaging 33, with a treaded tire compared to 36 prior to treatment. An inspection soon after treatment found five leaky cracks in one of the 15 spans. One inspection during a steady rain showed no leakage, but leakage from numerous cracks occurred during a subsequent rain. A second HMWM application was made on two spans to determine if a double application would prevent leakage. This evaluation has not been completed.
Abstract