High-Early Strength Concrete for Rapid Bridge Deck Repair and Rehabilitation

Abstract

With an ever-increasing demand for bridge deck rehabilitation due to aging infrastructure and increasing traffic demands, bridge deck overlays are used as a viable economic and environmentally cost-effective solution for prolonging the service life of a bridge. These overlays typically share the same characteristic of fast-setting and high-early strength development to minimize traffic disruptions, however, current methods do not typically address rehabilitation at varying levels of deterioration or make use of expensive non-cementitious materials. This research investigated the use of belitic calcium sulfoaluminate (CSA) cement to determine highest performing mix designs and surface preparations, to aid in the implementation and identification of a cement-based alternative repair material. An extensive experimental testing program resulted in nine slab specimens that were cast, overlayed, bond tested, and evaluated to identify the best performing BCSA mix designs, surface preparations, and admixtures. Various overlay and substrate laboratory specimens were also tested to identify fresh and hardened concrete properties which were essential in understanding overlay-to-substrate compatibility for long-lasting repairs. The results of the testing program indicate that BCSA cements show high potential to be successful in accelerated overlay applications. BCSA cements tested in this studied exhibited fast-setting and rapid strength gain, reaching minimum opening strength thresholds from various state agencies within a day. When compared to the conventional portland cement substrate cast in this study, BCSA cements exhibited much lower drying shrinkage, and no cracks were observed in the overlays cast. Polymer modified BCSA cements exhibited exceptional bond strengths higher than performance criteria specified for ultra-high-performance overlays by Caltrans (>400 psi) and comparable to bond strength requirements for polyester polymer concrete (500 psi). Bond testing results indicate that polymer modifying BCSA cements leads to significant increases in bond strength.