National Concrete Pavement Technology Center

Project description

A fiber-reinforced super-workable concrete (FR-SWC) made with 0.5% micro-macro steel fibers and 5% calcium oxide (CaO)-based expansive agent was used for the new deck slab of Bridge A8509. The selected FR-SWC had a targeted slump flow of 20 in. at the casting location. Multiple trial batches were performed, in collaboration with the concrete supplier, to adjust the mixture composition to meet the targeted performance criteria. This was followed up by casting the fibrous concrete in a mock-up slab measuring 10 × 10 ft that was prepared to simulate the tight rebar and the roadway crown slope in the transverse direction. The results indicated the necessity to lower the concrete slump from the intended value for FR-SWC to hold the 2% crown slope of the bridge deck in the transverse direction. The final mixture that was selected following the trial batches and mock-up placement had a slump consistency of 8 ± 2 in. (FRC). Six sensor towers were installed in the slab within 18 ft to the East and West sides of the intermediate bent to monitor in-situ properties of the concrete.