| Idaho Transportation Department is searching for an alternative connection detail to be used in Accelerated Bridge Construction precast deck elements in order to reduce costs and construction time versus the currently used Ultra High Performance Concrete (UHPC) connections. High early-strength (HES) concrete with polypropylene fibers was selected as the material to be studied for this research project. The cost of using HES concrete is comparable to conventional concrete, with estimated cost savings ranging from $50,000 to $100,000 for a typical highway bridge construction, over the use of UHPC. Six different HES concrete mixes were tested for compressive strength, splitting tensile strength, and shrinkage. The optimum mix was tested with precast concrete segments for interface bond strength and headed bar pullout strength. Precast panels with the non-contact lap splice closure pour detail were tested in three-point and four-point bending. The optimum mix, HES-D, had a compressive and splitting tensile strength of 8,864 psi and 785 psi, respectively. This mix also had lower long-term shrinkage (522 microstrain) compared to UHPC. Bond strength between precast and HES-D was 612 psi, which is comparable to that of UHPC (712 psi). The average headed bar pullout strength was 12.5 kips and flexural beams had an average ultimate moment capacity of 147 kip-inch.
Key Words: High-early strength concrete; Precast bridge connections; Alternative bridge concrete; Accelerated Bridge Construction |