Time-dependent behavior of full-scale self-consolidating concrete precast prestressed girders

As a part of an ongoing study at the University of Minnesota, self-consolidating concrete (SCC) has been developed successfully with locally available materials from two precast concrete plants for use in precast prestressed bridge girders in the State of Minnesota. Four SCC mixes (i.e., two mixes per plant) were designed, evaluated, and used to cast four SCC precast prestressed bridge girders. Variations in the SCC mixes included cementitious materials (ASTM Type I and Type III cement, and Class C fly ash), natural gravel and crushed stone as coarse aggregate, and several admixtures. In addition to SCC girders, a conventional concrete girder was cast simultaneously on the same precasting bed for each plant. The girders were instrumented to monitor both short-term and long-term performance, which included transfer length, camber, and prestress losses. In addition, companion cylinders were cast to monitor compressive strength and modulus of elasticity over time. The test results indicate that the overall performance of the SCC girders was comparable to that of conventional concrete girders and could be predicted using existing design equations.