High-strength concrete applications to prestressed bridge girders

This paper focuses on recent research conducted at the University of Minnesota on applications of high-strength concrete to prestressed bridge girders. The research comprised production of high-strength concrete with a variety of cementitious materials (Portland cement, microsilica and fly ash) in different proportions, and made with six different types of coarse aggregate. Some specimens were moist-cured in saturated limewater at 73°F (23°C); others were heat-cured in an environmental chamber at 120° or 150°F (50° or 65°C) to simulate the accelerated curing technique used by precast/prestressed plants. The hardened concrete specimens were tested for compressive strength, modulus of elasticity, tensile strength, modulus of rupture, shrinkage, creep, absorption potential (as an indicator of permeability) and freeze-thaw durability. In addition, a parametric study was conducted to determine the viability of using high-strength concrete in prestressed bridge girders. Two long span prestressed bridge girders have been constructed to investigate transfer lengths, prestress losses, fatigue performance, shear and ultimate strength of girders cast with high-strength concrete.