Applicability of standard equations for predicting mechanical properties of scc

Self-consolidating concrete (SCC) is being implemented throughout the US. Some advantages of SCC include its ease of placement, reduced labor requirements for placing the material, reduced noise when placing, and its improved finish quality. Clearly there are benefits of using this material. However, the AASHTO LRFD specifications were developed based on material characteristics of conventional, normal strength concretes. Because of this, engineers and designers are reluctant to specify and use SCC for bridge applications, possibly making the potential benefits of this material underutilized. This research investigated compressive strength development, modulus of elasticity (MOE), modulus of rupture (MOR), and splitting tensile strength (STS) of SCC mixtures specifically designed for precast, prestressed, concrete bridge girders. The experimental program included two target 16-hour compressive strength levels and two coarse aggregate types (river gravel and crushed limestone) with varying volume fractions. The measured mechanical properties for the SCC mixtures were compared with the results of conventional concrete (CC) mixtures of similar release strengths, as well as the estimated values from the 2006 AASHTO LRFD prediction equations. Results indicate that the AASHTO equations either predict the mechanical properties of SCC fairly well or underestimate the properties of SCC.