Constructability and Structural Performance of Self Consolidating Concrete in Cast-in-Place Bridge Construction

Many state departments of transportation (DOTs) don't allow using self consolidating concrete (SCC) especially in cast-in-place (CIP) bridge projects due to lack of construction guidelines and design specifications. As a part of NCHRP project 18-16, several SCC mixtures were developed to evaluate the constructability and structural performance of CIP bridge components made of SCC. A full-scale bridge pier specimen was constructed using three different SCC mixtures for footing, columns, and pier cap components. These mixtures have different proportions, aggregate sizes, and levels of flowability. Fresh and workability properties were tested at the plant and on site to evaluate the effect of delivery time and transportation on these properties. Different methods of placement, placement rates, and free-fall heights were used to evaluate their effects on the quality of the hardened concrete. The formed surface quality of all components of the pier specimen was evaluated according to the ACI 347R [1]. Results indicated adequate surface quality especially when SCC flows from bottom up during placement. The full-scale specimen was tested to evaluate the structural performance of SCC. Results indicated that current AASHTO LRFD provisions provide an adequate prediction of the flexural and shear strength of SCC components. All components were saw cut to evaluate the uniformity of coarse aggregate distribution and consolidation of concrete around reinforcement at different locations. Results indicated the stability of SCC mixtures even when the free-fall distance was 15 ft.