Efficacy of a Ternary Blend Mixture in Improving Bridge Deck Concrete Durability in Tennessee

Abstract

Studies related to the durability of bridge deck concrete in the state of Tennessee have been ongoing at the University of Tennessee for the past decade. The most recent phase of this research began in the fall of 2009 with a focus on developing a criteria and methodology to assess the durability of bridge deck concrete in Tennessee. The concrete’s resistance to chloride ion penetration was used to evaluate durability. This resistance was measured by two test methods: the surface resistivity (SR) test and the rapid chloride ion penetration (RCP) test. Current guidelines set forth by the Tennessee Department of Transportation (TDOT) require that a Class D concrete mixture be placed on all bridge deck applications. The SR and RCP tests have been performed on Class D concrete cylinders from various bridge deck placements across the state for the past 2.5 years. The Class D mixture consists of 75% cement and 25% fly ash (generally Class F). Results indicate that the current concrete mixture fails to adequately resist chloride ion penetration at satisfactory levels.