Chloride Penetration Resistance of a Ternary Blend Lightweight Concrete Bridge Deck

Abstract

In 2010, the Tennessee Department of Transportation (TDOT) launched a bridge rehabilitation project to rerate all truss bridges with gusset plate connections due to the federal mandate after the Minneapolis bridge collapse in 2005. One bridge that needed to be renovated was the Hurricane Bridge in Dekalb County, Tennessee. To provide a durable bridge deck and meet the latest highway loading specifications, TDOT used a Class L ternary (sand-lightweight ternary) mix instead of their standard Class D (normal weight nonternary) bridge deck mix. While placing a section of the deck, TDOT would cast cylinders to send to the University of Tennessee for rapid chloride penetration (RCP), surface resistivity (SR), and compressive strength testing. Previous RCP and SR testing of the TDOT Class D mix found that the mix provides poor to moderate chloride ion penetration resistance. Research reported herein supports the use of the TDOT Class L ternary mix as an alternative to the TDOT Class D mix in order to increase bridge deck durability. The results of the Class L ternary mix cylinder testing show a decrease in chloride ion penetration, an increase in surface resistivity, higher compressive strengths, and a higher correlation between SR and RCP than Class D cylinders.