Burlington Northern Railroad Overcrossing Bridge, Microsilica Modified Concrete Overlay. Bridge No. 5/718W. Post Construction Report

摘要

Washington State has approximately 700 bridge decks that may require a latex modified concrete (LMC) overlay in the next 12 to 15 years. The microsilica concrete overlay is seen as a possible alternative to the increasingly expensive latex modified concrete. A microsilica modified concrete overlay was placed on Bridge 5/718W in Skagit County. The bridge is a concrete box girder structure with 8,100 square feet of deck area. The ADT on this bridge is 9,150 vehicles per day. The minimum overlay thickness was 1 1/2 inches. Superplasticizer was added to the mix. The concrete was mixed in a conventional batch plant with the technical representative from the microsilica supplier providing assistance. The microsilica modified concrete overlay was finished and cured as prescribed by WSDOT's specification for LMC overlays.