The Washington State Department of Transportation will be conducting experimental field testing of several selected polymer concrete thin overlays over a ten-year period. The polymer concrete material is manufactured by private industry firms and installed on selected bridge decks under standard WSDOT construction contracts. Approximately 14 bridges will be involved in the experiment.
The Snake River Bridge at Clarkston, Washington, Bridge No. 12/915, is the first bridge of the 14 to receive a thin overlay. The polymer concrete used is Flexogrid by Polycarb. The deck was repaired and overlaid in June of 1986.
Work on the thin overlay began on June 8 and was completed on June 20. A total of 6.477 S.Y. of overlay was involved. Traffic was accommodated at all times on the portion of the bridge not being overlaid. Construction progressed relatively smoothly per the inspector's report. The material permitted the contractor flexibility in the rate of installation and in starting and stopping the work. Width of installation was varied to accommodate temporary traffic lanes.
Pavement skid tests and bond tests all proved satisfactory. Ninety-one percent of the resistivity tests exceeded the minimum required by the specifications. The majority of the test points that did not meet the minimum specified occurred at the beginning of the work, where the contractor attempted to apply the material with spray equipment that apparently did not provide accurate proportionate mix of the epoxy components. Subsequent tests and reports will compare delamination, half-cell, chloride content, and rutting values to the original deck survey values.