GUIDELINES FOR THE THICKNESS DESIGN OF BONDED WHITETOPPING PAVEMENT IN THE STATE OF COLORADO

This report summarizes the development of procedures for the thickness design of bonded whitetopping pavement in the state of Colorado. Included in this report is an overview of the selected sites, design parameters, instrumentation, data acquisition and analysis. The parameters studied included joint spacing, concrete flexural strength, asphalt thickness, subgrade modulus of elasticity, concrete and asphalt modulus of elasticity, design equivalent single axle load (ESAL) and temperature gradient. Equations were developed to predict the critical stresses and asphalt strains. A mechanistic design procedure is described which allows the evaluation of trial whitetopping thickness and joint spacing. A modified procedure was also developed incorporating an empirical approach based on the number of ESALs. Based on this research a minimum subgrade modulus of 150 pci is required along with an asphalt thickness of 5 in. (12.7 cm). As with the AASHTO procedure, the method is not too sensitive to the number of ESALs.