SUBBASE PERMEABILITY AND PAVEMENT PERFORMANCE. FINAL REPORT

This project, constructed by the Pennsylvania Department of Transportation (PennDOT), demonstrated that open-graded, permeable subbase materials can be designed which provide constructability and pavement support as well as good internal drainage at a competitive cost. Five types of subbases, ranging from an impermeable cement stabilized material to a very permeable, uniformly-graded crushed aggregate, were evaluated during this seven-year research project. PennDOT's open-graded subbase is also discussed. Deflections in the 10-inch reinforced concrete pavement over the various subbase sections were measured with PennDOT's Falling Weight Deflectometer (FWD). These FWD measurements were used to determine the effects the various subbases had on pavement slab deflection, joint efficiency, and void formation. The effects of pavement temperature on slab deflections are also examined. Roughness measurements, made throughout the evaluation, are analyzed to determine the effects the various subbases had on short-term pavement performance.