Field Monitoring of Moisture Variations under Flexible Pavement

Abstract

A research program was conducted to study the behavior of different drainable base and subbase materials used by the Ohio Department of Transportation (ODOT). Two construction sites were chosen from this program to be built with different base course materials. Site I (ATB-90–19.56) consisted of ODOT 306 cement-treated, ODOT 308 asphalt-treated, and ODOT 304 sections. Site II (ATB-90-0.00) consisted of 307-NJ, 307-IA, 307-CE, ODOT 306 cement-treated, ODOT 304, and ODOT 308 asphalt-treated sections. Time domain reflectometry (TDR) probes were installed in subgrade and unbound subbase layers to provide continuous monitoring of the moisture variation in the pavement system. The laboratory calibration for TDR probes resulted in the development of suitable calibration coefficients for the studied materials and more accurate conversion of TDR field measurements to the in situ water content. The monitored moisture content variation was used to determine the drainage efficiency of different drainable base materials used by ODOT. The treated base materials (cement and asphalt) exhibited better drainage performance than did the other unbound materials.