| It is well accepted that moisture in pavement can cut down the pavement life. To examine potential damaging effects of moisture, water regimes in pavements need to be known. A permeable base layer provides improved pavement drainage and minimizes the frost action. The Ohio Department of Transportation (ODOT) has adopted several types of materials specifications for use as permeable bases: (a) Unbounded base materials including: 307-IA, 307-NJ, and 307-CE types, (b) Stabilized base materials including: Cement and Asphalt Treated base types. Nevertheless, the effectiveness of these permeable base materials has not been conclusively established in previous ODOT studies. This research was carried out to provide additional and separate field and laboratory test data to assess the field performance of the drainable bases in the asphalt pavement.; The main objective of this comprehensive research was to evaluate and monitor the environmental and structural field performances of the two-bounded ODOT permeable base materials and the four unbounded base course materials built on two test sites at Interstate Highway I-90 in Ashtabula County, Ohio. The monitoring was based on extensive field instrumentations, continues environmental data monitoring, construction documentation, non-destructive field testing, and extensive laboratory studies.; Statistical models have been developed through laboratory studies to describe the relation between materials bulk Electric Conductivity (EC) and the oven-dry water content for the studied soil materials. The range of the material bulk EC for safe TDR measurements was established for the investigated materials in this research. The safe limit for A-1b soils was found to be less than that recommended by the TDR manufacturer. In order to account for the materials with high bulk EC, the TDR probes were modified by coating the center rod of the probe using insulating tubes. The soil-dependent TDR calibration coefficients were determined for all materials present at the test sites. The calibration enabled for more accurate gravimetric water content measurements. Furthermore, a method was developed for determining the field dry density using the TDR measurements.; The EverCalc computer program was used to backcalculate the moduli of different pavement layers. Cement Treated was the stiffest base materials, followed by the Asphalt Treated, then ODOT 304, and finally the unbounded bases. According to the profiling measurements, there was no significant difference in the pavement surface roughness conditions after one year of constructing the Asphalt Treated, ODOT 304 and Cement Treated sections, at Phase I site.; The Coefficient of Variation (COV) in the subgrade water content can be used as a measure for assessing the drainage layer efficiency. Based on the COV results of the base materials, at Phase II site, the order of efficiency of the bases was as follows, starting from the less effective base materials: (a) 307-NJ, (b) 307-IA, (c) 307-CE and ODOT 304, (d) Asphalt Treated, and (e) Cement Treated. Asphalt Treated base had the least construction cost comparing with other base materials, including the typical ODOT 304. |
