Impacts of aggregate base on roadway pavement performances

Three premature failures (related to weak, moisture-susceptible aggregate base) were investigated and the results are presented in the paper. Falling Weight Deflectometer (FWD) tests were conducted to determine the structural load bearing capacity. Laboratory tests were performed to evaluate the aggregate base’s susceptibility to moisture. One successful project that used crushed aggregate base as an interlayer to mitigate reflective cracking was studied. The crushed aggregate base interlayer performed well while other treatments failed. The weak and moisture-susceptible aggregate base, in conjunction with a thin, porous and brittle surface AC, caused premature failures for the three studied projects. It was theorized that the weak base deformed under the traffic load, and this cracked the brittle/thin surface mix. FWD test results for all three projects yielded much higher deflections than the target design deflections, indicating insufficient load bearing capacity. Two key factors for minimizing premature failures are: (1) prevention of water infiltration into the base through good surface mix, and (2) building a base that is moisture resistant. The strategy of using a crushed aggregate base as an interlayer has been utilized on other projects with success, provided it meets two key requirements: (1) Class 1 Texas Triaxial class, after 10 days capillarity and (2) the 10-day final dielectric should not exceed 13.