Rational Approach for Base Type Selection

Abstract

The objective of this study was to investigate how base materials should be properly selected for specific types of pavement, considering not only the performance of individual layers but also how they interact in the completed pavement structure. Base types considered included: granular (GB), lean concrete (LCB), asphalt treated (ATB), cement treated (CTB), and permeable asphalt treated (PATB) bases, constructed under both hot mix asphalt (HMA) and Portland cement concrete (PCC) pavements. The Long Term Pavement Performance (LTPP) Seasonal Monitoring Program (SMP) sites investigated included four SMP sections in the North Carolina SPS-2 experiment on US52 (wet-no-freeze zone) and 13 SMP sections in the SPS-1 and SPS-2 experiments on the Ohio SHRP Test Road (wet-freeze zone). The NC site contained two GB and two LCB sections, and the OH site contained eight GB, one ATB, two PATB, and two LCB sections. Environmental data were collected via seasonal monitors and time domain reflectometry. Pavement performance was monitored by obtaining periodic condition surveys and falling weight deflectometer measurements. Major findings of the study included the fact that base type had little impact on subgrade moisture and that the choice of base depends chiefly on three requirements: (1) appropriate stiffness; (2) sufficient permeability; and (3) good constructability. Guidelines for the selection of bases under flexible and rigid pavements are given.