Characterisation of crushed base for mechanistic-empirical pavement design guide

This paper describes a recently completed laboratory test programme to determine the standard properties of crushed base aggregates collected from 14 road projects throughout Wyoming. Eleven of 14 base aggregates were selected for resilient modulus testing performed in accordance with the Wyoming modified AASHTO T 307 procedure. Effects of moisture content, percent fines content, stresses, and gradation on base resilient modulus were assessed. Models were developed using statistical methods to estimate the resilient modulus of base materials. The NCHRP and Hicks and Monismith constitutive models were calibrated. A design chart of resilient modulus in terms of asphalt thicknesses was established to facilitate the iterative process involved in a pavement design. Finally, a design table of base properties for MEPDG Level-3 inputs was developed to facilitate the full implementation of the MEPDG. The proposed framework for developing these methods could be adopted nationally to facilitate the full implementation of MEPDG.