Evaluation of Drainable Base Materials under Asphalt Pavement

Providing free-draining materials as a base layer under the asphalt pavement has been adopted by many state highway agencies to prevent premature water-related pavement failure. The drainable base materials should possess not only high permeability but also high strength and stiffness to sustain traffic loads. In Ohio, there are four unbound aggregate base materials specifications and two types of bound base materials. This paper presents laboratory test results of mechanical properties of such drainable base materials, including resilient modulus, strength and permanent deformation under cyclic loads, durability, and permeability. Furthermore, field moisture monitoring data of fully instrumented pavement sections built up with different drainable base materials will be presented. It is shown that based on laboratory and field monitoring data obtained, the ODOT 306 cement treated base performed as the best drainable base material.