Geomechanical and Hydraulic Behavior of Maryland Graded Aggregate Base Materials

Abstract

Maryland State Highway Administration (SHA) is in need for evaluation of stiffness and drainage characteristics of graded aggregate base (GAB) stone delivered at highly variable gradations to the construction sites. To fulfill the current need, the mechanical and drainage properties of several Maryland GAB materials were evaluated in the laboratory and field. The resilient modulus (RM) and hydraulic conductivity (HC) test results obtained in the laboratory were compared to the field RM and HC. The effect of moisture content on RM was also evaluated. Summary RM values at Optimum Moisture Content (OMC) minus 2% were higher than those at OMC, with few exceptions; however, the permanent deformations were increased with addition of moisture content. An addition of 4-6% fines over the SHA specification limit of 8% resulted in 2-5 times decrease in the laboratory-based GAB's HC and an increase in time for 50% completion of the drainage.