Effect of gradation and source properties on stability and drainability of aggregate bases: a laboratory and field study

Abstract

A combined laboratory and field study was undertaken to evaluate the effect of gradation on resilient modulus (M R) and falling weight deflectometre (FWD) modulus (M FWD) as measures of stability and coefficient of permeability (k) as an indicator of drainability of aggregate bases. Aggregates from three different sources in Oklahoma and three gradations consisting of M-AASHTO #57, ODOT Type A and OKAA Type M were used. M R and k tests on compacted aggregate specimens were conducted in the laboratory. Also, a 152.4-m long test section was constructed with the aforementioned gradations and FWD and in-situ falling head permeability tests were conducted periodically. Results showed that denser gradations resulted in higher M R and M FWD and lower k values, both in the laboratory and in the field. M FWD and field k values were found to increase and decrease, respectively, with time, possibly due to traffic-induced compaction. Regression models were developed to estimate M R and k in terms of gradation and source properties of aggregates.