Effect of Particle Shape on Durability and Performance of Unbound Aggregate Base

Abstract

AbstractEffects of particle shape on the durability (as determined from micro-Deval test) and performance [as determined from resilient modulus (MR), and permanent deformation (PD) tests] of unbound aggregate base (UAB) used in road structures have been evaluated in detail. Four crushed aggregates with different mineralogy (but similar angularity) were selected, and each aggregate type was mixed based on varying particle shapes (ranging from flat to equidimensional) to create dense- and open-graded gradations. The findings showed that the increase in flatness ratio affects the compaction and interlocking characteristics of the open-graded UAB materials much more than the dense-graded UAB materials. For open-graded UAB samples, the MR of the aggregates, regardless of the mineralogy, increased with increasing flatness ratio. The MR values of the dense-graded aggregates had an observed peak value at a flatness ratio of 0.6, whereas the final permanent strain during PD testing increased with increasing flatne...