Immediate and Time-Dependent Compression of Tire Derived Aggregate

This paper examines immediate and time-dependent compression of tire derived aggregate (TDA) and TDA-soil composites. To accommodate large particle sizes, modified experimental devices were developed and used to test tire chips and tire shreds. Immediate compression of TDA, which results almost entirely from the reduction of pore volume, increases with TDA content and tire particle size. The secant constrained modulus (Msec) of TDA defined over the stress range of 0–50kPa varied from a low of 255kPa (100% tire shreds) to a high of 1,320kPa (50% tire chips). A characteristic relationship between strain and time exists for TDA and TDA composites under one-dimensional confined compression. Time-dependent deformation is well described by the modified secondary compression index (Cαε), which ranged from 0.0010 (50% tire chips) to 0.0074 (100% tire chips). Time-dependent deformation was inversely proportional to sand content, with the most significant changes resulting from the addition of 15% sand. Both applied stress and tire particle size appear to have a negligible effect on time-dependent compression of TDA. Based on the findings of this study it is recommended that practitioners assess time-dependent settlement when designing a TDA structure and if necessary incorporate design features to accommodate these settlements.