Tire derived aggregate (TDA) is composed of shreds of scrap tires varying in size. Tire
derived aggregate has been used as a replacement for crushed rock aggregate in various
Civil Engineering applications including embankments, pavement structures, fill, and
leachate collection systems. Using shredded tire in lieu of conventional rock aggregates
offers environmental and economic benefits. Tire derived aggregate has good thermal
insulator characteristics and can therefore be used to reduce frost penetration. It also
promotes good drainage, is lightweight, compressible, and has no harmful leachates.
Using tire derived aggregate offers these unique properties at a reduced cost compared to
conventional aggregates. Using tire derived aggregate also reduces pressures on aggregate
pits and landfills, where the tires would otherwise be discarded.
This study examined the physical characteristics of tire derived aggregate and sand mixes in
the laboratory for road sub-structure drainage applications. Non-linear permeability and
stiffness analysis of 100% TDA, 100% sand, and various TDA-sand blends was performed. It
was found that a 70/30 blend of clean sand and tire derived aggregate provides adequate
structural capacity while still maintaining good drainage characteristics. The material
properties of these mixes were used as inputs in a three dimensional finite element model
to perform simulations and generate road primary response outputs. Based on the analysis
performed, it was determined that tire derived aggregate systems exhibit highly non-linear
material constitutive behaviour in terms of permeability as well as mechanical primary
response with respect to stress state. It was also determined that when designed properly,
tire derived aggregate is a technically and economically sound alternative for road
substructure drainage layers.
