Compressibility and Shear Strength Properties of Tire-Derived Aggregate Mixed with Lightweight Aggregate

Abstract

Lightweight materials such as expanded shale/clay/slate or tufts and slag are used in the construction of rigid culverts to mitigate high earth loads and settlements. However, the cost of using lightweight aggregate can be high compared with using normal-weight backfill. In the design and construction of induced trench culverts, lightweight waste materials such as sawdust, wood chips, and tire-derived aggregates (TDAs) have been successfully used. One of the concerns with the use of sawdust and wood chips is their high compressibility and possible degradation over long design life. In the case of thick zones of tire-derived aggregates, generation of heat and fire hazard are regarded as disadvantages. To address the concerns pertaining to the high cost of lightweight aggregate and the use of thick zones of TDA, the use of lightweight aggregate mixed with TDA is presented in this paper. A laboratory testing program determines the geotechnical properties of expanded shale lightweight aggregate, tire-derived aggregate, and their mixtures using a large direct shear box, one-dimensional compression testing equipment, and a split-ring apparatus. Various mixtures are evaluated for shear strength, compressibility, and coefficient of earth pressure at rest.