Determination of static and dynamic behavior of recycled materials for highways

Utilization of wastes in highway applications may be feasible with a better understanding of waste behavior under static and dynamic loading. Waste materials such as tires, plastics, glass, fly ash, etc. may be used in highway construction potentially saving waste disposal costs. Physical, mechanical, and dynamic properties of waste materials are required for a successful design, which can be determined using techniques available in geotechnical engineering. Construction of highway fills in earthquake prone regions requires knowledge of dynamic behavior of the waste materials. Due to its low unit weight, high porosity, and interlocking behavior, waste materials response to earthquake loads are different from those of natural soil. In this study, large-scale direct shear tests and dynamic triaxial tests were carried out for two potential wastes: tire buffings and manufactured fly ash pellet aggregates. Tire buffings added to sand altered the deformation behavior of the mixture by stiffening the material at low strains and softening the mixture at large strains. The shear modulus and damping values of sand-tire buffings mixtures were higher than those measured for tire buffings only. Processing fly ash to manufacture pellet aggregates resulted in high performance fill material with an internal friction angle of 46degrees and with unit weight of 10.5 kN/m(3). The shear modulus values of pellet aggregates were slightly lower than those of tire buffings added sand, and the damping values were as high as those for tire buffings-sand mixture. (C) 2004 Elsevier B.V. All rights reserved.