Evaluation of Hydraulic and Strength Characteristics of Sand-Bentonite Mixtures with Added Tire Fiber for Landfill Application

Abstract

Compacted sand-bentonite mixtures have been treated as a good substitute for the barrier material at the landfill. At low stress, desiccation-induced moisture variations may cause a reduction in the plastic deformability of bentonite and shrinkage cracking, which can increase the uncontrolled migration of leachates. In addition, if the strength of the base material is not good enough, then the effective operation of the liner system may be threatened. Waste tire fiber continues to be a major environmental concern for all around the world; hence, it is quite essential to reuse waste tire fiber in order to reduce environmental and health hazard problems. Consistent with this fact, the potential benefit of using the waste tire fiber for landfill application has arisen to enhance the material function. Therefore, the objective of this study was to examine the possibility of adding tire fiber as a reinforcement material to sand-bentonite mixtures to improve the stability of the liner without significantly increasing its hydraulic conductivity. Tests were performed on sand and bentonite mixtures mixed in a proportion of 90∶10 and 80∶10 and with 5%, 10%, and 15% of tire fiber. Test results suggested that the inclusion of 15% tire fiber made a sand-bentonite mixture less prone to swelling. The compression index and swelling indexes are affected by the presence of the tire fiber in the mixture. With the inclusion of the tire fiber, a greater increase in hydraulic conductivity was observed for the mixture containing a higher amount of bentonite. The addition of tire fiber enhanced the effective strength parameter of the mixture. The energy absorption capacity (EAC) of the mixture sharply increased with tire fiber content and confining pressure; however, it decreased with an increase in the bentonite content in the mixture.