This paper investigates the rubber inclusion effect on the strength and physical characteristics of composite geomaterial (CGM) in which dredged soil, crumb rubber and bottom ash are reused for recycling. Several series of test specimens were prepared at 5 different percentages of rubber content (i.e. 0%, 25%, 50%, 75%, and 100% by weight of the dry dredged soil) and three different percentages of bottom ash content (i.e. 0%, 50% and 100% by weight of the dry dredged soil). The mixed soil specimens were subjected to unconfined compression and elastic wave tests to investigate their unconfined compressive strengths and small strain properties. The test results indicated that the rubber content and bottom ash content were found to influence the strength and stress-strain behavior of CGM. Overall, the bulk unit weight, the unconfined compressive strength, elastic wave velocity, and small strain moduli of CGM were found to decrease with increasing rubber content. The results of elastic wave tests indicate that the higher rubber content, the lower elastic wave velocity and the lower shear modulus. Among the samples tested in this study, those with a lower rubber content exhibited sand-like behavior and a higher shear modulus.
Due to the large number of vehicles being manufactured, discarded tires have become an ongoing environmental problem worldwide. In Korea, approximately 20 million tires are discarded annually as shown in Fig. 1. More than 500 million tires are discarded in the United States every year. Some of these tires are left stockpiled in landfills or are illegally dumped, providing breeding grounds for harmful insects and rodents (Rubber Manufacturers Association, 2006). Discarded tires can be classified into several groups, based on shape and size: whole tire, slit tire, shredded or chipped tire, ground rubber, or crumb rubber.
