Potential Use of Recycled Rubberized CLSM as Bridge Approach Backfill

摘要

Scrap tire disposal is a major environmental challenge around the world. This paper proposes a novel alternative using recycled crumb rubber as a controlled low strength material (CLSM) for bridge approach backfill. Laboratory tests performed to assess the engineering properties of CLSM consisted of recycled rubber fines and various ratios of native sand. Test results revealed that CLSM with rubber fines alone was not flowable and reasonable strength was not achievable with acceptable cost. The inclusion of 40% sand in a rubberized CLSM caused flowability and strength to increase markedly. The improvement can be attributed to increased water demand, the development of a stronger hydrated cement paste transition zone, and a denser particle packing within the sand-rubber mixture. The research indicated that rubberized CLSM containing 40% sand showed acceptable engineering properties for bridge approach backfill. The beneficial reuse of crumb rubbers as CLSM can be a practical alternative to reduce the accumulation of waste tires.