Application of recycled tire polymer fibers and glass fibers for clay reinforcement

Abstract

Soil reinforcement with fibers is a simple, efficient and low-cost (especially by incorporating waste or recycled fibers) technique for enhancing mechanical characteristics of soft soils. This experimental study investigates the effects of recycled tire polymer fibers (RTPF) and glass fibers (GF) on enhancing the strength/deformation properties of clays. A series of compaction, unconfined compression and direct shear tests were performed on precisely prepared composite soils comprising clay, with different amounts (i.e. 0.5, 1.0 and 1.5%) of RTPF and GF having varying lengths (5 and 10 mm). Laboratory findings indicated that the composite soils have lower dry density and higher optimum moisture content as compared to the clay. Both unconfined compression and shear strength test results on composite soils implied that while adding fibers increased the materials’ ductility, there was an optimal percentage of fibers (0.5% for RTPF and 1.0% for GF) causing the highest strength gain, beyond which strength decreased. Concerning the shear strength parameters, i.e. cohesion intercept and internal friction angle, the fiber inclusion was particularly influential in increasing cohesion, whereas changes in internal friction angle were minimal. Moreover, the shorter fibers (5 mm) were generally more efficient in reinforcing the clay. The fiber improved composite soils have a better ductility and load-bearing capacity compared to parent soils that can be beneficial in the construction of pavement and railway substructure, liners, small fills/dikes, backfills around pipes, and slope protections.