Experimental Study on Normalized Stress-Strain Behavior of Geogrid Reinforced Rubber Sand Mixtures

Abstract

Rubber-sand mixtures (RSMs) have long been recognized as light filling back material and energy absorbing material with wide usage in civil engineering. As addition of rubber particles into sands usually decreases the strength of base sand, it is necessary to reinforce RSMs to satisfy the need of practical engineering. This paper presents studies on the behavior of geogrid reinforced RSMs. Conventional triaxial shear tests were carried out on reinforced/un-reinforced RSMs. Four kinds of geogrid reinforcing patterns, i.e., horizontal reinforcing with one layer, two layers, three layers, and vertical reinforcing were taken into accounted, and three kinds of confining pressures, i.e., 50 kPa, 100 kPa and 200 kPa were applied. Experimental results indicate that: (1) Comparing to un-reinforced RSMs, the stress-strain curves of RSMs reinforced by geogrid are enhanced in turn for vertical reinforcing, horizontal one layer reinforcing, horizontal two layer reinforcing, horizontal three layer reinforcing respectively. (2) The stress-strain relationship of RSMs reinforced by geogrid exhibits strain hardening characteristics instead of strain softening before reinforced. (3) The reinforcement effect coefficient on the failure stress of RSM is higher than that of pure sand, and at the low confining pressure, this phenomenon is more obvious. (4) Geogrid reinforcement can restore the strength of the RSMs with less effect on the modulus. That is, reinforced RSMs can maintain the merits of low modulus and high strength simultaneously. (5) The stress-strain relationship of the reinforced RSM could be well normalized with the failure stress adopted as the normalized factor, based on the established normalization equation, the stress - strain curves could be predicted well.