Static and cyclic behaviour of epoxy resin and bentonite-grouted sands

The purpose of the present study was to conduct a thorough laboratory investigation concerning the positive effect of pure amino-based epoxy resin grouts or epoxy resin grouts containing low amounts of bentonite on the strength of medium to fine sands under monotonic or dynamic loading. To assess the effect of grouting on the monotonic strength of grouted sands, a series of unconfined compression tests were performed on specimens at various curing ages and isotropically consolidated undrained triaxial tests on specimens at 90 days of curing. Isotropically consolidated undrained cyclic triaxial tests were also conducted to study the cyclic response of grouted sands. The laboratory test results demonstrated that the strength of the sands was remarkably improved by epoxy resin when combined with small dosages of bentonite under monotonic or cyclic loading. The mean increment in 90-day compressive strength, elastic modulus, friction angle and cohesion of grouted specimens is 130%, 88%, 51% and 74.8%, respectively, in relation to the ones without bentonite content. Also, grouted samples showed a large increase in cyclic resistance and failure occurred at significantly increased stress levels as well as at a higher number of loading cycles than for their un-grouted or pure epoxy resin grouted counterparts. Based on the experimental data from dynamic triaxial tests, we performed a non-linear regression analysis was performed to correlate the critical values of cyclic stress ratio to particular descriptor variables.