Small-strain stiffness degradation of artificially cemented sands

This paper investigates the degradation of small-strain stiffness of artificially cemented sand subjected to isotropic loading cycles using bender elements. Samples with cement contents of 3 and 5% were allowed to cure for 72 h using fast-setting Portland cement under a constant confining pressure of 200 kPa. Two types of tests were conducted on the samples: 'load-unload' test, where samples were subjected to increasing isotropic confining pressures and then returning to the initial pressure of 200 kPa; and 'unload-load' test, where samples were subjected to decreasing confining pressures and then taken back to the initial pressure of 200 kPa. The effect of cementation on the initial microstructure of the samples was analysed using X-ray computed tomography and scanning electron microscope. Cemented samples showed a clear degradation of the normalised small-strain stiffness, after a differential confining pressure was applied, suggesting that the cemented matrix is highly affected by isotropic loading cycles.