Mechanical Behavior of Pre-Test-Curing Nanoclay-Treated Gypseous Sand

Abstract

This work investigates the effect of pre-test curing at various durations on the stress-settlement of gypseous sand soil treated with varying percentages of nanoclay. The tests are performed on a soil sample from Al-Jameh district in northern Al-Najaf city, Iraq. The soil sample is disturbed and remolded in the Oedometer cell. The remolded specimen will be at 90% of the maximum dry density from the standard Proctor test. Four data sets related to the percentages of adding nanoclay, 0, 3, 6 and 12 %. Each data set includes three groups of pre-test curing periods (Tc), 0, 1 and 4 days. For each tested specimen, a gradual incremental normal stress is applied, i.e., 50, 100 and 200 kPa. For the soil without nanoclay, it was an interesting result for the performance under all vertical stresses that there is a slight decrease in the final settlement. This situation may be attributed to the re-bonded of the particles by the gypsum during the curing time. There was a clear decrease in the final settlement for the nanoclay-treated soil specimens compared to the natural state of the soil (without nanoclay). While a significant decrease in settlement is recorded for specimens with nanoclay (NC) of 6%, which is the best percentage of nanoclay.