Studying collapse potential of gypseous soil treated by grouting

Gypseous soil is a collapsible soil, which causes large deformations in the buildings which are constructed on it. Therefore, several methods have been used to minimize this effect, such as replacing the gypseous soil or stabilizing it (grouting or soil improvement).This study presents the results of tests carried out on four types of gypseous soil with different properties and various gypsum contents. The testing was conducted on undisturbed samples to evaluate the compressibility of the gypseous soil under different conditions. The samples were grouted with acrylate liquid. The treated samples showed that the acrylate liquid was able to reduce the compressibility of the gypseous soil by more than 60–70%. This is attributed to the acrylate liquid film coating the gypsum particles, and thus, isolating them from being subjected to the effect of water. The treated gypseous samples exhibited a low collapse potential in which the acrylate liquid reduced the collapsibility of the gypseous soil by more than 50–60%. The acrylate liquid affected the shear strength parameters of the gypseous soil by increasing the cohesion and decreasing the angle of internal friction.For unsoaked samples, it was observed that the cohesion increased and the angle of internal friction relatively decreased. This behaviour may be attributed to the cohesion effect, caused by the presence of the acrylate liquid, and because contact between particles was prevented which caused a reduction in friction. As long as the specimens were saturated, the strength of the sand appeared to increase at the same rate as for an increase in total stress. Once the sand became unsaturated, the rate of increase in strength decreased, and in fact, the strength decreased when the suction was increased beyond some limiting value.