A rapid method of determination of swell potential and swell pressure of expansive soils using constant rate of strain apparatus

Swell potential and pressure of expansive soils are conventionally determined using an oedometer apparatus. The specimens are commonly saturated by submerging in water under a seating pressure. Generally, the test takes a long time, as the saturation process is slow. This article presents an improved saturation method by back pressure application in a constant rate of strain (CRS) loading apparatus. Controlled strain loading (CSL) was adopted to bring back the swollen specimens to their initial thickness instead of conventional incremental loading. It is observed that the time taken to complete the test is 7 to 13 times faster compared to the conventional method. When compared to the conventional method, the swell potential and pressure values obtained with the back pressure saturation were found to be higher by about 19 % to 34 % and 6 % to 28 %, respectively. The reason for these higher values is attributed to the attainment of greater saturation using the back pressure saturation technique.