Aging Effects on Swell Potential of Compacted Clay

The swelling potential of compacted clay, which develops upon inundation, is first defined in terms of the parameters affected by aging. These parameters include swell pressure, volume change and suction. Because in nature the clay is exposed to water some time after compaction, the aging effects on the swelling potential are rather important. Compacted clay samples were aged for up to 90 days and then tested for swelling pressure and free swell, using triaxial technique. It was found that the swell pressure, particularly at high initial densities, tends to increase with aging and then gradually to decrease to the initial value of zero aging. The amount of swell (under practically zero load) was not markedly affected by aging. The peak values of the swelling potential amounted to two to three times the initial value, and they were found to be dependent on the initial placement conditions of the clay. The results are explained by energy concepts, as well as by concepts mainly used in soil science, such as thixotropy and entropy of clay-water systems.