Moisture and Dry Density Influence on Compacted Clay and Clay-Sand Mixtures

The influence of initial moisture content and dry density on swelling clays was extensively investigated in the literature. In order to explore the relationships that exist between the swelling parameters of clay soils and the water content, initial dry density, and sand content, a series of experimental tests were conducted on pure clay and clay treated with 20% sand. The swelling pressure and the swell potential were also tested for sand-clay mixtures. The results showed a significant influence of the initial water content on the swell potential of bentonite and bentonite sand mixture. The increase in the dry density was found to boost the swelling pressure and swell potential. The rate of increase is related to sand content. For higher sand content, it was found that grain-to-grain contact reduces the compressibility of the mixture and thus causes the general swell trend to alter. The amount of clay particles within the mixture is an important factor affecting the swelling. The results demonstrated the effectiveness of the sand in the reduction of swelling parameters. This study provides a control measure for expansive soil materials using sand addition to achieve better soil for construction purposes.