experimental study of volume change and swelling pressure of compacting of clay soil

expansive behavior is usually observed in soils, which contain fractions of clay minerals in their composition. water absorption of clay particles and change of natural water content of soil up to plastic limit and down to shrinkage limit will cause significant volume change in expansive soils and will result in severe damages to the structures, buildings and foundations. swelling potential is directly related to clay minerals activity and soil plasticity. besides all the parameters expressing composition of a soil environmental conditions provide conditions to free the swelling potential. in the present study, in order to observe effects of soil mineralogy, plasticity and compaction indices such as water content and dry unit weight swelling behavior of five clay soils with plasticity index of 10 to 60 has been investigated. free swelling and constsnt volume swelling pressure tests have been done on compacted samples. results of experiments indicate the swelling potential increases by increasing plasticity index, and clay size fraction in soil composition.