Evaluation of Effect of Bentonite Addition on Fine-grain,s Behaviour Properties

One way of reduction of leakage from beneath of earth dams is using of one contact clay layer with very low permeability and intermediate to high plastisity and connectig it to core of dam. Since، most of fine-grained soil in environtment of dam have low plastisity and preparing it from another place is not economic، use of bentonite in order to improvement of engineering characteristic of borrowed clay is suitable way. In this search effect of bentonite on geotechnical properties of fine-grained soils with low plastisity are evaluated. Results of this research show that hydraulic conductivity، consolidation coefficient، dry density، colifornia bearing ratio (CBR)، …are decreased with increase in bentonite content but optimum moisture، Aterberg limits، cohession and so on are increased with bentonite addition. Finally، with analysis of obtained result، optimum percent of bentonite is offered in order to improve of engineering properties of used clay in contact region.