Evaluation of strength parameters of stress-strain development in clay soil and clay-sand soil

Soil strength and elasticity modules are important parameters in the soil engineering. Elasticity module shows the potential of soil deformation. In this research, samples of problematic clay soil and stabilized clay soil with sand, were provided and investigated. The samples were built in various moistures and different compactions, and then those in unconfined set were tested. The moisture in these experiments are, optimum wet content, 2% less than of this, 4% less, 2% more than of this and 4% more. The applied compactions, R.C, are equal to 85, 95 and 100 percent. Using data gathered, the soil axial strengths and elasticity modules were calculated. Findings show that for entire samples in clay and sand-clay, increase of moisture leads to decrease of the soil axial strength. Nevertheless, the decreasing intensity of soil strength in sand-clay is more than the problematic clay soils. Results of the experiments show that the change of wet content from 4% less than optimum moisture to 4% more, decreases soil axial strength of problematic clay soil, to approximately 84%, while, this amount for sand-clay soil is about 93 percent. Moreover, the decrease of elasticity module in sand-clay samples with 100% compaction and 13% wet content is approximately 51 percent.