Evaluation of the effect of sand grain size on compressive strength and elasticity module of lime-treated soil

Using additives can improve the mechanical properties of soils of construction projects such as irrigation canals. The materials such as sand, in addition to improving soil conditions, are compatible with the environment. So, in recent decades, the utilization of sandy soils in the construct of irrigation networks has been extended. In this study, the effect of size and amount of sand on the strength characteristics of lime treated soils. In this way, at first, to determine the best soil-lime mixture, the soil was mixed by different amount of lime and unconfined compressive strength of these has been investigated. The highest unconfined compressive strength was achieved by adding 7 percent lime to the soil. Then, a set of tests conducted on coarse (D50= 1.4 mm), medium (D50= 0.45 mm) and fine (D50= 0.22 mm) and by applying 5, 10 and 15 percent of sand to lime-clay mixture in three replicates. The unconfined compressive strength was performed on the specimen at curing time of 7, 14 and 28 days. Results showed that adding 5 percent of coarse sand to clay–lime mixture can increase compressive strength and elasticity module about 13 percent and 16 percent, respectively, on average. In addition, adding medium and fine sands can cause to deteriorate soil’s strength and elasticity module.