DefinePK

Abstract

Construction of building structures on very weak or soft soil is considered as unstable and unsafe. Improvement of the soil strength may be tackled by different subgrade improvement methods or techniques; bentonite has been selected as the binding material which was randomly included into the soil at five different percentages of bentonite content, i.e. 3 %, 6 %, 9 %, 12% and 15% by weight of soil. The main task of this work is the improvement of cohesionless soil engineering properties by using bentonite. The selected improved soil properties are shear strength and maximum dry density which are effect the bearing capacity of structure foundations and their stability. After improvement, cohesionless has gain some apparent cohesion by rearrangement of soil particles and decrease the voids between the particles by adding fine particles between them and decrease voids and increase the density, then the required properties can be improved. The soil grain size distribution and the unified soil classification system are used to distinguish the soil sample. The soil is classified or named as (sandy poorly graded) in this work. The experimental program consists of standard Proctor tests, and direct shear tests which were conducted on the cohesionless soil-bentonite mixtures to study their properties. Based on the result obtained, the short coming of this treatment is the increasing in maximum dry density and shear strength with acceptable amount. It is found that the 9 % of bentonite content is the optimum value which gives the better results obtained in this study.