Effect of Soil Gradation on Shear Strength of Soil

Abstract

Some factors have a significant impact on the shearing strength of soils. These factors that could affect the shear strength of granular material including the mineral composition of the soil, the initial moisture content, the degree of saturation, the over-consolidation ratio, the initial void ratio, and the porosity. The aim of the research was to evaluate the effect of gradation on the shear strength of the fine soils mixed with different ratios of sand contents. Three mixture models of different type of soil were suggested which are 100% kaolinite, 80% kaolinite with 20% sand, and 60% kaolinite with 40% sand, and stimulated by the Unconfined Compressive Strength (UCS) test to study the different gradation on the shear strength of the mixing an amount of sand with kaolinite as the base soil. The evaluation of data obtained indicated that soil gradation has a significant influence on shear strength parameters, the sample with 80% kaolinite plus 20% sand has the highest shear strength at a moisture content of 17%. Optimum percentage of sand as frictional angle contributor in soil mixtures needed to be determined in manufacturing high strength soil-based construction material.