Influencing factors for uniaxial tensile strength of dispersive soils

In order to measure the tensile strength accurately, by using the self-developed moulds and the electric uniaxial tensile tester and comparing the transitional soils with the non-dispersive ones, the influencing factors for tensile strength and fracture mechanism of dispersive soils are studied. The experimental results show that the tester can effectively avoid the end effect and the influence of weight if the length-diameter aspect ratio is 2.5 and the tensile rate is 0.8 mm/min. The uniaxial tensile strengths of the three kinds of soil samples all decrease with the increase of the moisture content and increase with the increase of compactness and clay content. The uniaxial tensile strength of the dispersive soils is lower than that of the transitional soils and non-dispersive soils. The main reasons are that the dispersive soils have a certain amount of Na⁺ and alkaline pH. These factors make the diffusion double layers thicker and lead to smaller gravitational and larger repulsion among particles. Thus the tensile strength becomes lower macroscopically.