Characterization of dispersive soil by a new approach

Abstract

Dispersive soils occur in many parts of the world such as United States, Australia, Greece, Latin America, South Africa, and Thailand and even some areas in India. These soils are easily erodible and segregate in water by the process of deflocculation. This causes serious problems for the stability of earth and earth retaining structures. Soil dispersivity is mainly due to the presence of xchangeable sodium present in the soil. The erosion due to the dispersion of soil depends on mineralogy and clay chemistry and the dissolved salts in pore water. The mechanism of dispersivity of soils is reasonably well understood that when attractive forces are less, repulsive forces make the particle to segregate and to move in suspension. Even though in current practice simple methods are available to identify the dispersibility of soil, the quantification of dispersibility is hard. Visual classification, Atterberg limits and particle size analysis do not provide sufficient basis to differentiate between dispersive clays and ordinary erosion resistant clays. Pinhole test, Emersion Crumb Test, Chemical test and double hydrometer test are the tests that are in vogue to identify the dispersive soils. This research explores the possibility of using other standard tests such as shrinkage limit, liquid limit, plastic limit, shear strength, conductivity, turbidity and pH to quantify the dispersivity of the soils by collecting samples from different places of Tamilnadu. The Index and Engineering properties and Dispersion of the soils were found and the correlation between the dispersivity and other properties are developed to identify the dispersive soil easily. The part of the research activity also focuses on designing new equipment reliable for determining the rate and quantity of dispersion of the soil. This apparatus will simplify the procedure for finding the percentage of dispersion, quantity of dispersion of the soil and also the rate of dispersion newline