Abstract
Dispersive soils which occur in many parts of the world are easily erodible and segregate in water pose serious problems of stability of earth and earth retaining structures. The mechanism of dispersivity of soils is reasonably well understood. However there is simple method to identify the dispersivity of the soils and even more difficult to quantify the dispersivity. Visual classification, Atterberg’s limits and particle size analysis do not provide sufficient basis to differentiate between dispersive clays and ordinary erosion resistant clays. Pinhole test and double hydrometer test are the only two tests that are in vogue to identify the dispersive soils. This paper explores the possibility of using other standard tests such as shrinkage limit and unconfined compressive strength tests to quantify the dispersivity of the soils. The rationale of using the methods and correlation between the dispersivity determined by various methods has been explained. It has been concluded that dispersivity ascertained from strength tests is more reliable.
Highlights
The soils that are highly susceptible to erosion and containing high percentage of exchangeable sodium ions are called Dispersive soils
This paper explores the possibility of using other standard tests such as shrinkage limit and unconfined compressive strength tests to quantify the dispersivity of the soils
Dispersivity is obtained from pin hole test, double hydrometer test, crumb test etc
Summary
The soils that are highly susceptible to erosion and containing high percentage of exchangeable sodium ions are called Dispersive soils. These soils are found extensively in United States, Australia, Greece, India, Latin America, South Africa and Thailand. These soils are erodible in nature and have tendency to segregate in presence of water and erode under small seepage velocity leading to problems of stability of earth and earth retaining structures. Water moving through the cracks picks up dispersive clay particles, with the rate of removal increasing as the seepage velocity increases [5]
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