Clay Mineral Quantification Using Gravemetric Analysis

Abstract

The current procedure used by the Texas Department of Transportation (TxDOT) to determine the type of stabilizer is based mainly on the Plasticity Index (PI) and the gradation of the soil. This method of stabilization does not always work because two soils with the same PIs can have very different shrink/swell potential, plastic limits or liquid limits, hence their behavior may be very different. This is mainly due to the fact that two soils that have the same PI can have very different clay mineral composition. Montmorillonite and kaolinite are the clay minerals that cause swelling/shrinking in soils.Chittoori (2008) had developed three models to quantify the clay minerals using Microsoft Excel Solver, Regression Equations and Artificial Neural networks. The main objective of this research was to validate the recently developed models by Chittoori 2008 for quantifying montmorillonite and kaolinite. It was found that although all the models gave fair predictions, the regression equation accurately quantified high percentages of montmorillonite - the mineral that is the main cause of swelling and water retention in soils.