A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering of the Asian Institute of Technology, Bangkok, Thailand

Thesis (M.Eng.) - Asian Institute of Technology, 1969

Lateritic soils from 11 different sources in Thailand were studied to investigate the effect of methods of preparation of samples on their index properties. These effects were correlated with the chemical properties and mineralogical composition of the soils. The difficulties encountered in the classification of these soils using the present classification systems were discussed. Results showed that air or oven drying reduced the liquid and plastic limit values. Greater changes in limits were observed in soils containing montmorillonite as one of the clay minerals. Clay contents (less than 0.002 mm) in most cases reduced due to oven drying but the changes were not very significant. The peculiar behavior of reduction in limits and clay content suggested that the clay particles coated with iron oxide were coagulated upon oven drying to form clusters of particles. Decrease in the specific surface resulted in reduction of limits and clay content values. The use of present classification systems might give very misleading ideas about the behavior of lateritic soil.