The role of clay minerals in marly soils on its stability

In many sub-tropical and tropical regions of the world, lime or cement stabilization of marry soils is used as a convenient and expedient mesas for the development of foundation base courses and inexpensive wearing courses for transport purposes. The failure of many of these natural and stabilized marry soils to perform their functions have been reported. Mechanical factors generally used to explain the causes for the foundation failures have not been satisfactorily accepted. This study uses thermodynamic modelling and X-ray diffraction analysis to explain the general basic causes for deterioration of the support capability of these types of soils. The presence of palygorskite in marry soils provides it with some very unique features in its natural state, and particularly when it is stabilized with lime or cement. Formation of an expansive mineral, ettringite, as a transformation product of palygorskite increases the swelling potential of the stabilized soils. The various interactions, reactions and factors contributing to the stability and instability of marry soils, and lime stabilized marry soils are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.