Mechanisms of clay stabilization with inorganic acids and alkalis

Abstract

A series of mono- and di-valent cation hydroxides, and certain strong acids, were allowed to react with a two- and a three-layer clay mineral (kaolin and montmorillonite) under conditions simulating those for normal soil stabilization in field practice, i.e. mixed, remoulded, and moist-cured at a moisture content and density approximating optimum compaction conditions. The progress of reaction was followed over extended periods of time, up to two years. Changes in strength and volume were correlated with chemical and mineralogical changes in order to identify those bonding mechanisms which contribute to inorganic soil stabilization. For an additive level of 10% by weight dry clay basis (9.1% total dry solids basis) it was shown that several distinct stabilization mechanisms exist. One major mechanism is the surface coating of fabric units, and another the reinforcement of the soil by product formation in crevices, angularities, pore constrictions, and similar defects which influence the mechanical properties of the whole sample. The importance of these reactions to practical soil stabilization is thus demonstrated.