Evaluating the Influence of Additives on Swelling Characteristics of Expansive Soils

Abstract

Stabilization is one of the most preferred techniques of dealing with expansive soils. Several types of additives have been evolved and are successfully being used for this purpose. This paper evaluates the performance of a variety of additives categorized into (a) cementitious: lime and fly ash (b) non-cementitious: stone dust, and (c) chemical additives: CaCl2 and Na2SiO3, when employed to stabilize three types of expansive soils used in the study. Attempts were also made to investigate the influence of valence of cations (viz., monovalent, divalent and trivalent) and mean particle diameter (d50) of additive(s) on percentage reduction of swelling characteristics. Results reveal that each additive exhibits distinct response on the swelling behavior of expansive soils. It has been observed that chemical additives exhibit superior performance over cementitious and non-cementitious additives in reducing the swelling characteristics. Further, it has also been found that valence has profound influence on the swelling characteristics of expansive soils. As such, the degree of reduction of swelling was found significantly high when employed chemical additive consists of trivalent cations than its counterpart additive consists of mono- or divalent cations. Further, efforts were also devoted to correlate mean particle diameter of additives with swelling characteristics, and it was clearly evident from trends that an appreciable decrease in swelling characteristics occurs with decrease in mean particle diameter.