Mechanical properties of bentonite soil stabilized with rice husk ash and ground granulated blast furnace slag geopolymer

This paper exhibits a method of stabilizing bentonite soil, a kind of extraordinarily expansive soil, using rice husk ash (RHA) and ground granulated blast furnace slag (GGBS) geopolymer to determine its potential use in pavements. The precursors RHA and GGBS are activated by alkaline reagents sodium silicate and sodium hydroxide. Geotechnical parameters, viz. Atterberg limits, optimum moisture content, maximum dry density, unconfined compressive strength, and morphological analysis are studied. The combination of precursors and alkaline reagents reduces the plasticity index of bentonite significantly from 258.2 to 61.22%. The unconfined compressive strength of geopolymer-treated bentonite reaches 6.02 MPa after 28 days. Scanning electron microscopy reveals the geopolymerization mechanism. A denser structure is formed which is associated not only with the physical interactions but with chemical compounds as N-A-S-H and C-A-S-H created by the free species of Si-, Al-, and Ca- which are confirmed to be leached from RHA and GGBS. The regression analysis shows that the plasticity index, optimum moisture content, maximum dry density, and unconfined compressive strength of geopolymer-treated bentonite are highly correlated to the precursor replacement.