Experimental Study on Cement Kiln Dust Based Geopolymer as Subgrade Soil Stabilizer

Abstract

Expansive soil drastically changes phase from being too hard in the summer to becoming slushy in the monsoon season, due to its swell – shrink behavior, that is why engineering properties of the expansive soil must be enhanced before constructing the road infrastructure on such soils. The present research work shows the results of experimental work carried out to enhance the engineering properties of Black Cotton Soil (BCS) by utilizing cement kiln dust (CKD) and cement kiln dust based geopolymer. The efficiency of this binder is discussed in terms of maximum dry density (MDD), optimum moisture content (OMC) and California bearing ratio (CBR) of stabilized soil. In geopolymer synthesis, combination of sodium silicate (SS – Na2SiO3) and sodium hydroxide (SH – NaOH) is used as a soluble alkali activator. The discussion of result of alkali activation is done in the form of stabilization of black cotton soil with cement kiln dust. Six different CKD percentages with respect to the total solids (soil + CKD) weight, is used: 5%, 10%, 15%, 20%, 25% and 30%. The three different percentages of cement kiln dust (10%, 20% and 30%) are activated with blend of sodium silicate and 4, 7, 10 and 13 molar concentrations of sodium hydroxide solutions. The ratio of sodium silicate to sodium hydroxide solution by dry mass is kept constant as 2:1. The most effective concentration of alkali activator and dust/soil ratio is determined.