Potentials of Cement Kiln Dust and Rice Husk Ash Blend on Strength of Tropical Soil for Sustainable Road Construction Material

The growing problem of containing wastes in developing countries has led to endless research on the chances of converting these wastes to materials for sustainable engineering construction. This study through experimental assessment explores the potentials of cement kiln dust (CKD) and rice husk ash (RHA), in circumventing the inadequacies often encountered in deficient tropical soil thereby ensuring profitable engineering construction. Specimens were prepared by blending dosages of 0, 2, 4, 6 and 8 % CKD as well as 0, 3, 6, 9, 12 and 15 % RHA by requisite weight of soil. The investigated outcomes revealed increasing cation exchange capacity (CEC) with corresponding increase in pH for the various increased CKD-RHA composition. The Atterberg limits indicated a reduction trend with increasing CKD-RHA blend, signifying a drastic improvement in the plasticity tendency of the soil. While the maximum dry density (MDD) decreased with up shoot in optimum moisture content (OMC) at varying combined dosages of CKD and RHA, the CBR (soaked condition) increased steadily from 5 % (natural) to peak of 35 % at 8 % CKD / 15 % RHA blend. The highest CBR value in this study was not below the criterion of 20 – 30 % for sub-base as well as 10 – 15 % for subgrade road material. The regression analysis and analysis of variance from laboratory results validated the experimental outcome of using CKD-RHA blend to expressively enhance deficient lateritic soil. The outcome of this study has shown that CKD-RHA is recommended in improvement of strength of weak soil for either sub-base or more fittingly, subgrade of flexible pavement. Hence, using these waste materials will solve the twofold objective of proper waste management and good engineering materials for sustainability in construction of subgrade of flexible pavement.