Impact of Rice Husk Ash Based-Geopolymer on Some Geotechnical Properties of Selected Residual Tropical Soils

There is usually a need to enhance the properties of soils with poor geotechnical properties encountered during construction. The  utilisation of Rice Husk Ash (RHA) - based geopolymer for improving some properties of two selected tropical soils was investigated. The  Atterberg’s limits (Liquid limit, LL and plastic limit, PL), compaction properties (maximum dry density, MDD and optimum moisture  content, OMC), California bearing ratio (CBR) and unconfined compression strength (UCS) of the un-stabilized and stabilized soils were  estimated. The soil samples were stabilized with alkali activated RHA varying from 3 to 15% (in 3% increment). Alkaline activation was  achieved by using a mixture of NaOH(aq) and Na2SiO3(aq) in ratio 1:2. Mineralogy and elemental analysis of the un-stabilized soils, RHA  and stabilized soils were obtained using X-Ray diffraction, X-Ray Fluorescence, EDS and SEM. The LL and PI of the stabilized soils  decreased with as much as 30 and 40%, respectively, while the CBR and UCS increased as much as 300% and 1500%, respectively. SEM and  EDS analysis of the treated soil showed the formation of crystalline hydration products. It is concluded that RHA based geopolymer  is a potential environmentally sustainable stabiliser in tropical climatic condition.