The study evaluated the effect of nanosilica extracted from rice husk ash using the acid wash method on some geotechnical propertities of lateritic soil treated with 0, 0.5, 1, 1.5 and 2 % by weight of nano silica content and compacted using the West African standard compactive effort. Samples were subjected to index, compaction, unconfined compressive strength and permeability tests. Tests results the showed that addition of nanosilica to lateritic soil increases liquid limit and plastic limit values but decreases the plasticity index values. Lateritic soil treated with nanosilica reduces the maximum dry density, MDD but increased the optimum moisture content, OMC.The unconfined compressive strength of the treated lateritic soil increased from 528 kN/m2 for the natural soil to peak value of 1135 kN/m2 at 1.5 % nanosilica content after 28 days of curing period. The coefficient of permeability decreased with increasing nanosilica content.Although, tests results showed noticeable improvement in engineering properties of the treated soil, the lateritic soil treated with extracted nanosilica can not satisfy the Nigerian General Specifications (1997) requirement of 1720 kN/m2 for use as road base course for lightly trafficked roads. It is therefore recommended that the extracted nanosilica can not be used as a stand alone additive, it should be used with a potent soil stabilizing agent like cement or lime.
Keywords: Laterite soil, Rice Husk, nanosilica, soil improvement
