Microstructural investigation on laterite soils

Considerable researches have been carried out to demonstrate the importante of microstructure in the interpretation of engineering behaviour of soils. Instances where the investigations are on laterite soils are however scanty in literature. The microstructure of laterite soils obtained from Eastern Nigeria and North-East Brazil, have been examined with the aid of optical and scanning electron microscopes. Investigations reveal the development of the well-known concretionary structure in laterite as a stage by stage process involving the accumulation of sesquioxides. The sesquioxides are accumulated initially as amorphous implantations in the pore spaces, the crystallisation of which leads to bonding of soil elements and formation of concretionary structure. The nature of cementation in the concretionary structure determines the resistance to degradation of the soils grains. The resistance to degradation would in turn influence the engineering behaviour.