Influence of Clay Mineralogy on Plasticity of Lateritic Soils

Abstract

Lateritic soils samples taken from four different locations were subjected to plasticity tests and clay mineralogical analysis using method of X-ray diffraction. The results of the plasticity test of the soils indicate liquid limit values of the soils ranging between 35.00 to 52.30 %. The plasticity index and linear shrinkage of the soils ranges from 15.73 to 24.70 % and 8.21 to 16.64 % respectively. The clay mineralogy results show three of the soil samples, having lower plasticity values, consisting of mostly kaolinite as clay mineral, while the soil having relatively higher plasticity value (liquid limit of 52.30 %, plasticity index of 24.70 % and linear shrinkage of 16.64 %), shows presence of a mineral of the chlorite group as the dominant clay mineral. This shows that the relatively lower and higher water affinity of kaolinite and chlorite respectively, present in this soils were responsible for the recorded plasticity values.