An investigation of the peculiar characteristics of laterite soils from southern Nigeria

Problem laterite soils are those that do not yield reproducible results using standard laboratory testing procedures. The soils are difficult to evaluate as engineering construction materials. The peculiar problems of these soils have been identified as thermal and mechanical instabilities i.e. the susceptibility to significant changes on the addition of small levels of thermal or mechanical energy. A laboratory investigation of the instability characteristics of laterite soils from the forest and savannah-woodland zones of Southern Nigeria has been carried out. Mechanical instability was determined by multiple compaction test and thermal instability by oven-drying under varying conditions. The results indicate that the soils studied can be unstable on the application of thermal and mechanical energies. Parameters obtainable from the grain-size distribution of soils subjected to the different conditions were found suitable for assessing thermal and mechanical instabilities. The maximum dry density and optimum moisture content obtained from the compaction curve are independent of the number of compaction.