Pozzolana-cement stabilisation of a black cotton soil from Ghana

摘要

The paper discusses results of laboratory studies on the stabilisation of an expansive black cotton soil from the Accra Plains of Ghana using pozzolana-cement admixture. The admixture was prepared by mixing one part of calcined clay pozzolana to two parts of ordinary portland cement by weight. The soil was then blended with 0%, 3%, 6%, 9% and 12% pozzolana-cement by weight of dry soil. The composite materials were then subjected to geotechnical engineering tests namely; grading, Atterberg limits, compaction and California Bearing Ratio. Results of the study show that, the addition of pozzolana-cement to the soils had no significant effect on the general particle size distribution. There was general reduction in the Atterberg limits (liquid limit, plasticity index, linear shrinkage) except the plastic limits which increased slightly with increasing pozzolana-cement content. The maximum dry density increased 4% whereas optimum moisture content decreased by about 21%. The California Bearing Ratio values also increased from no strength to about 9% at 12% pozzolana-cement content whereas the minimum CBR-swell of 14% occurred at 3% pozzolana-cement content. The pozzolana-cement caused significant improvement in some geotechnical properties of the soil particularly, the bearing strength and has soil improvement potentials.