COMPACTION CHARACTERISTICS AND WORKABILITY OF THE LATERITIC SOIL-IRON ORE TAILINGS IN PAVEMENT CONSTRUCTION

Abstract

The mining waste deposit such as iron ore tailings (IOT) in Nigeria is a menace to the environment by constituting a nuisance to the mining industry, and its effect on lateritic soil as a compaction and plasticity reduction material for road pavement is considered in this study. The used natural lateritic soil was classified as A-7-6(11) or CL by the American Association of State Highway and Transportation Officials (AASHTO) and Unified Soil Classification System (USCS) respectively. Up to 16% of the soil’s dry weight was modified with iron ore tailings (IOT). Studying the effects of IOT on the altered soil focused on its cation exchange capacity, plasticity, compaction properties and California bearing ratio (CBR). British Standard Light (BSL) energy was used for the compaction process. However, the results of regression analysis showed that the optimum moisture content had a substantial impact on the soil CBR values. The results of the tests show that as the IOT content increased, plasticity and compaction characteristic values increased. Although an optimal 10% IOT treatment of lateritic soil significantly improved its strength properties, the plasticity characteristics recorded exceeded the requirement specified by the Nigerian General Specifications for direct use as a subbase or base material. Thus, reusing 10% iron ore tailings as filling materials required additional percentages of other pozzolanic materials to lessen the environmental problems associated with their deposition.