Improving the geotechnical properties of spent ore with laterite for road pavement construction

Abstract

Heap leaching generate large volume of spent ore and due to its potential toxic nature, it is contained and not exposed to the environment. The spent ore can be reused as a construction material especially for road construction. However, due to its granular nature, it is difficult to compact the materials to achieve the required strength for geotechnical purposes. The geotechnical properties of the spent ore can be improved by addition of other materials. Laterite was used to improve the geotechnical properties of spent ore for the construction of base and subbase of road pavement. The laterite was added to the spent ore in range of 10% to 50% to form composites. Physical and engineering laboratory tests including, Atterberg Limits, Compaction and Californian Bearing Ratio (CBR) were conducted on the composites in accordance with British Standards. The results showed that addition of laterite from 10% to 20% resulted in Liquid Limit (LL) between 20% and 22%, the values are within the specifications for the Ministry of Transport specification for base and subbase materials. The compaction test on the composites resulted in Maximum Dry Density (MDD) between 1.3 g/cm3 and 2.01 g/cm3. The soaked CBR values fell between 32% and 62%, the unsoaked values were between 31% and 64%. The composite 70% Spent Ore and 30% Laterite recorded the highest soaked and unsoaked CBR value of 62% and 64% respectively. The results showed that, 30% addition of the laterite would improve the spent ore for only subbase construction. Further studies is recommended for the improvement of the geotechnical properties of spent ore for base construction.