Feasibility of copper slag-fly ash-soil mix as a road construction material

The use of waste materials in the road construction industry is gradually gaining significance in India, considering disposal and environmental problems and the gradual depletion of natural resources. The copper unit located at Dahej, Gujarat, India, produces 1,200 to 1,500 tons of copper slag per day. The large quantity of accumulated slag is dumped and left for the most part unused on costly land within the plant premises. Also, 50 to 100 tons of fly ash are produced per day from the existing captive thermal power plant. The potential use of these materials in road construction was studied initially by evaluating the materials for their physical and chemical characteristics. The waste materials were mixed with local soils in the range of 25% to 75%, and their geotechnical characteristics were investigated. The feasibility of using these mixes in the base course of road pavement was investigated by adopting stabilization techniques. The potential of copper slag as a replacement for fine aggregates in bituminous mixes was also investigated. It was concluded that a mixture of copper slag, fly ash, and soil has the potential for use in embankment, subbase, base, and wearing courses of road pavement. The results of laboratory tests and typical technical design specifications indicating the utility of copper slag, fly ash, and soil in different layers of road pavement are discussed.