Environmental and technical assessment of ferrochrome slag as concrete aggregate material

Ferrochrome slag is a major solid waste generated from submerged electric arc furnaces during manufacturing of ferrochrome alloy. The waste slag has excellent mechanical and engineering properties for utilization as concrete aggregate material. But it contains about 6-12% of residual chromium which has the potentiality of releasing hazardous chromium compounds to the environment. This research work carried out the mineralogical and chemical characterization study to find out the major chemical elements and mineral phases in the solid slag matrix. Physico-mechanical experimental studies indicated the suitability of the slag as aggregate material in concrete work. The concrete product with ferrochrome slag as coarse and fine aggregate showed excellent results with respect to compressive strength and were found to be suitable for general purpose concrete work. The standard leaching experimental results showed that the leachable chromium remains well immobilized in the cement and concrete matrix with very low to non-detectable level of chromium leaching. The results indicated the technical acceptability and the environmental compatibility of the slag as concrete aggregate material.