Recent improvements in quality of steel slag aggregate

Steel slag aggregate has been used in premium surface course hot-mix asphalt for Ontario highways since the early 1970s. Asphalt pavement performance problems led to the Ministry of Transportation imposing a moratorium on the use on steel slag aggregate in late 1991. The problem has been addressed from the steelmakers producing the slag to hot-mix design and production. Steel slag can serve as good aggregate for use in hot-mix asphalt if the volume expansion of the slag is controlled. Performance-based testing of steel slag aggregate, particularly volume stability, is recommended as a measure of the aggregate quality. Practices at the steelmaker and the slag processor were examined. The production of acceptable quality steel slag aggregate requires total quality management of all steps of production.