STEEL SLAG UTILIZATION IN ASPHALT MIXES

Abstract

Steel slags are the major byproduct from the conversion of iron to steel in the basic oxygen (major type), electric arc and open hearth (minor type) steelmaking processes. Steel recovery from the slag results in a processed aggregate with both positive (wear resistant, skid resistant, rough textured, angular, well graded, stripping resistant) and negative (heavy, expansive) features. Considerable experience, particularly since 1970 in Southern Ontario, has shown that the use of steel slag in asphaltic concrete minimizes potential expansion and takes advantage of the positive features in giving high stability, stripping resistant asphalt mixes with excellent skid resistance. (It should be noted that steel slag must not be used in confined applications or Portland cement concrete.) The high stability of steel slag mixes offers a distinct advantage where rutting resistance is required and this has been demonstrated in industrial areas. The excellent skid resistance provided has been monitored in both urban and highway applications, and steel slag asphalt mixes (open and dense graded) are often used for critical pavements. While these positive applied features of steel slag asphalt mixes are emphasized, practical design guidance is also provided covering special features that must be dealt with to ensure satisfactory performance such as uniformity, deleterious materials, unit weight and potential expansion. It is clear that steel slag will continue to make a positive contribution to high quality asphalt mix aggregate requirements in areas of steel production.