Steel furnace slag aggregate expansion and hardened concrete properties

Steel furnace slag (SFS) is an industrial by-product that is not commonly utilized in bound applications because of its potential to contain high contents of free calcium and magnesium oxides, which expand when hydrated. In this study, a process was developed to quickly screen SFS aggregates for free oxide contents and expansion potential using complexometric titration, thermogravimetric analysis, and an autoclave expansion test. Two of the three SFS aggregate sources (high and low expansion) were selected for testing as a coarse aggregate in concrete. It was confirmed that SFS aggregates in concrete can produce acceptable strength properties, suitable freeze/thaw durability, and exceptional fracture properties. However, these SFS aggregates produced greater free drying shrinkage than concrete with dolomite aggregates. For SFS aggregates having low expansion potential, the hardened property tests indicate that SFS may be a suitable aggregate for concrete.