Steel Slag Aggregate Used in Portland Cement Concrete: US and International Perspectives

The issue of sustainability in the built environment is increasingly important, particularly in the transportation sector. In some cases slags from the iron and steel industries can be used to replace natural aggregates in construction. In this research, laboratory investigations of the use of steel slag as a portland cement concrete (PCC) aggregate were reviewed. Much of this research took place outside the United States. Some limited field cases of the use of steel slag in pavements were found. In at least two cases dramatic pavement failure resulted, but it is not known whether the slag used in the applications had been properly aged as required by modern specifications. Research on the use of steel slag aggregate in PCC has been carried out in Spain, Germany, Canada, Italy, India, and Saudi Arabia. Despite some limited field applications, virtually all research has been done in the laboratory. Much of this work shows that properly aged steel slag can be nonexpansive when used in PCC. When these research results are evaluated, it is important to consider the properties of the slags used because they may differ from the slags produced in the United States due to differences in sources or industrial processes. Several state department of transportation specifications were reviewed, and they generally do not permit the use of steel slag as a PCC aggregate. Steel slag represents a small part of the total aggregates currently used, but it is an alternative material that should be considered where it makes economic sense.