Sustainability has become an important aspect of developed countries throughout the world. Sustainability is the ability to use byproducts and or waste materials from industry and recycle these materials in such a way that the application of the materials provides a beneficial use in the manufacturing or construction sector. As the United States and the rest of the world continue to grow, so too does the demand on the limited natural resources throughout the world. It is this demand on the resources that has brought the idea of sustainability to the forefront of research and design.
The transportation industry continues to incorporate sustainability into its projects. The industry is constantly trying new and innovative ways to recycle materials that would otherwise be sent to a landfill. Slag, a byproduct from the production of steel, is one of these materials. The transportation sector has used slags as aggregates for subbase and base layers in roads. Some slags, like blast furnace slag, have been used in portland concrete cement (PCC) applications as well. The focus of this research is to investigate the feasibility of using steel slag as an aggregate for use in portland concrete cement.
An important aspect of this research was to complete a comprehensive review of other research that has been conducted on the use of steel slag as an aggregate. The literature reviewed included of laboratory studies that focused on the physical, mechanical, chemical, and expansive characteristics of the steel slag. The research on the use of steel slag was gathered from 16 different countries, which include the United States, Spain, Japan, China, Germany, Finland, and Saudi Arabia. Some of these studies have found that properly treated slag may be non-expansive and used in PCC. The possible expansion of the steel slag is the most important characteristic. The expansion of the steel slag aggregate can have detrimental effects on a pavement. This research investigated some of the treatment processes that are being used to alter the composition of the slag so that it is no longer expansive. It also examines testing methods used to test for the expansion of the steel slag.
Seven State Department of Transportation specifications were also reviewed. Some DOT’s allow its use as an aggregate in asphalt pavements but do not allow its use in portland concrete cement. A review of the ASTM standards relating to the use of the slag as an aggregate was also completed in this study. Different slag associations like the National Slag Association and the Australian Slag Association were contacted during this research, as well as 19 different steel companies, to try and get an understanding of the public perception of the use of the steel slag as an aggregate in PCC, and also to try and locate possible case studies. Several case studies were identified, and two of them resulted in a failure of the pavement. In those cases it is unknown what, if any, treatment process was used on the slag prior to its use in the portland concrete pavement.