Electric arc furnace slag as aggregates in semi-dense asphalt

Abstract

Electric Arc Furnace Slag (EAFS) is one of the primary by-products of the steel recycling industry, which comes out initially as large pieces, that can be further crushed and be used as aggregates in infrastructure materials. While being a waste product, the relatively high strength of the aggregates means that EAFS can provide favorable properties when used correctly. One possible destination for EAFS of higher value is semi-dense asphalt (SDA), a surface course used as low-noise pavement. Due to the relatively high percentage of air voids in SDA (10–18%), the mixture mechanical properties depend on strong interlocking of the aggregates. This study looks at the incorporation of EAFS fractions (2/4 and 0.125/2 mm) into SDA 4 mixtures at replacement of 13% by volume of the aggregates. These mixtures are compared to the control mixture with sandstone aggregates in terms of volumetrics, water sensitivity, stiffness modulus and fatigue by cyclic indirect tensile loading, along with permanent deformation by the cyclic compression test. The water sensitivity, rheological properties and fatigue resistance of the EAFS mixtures did not vary significantly from the control. The life cycles assessment (LCA) shows that compared to the reference SDA, the EAFS-modified SDA reduces the greenhouse gas emissions and ecological scarcity eco-points by 40% and 90%, respectively due to the avoidance of EAFS landfilling. However, the non-renewable cumulative energy demand is not improved by using EAFS in SDA, due to the additional consumption of bitumen.

Keywords

• Semi-dense asphalt (SDA)
• Electric arc furnace slag (EAFS)
• Fatigue
• Modulus
• Water sensitivity
• Life cycle assessment (LCA)