Swelling Behavior of Electric Arc Furnace Aggregates for Unbound Granular Mixtures in Road Construction

Abstract

Artificial aggregates, which result from the treatment of electric arc furnace slags (EAF aggregates), represent a very interesting technological solution to replace natural aggregates in different road construction applications. In spite of excellent mechanical properties, the swelling nature of some expansive compounds present in their mineralogy could be detrimental to volumetric stability of civil works. In light of these considerations, the main objective of this research was to analyze the volume stability of different unbound granular mixtures composed by EAF aggregates (aged and fresh) through two accelerated swelling procedures: water-bath swelling test (ASTM D4792/D4792M-13) and steam test (EN 1744-1). The results demonstrated how the expansive developmental process follows, in general, three different progressive phases. Both expansion development and final swelling extent were a function of preliminary exposition to aging treatment and different physical factors, such as particle size, grain size distribution, and degree of compaction. The expansive behavior was more evident for fresh slag aggregates, which did not undergo any type of stabilization procedure. Specifically, the residual voids content, which is in close correlation with the degree of compaction, can be considered the main factor affecting swelling ratio. All specimens analyzed, however, showed appropriate expansion values according to ASTM and EN standard requirements.