Mechanism of asphalt concrete reinforced with industrially recycled steel slag from the perspectives of adhesion and skeleton.

This research investigated the reinforcement mechanism of steel slag recycling in asphalt concrete from the perspective of adhesion and skeleton. Bonding performance between steel slag and bitumen was assessed by the calculation of coating area and peeling area, as well as the area detection by Scanning Electron Microscope (SEM) and Energy Dispersive Spectrometer (EDS). Computed Tomography (CT) scanning was used to determine the bitumen absorption characteristics of steel slag. Mechanical characteristics of steel slag mixture during compaction period and service period were evaluated by continuous compression test with Universal Testing Machine (UTM-25). A combination of CT scanning and image processing technology were used to quantify skeleton contact characteristics. The results indicated that bonding performance of bitumen with steel slag was obviously better than basalt after long-term erosion. The surface pores of steel slag absorbed excessive bitumen as anchoring and embedding effect, accounting for 20.24% of the total steel slag bitumen absorption in maximum. Steel slag skeleton of SMA gradation was found easily to be compacted during construction period and more resistant to loading during service period. In addition, there were more contact points in steel slag asphalt concrete, resulting that steel slag asphalt concrete had better stability. The contact points were different in different particle size ranges, and it was suggested that steel slag with particle size of 9.5–16.0 mm and 2.36–4.75 mm should be preferred. • Bonding of bitumen with steel slag was superior to that of basalt after long-term erosion. • Pores on surface of steel slag result in excessive bitumen adsorption, accounting for over 20% of steel slag bitumen adsorption in maximum. • Steel slag skeleton can better resist external loading to prevent early rutting diseases. • Steel slag asphalt concrete had better skeletal contact characteristics, while gradation type has greater influence than particle type. [ABSTRACT FROM AUTHOR]