Behavior of a Hot Mix Asphalt Using Gilsonite and Recycled Concrete Aggregate

Abstract

The replacement of natural aggregates (NA) with recycled concrete aggregates (RCA) can be seen as a technique that is environmentally friendly. On the other hand, in high temperature climates, rigidizing asphalt using Gilsonite (G) can be seen as a viable technique for increasing rutting resistance in hot mix asphalts (HMA). This study replaced in mass, part of the coarse fraction of NA with RCA (substitution of 12.5%, 21% and 43%) of an HMA that used asphalt that was modified by wet process with G (AC-G). In regards to mixes, resistance under monotonic load was evaluated (Marshall and Indirect Tensile Strength - ITS tests), tests for evaluating moisture damage resistance (tensile strength ratio - TSR) and abrasion resistance (Cantabro test). An ANOVA variance analysis was carried out in order to analyze if RCA and G have statistically significant effects on the properties of HMA. A general conclusion was reached that when replacing NA with RCA up to 21% (particles of 1/2”+ 3/8”), mixes comply with quality requirements demanded in the HMA design. However, RCA tends to reduce the evaluated resistance parameters and to increase the optimal asphalt content required (OAC). Despite this, the response of evaluated resistance parameters improved significantly when mixes were manufactured with AC-G.

Keywords: hot mix asphalt, recycled concrete aggregate, RCA, gilsonite, asphalt modified