Speaker
Description
Abstract. Cold recycling is a technology used in constructing or rehabilitating flexible pavements. It strives to optimise the performance of processed reclaimed materials and construction methods, in order to gain environmental and economic benefits i.e. reducing carbon footprint whilst improving pavement life. The technology leads to the production of Bitumen Stabilised Materials (BSMs), a base layer that provides sufficient bearing capacity for a spectrum of moderate to very high volumes of traffic. Key considerations for sustainability of BSMs include durability i.e. resistance to moisture damage of materials, and performance i.e. appropriate materials to withstand the traffic loading and environment whilst achieving the design pavement life. This study comprises a combination of three separate research projects, covering BSM mix types and compositions as well as compaction techniques. The two different mix types are BSM-foam, where foamed bitumen is injected to the mix and BSM-emulsion, where the bitumen is emulsified before being dispersed in the mix. In addition Reclaimed Asphalt or RA is included as one of the mix component variables. Three laboratory compaction methods i.e. vibratory, gyratory and falling weight, are utilized in preparing specimens for testing. The compacted specimens were evaluated for the achieved densification, as well as ITS tensile strength and triaxial properties i.e. Cohesion and Friction Angle. The findings show that the application rate of RA in the BSM mix influences the moisture resistance positively and hence durability. Low RA contents provide mixes that perform well with vibratory compaction due to the packing mechanism, whilst high RA contents prefer gyratory compaction, due to the kneading effect. Triaxial tests show that a balance between shear strength and moisture resistance need to be considered in mix designs. In addition, QC can be effectively carried out on the jobsite by stacking 2 or 3 specimens for triaxial testing as opposed to ITS tests being used.
