Laboratory Investigation of Reclaimed Asphalt Pavement Mixedwith Pure Binder Using X-ray CT Scanner

摘要

The use of reclaimed asphalt pavement (RAP) has proven to be economicalrnand environmentally safe as being used extensively to produce new asphaltrnpavements. To examine the “black rock” problem of RAP material, a laboratoryrninvestigation was conducted in this study in which the blending process of simulatedrnand actual RAP material with virgin binder was analyzed using an x-ray scanner. Forrnthis purpose, new aggregate was mixed with virgin binder containing 25% metalrnpowder (by weight) at 4.5% asphalt content, and then the mixture was oven aged tornsimulate the RAP binder. Subsequently, the simulated RAP material was again mixedrnwith new binder, without metal powder, to observe if the metal powder from thernaggregate surface will combine with the added binder. Also, virgin binder with 25%rnmetal powder was mixed with actual RAP to detect any dispersion of the powder intornthe asphalt film. Cross sectional images from the x-ray CT scanner indicated that thernmetal powder has diffused from and into the asphalt film of the aggregate particlesrnduring the blending process. Thin layers (microlayers) of metal powder, with varyingrnthicknesses, were observed in the vicinity of the aggregates’ surfaces due to x-rayrndiffraction. The results provide clear evidence that simulated and actual RAP bindersrnpartially blend with the virgin binder to a certain extent.