System for Processing of Reclaimed Asphalt Planings (RAP) for High Percentage Incorporation of RAP in new lay road surfaces (Infrarap)

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Currently, asphalt removed from a road is stockpiled for later use as aggregate for new hotmix asphalt (HMA) at an asphalt plant. This reclaimed material, commonly known as RAP –recycled or reclaimed asphalt planings, is crushed to a consistent gradation and added to theHMA mixing process. Asphalt consists of 95% aggregate and 5% bitumen, both of which arevaluable resources with high embedded energy and CO2 footprint.Several in-situ and ex-situ recycling techniques exist for asphalt recycling the most commonof which introduces RAP using a cold feed which bypasses the drying drum. Due to the highmoisture content, very low volumes (~20%) are re-used at a significantly high energy costbecause the virgin aggregate must be heated to 200-300 deg C. There are also significantissues with the quality of the final product as the aged bitumen binder is damaged by the hightemperature needed to dry the virgin aggregate and becomes susceptible to UV degradationand is rendered liable to early stone loss and cracking.The Infrarap project aims to develop a system for processing RAP so that higher percentagescan be incorporated into paving materials and especially into the wearing course layer. Thesystem will comprise adaptable heating, mixing and conveying systems which will feed RAPat an optimum low temperature into elevating skips or direct to a mixer-feed chute via aconveyor of a static mixing plant or a mobile mixing plant using an efficient rejuvenatorwhich will allow high percentages of RAP to be recycled into asphalt mixes at lowtemperatures.The development follows some preliminary investigations into current methods ofincorporating RAP into mixes, including alternative systems. There is a clear market need foran independent method of heating and directly feeding RAP into the pug-mills of mixingplants that bypasses a drying drum and obviates all adverse issues with scorching RAP andblocking filters and screens.