The Mechanism of Binder Distribution in Foamed Asphalt Mixture

Abstract

The key issue in understanding foamed asphalt properties is that of binder distribution which a result of mixing process is. It is therefore the mixing process is the most important factor in foamed asphalt production (in combination with good foam properties). Following the mixing process the foam distributes onto fine aggregates forming larger particles of various sizes, for which the most binder rich is found to be at 2.36mm size for this sample (FWC of 4%). These binder rich ‘particles’ mainly consist of fine aggregates (largely filler) and the maximum coated aggregate size is 6.3mm. The mechanism of binder distribution, which has to be well understood in order to know the characteristics of foamed asphalt mixture, has been fully described. It is found that the binder formation is that of a combination of bitumen and fine aggregate, forming particles that distribute across the aggregate phase. The properties of these binder-fines particles become crucial during mixing process. The workability of binder-fines particles influences the uniformity of the binder distribution. A uniform mixture in terms of binder distribution will potentially achieve high performance.