The Influence of Water Foaming and Ageing on the Properties of Bitumen 50/70

Abstract

Water-foaming of bitumen produces a binder that allows half-warm mixture manufacturing and incorporation in upper pavement layers at 100°C to 130°C. During the foaming process, cold water and air are injected into hot bitumen at 160-170°C. As a result, the bitumen is exposed to the action of oxygen and hydrogen. The influence of the foaming process on bitumen 50/70 and SAA modified bitumen 50/70 at 0.6% was evaluated based on the binder pre- and post-foaming properties and the ageing effect. For this purpose, the basic foaming parameters, i.e., expansion ratio and half-life, were determined, along with the penetration at 25°C, softening temperature, Fraass breaking point, and dynamic viscosity at 60°C (maximum in-service temperature), 90°C (compaction temperature) and 135°C (the temperature at the start of traditional asphalt mixture incorporation). The fracture creep stiffness was determined using the Bending Beam Rheometer. Analysis of the results showed that the process of bitumen foaming with water significantly affected the basic and low-temperature properties of the bitumen. It was also found that, compared to the non-foamed binder, foaming slowed the rate of binder ageing.