The characterisation of foamed asphalt cement using a rotational viscometer

Warm mix asphalt using foaming technology is a widely used alternative to traditional Hot Mix Asphalt in the USA. However, there has been relatively limited research exploring the behaviour of the foamed asphalt cement, especially using traditional asphalt cement testing equipment. This research used the rotational viscometer to develop four new metrics that quantify the behaviour of foamed asphalt cement. These four metrics showed that increasing the foaming temperature increased the observed viscosity, but the initial observed viscosity decreased with lower asphalt binder grades. However, the point at which the observed viscosity crossed the actual viscosity increased with lower asphalt binder grades. Overall, the Wirtgen foamer had higher observed viscosity vs. the PTI foamer and provided a more robust foaming material. However, it is recommended that the AccuFoamer also be explored in future research, along with comparing laboratory produced foamed asphalt cement with field produced foamed asphalt cement.