New developments with half-warm foamed bitumen asphalt mixtures for sustainable and durable pavement solutions

Internationally, a growing health, safety and environmental awareness of the public can be observed. In this context, significant efforts are underway to develop advanced technologies to reduce the use of non-renewable fossil fuels, in order to reduce emissions and human exposure. Also, in the road industry, the search for new sustainable solutions is eminent. The introduction of asphalt mixtures that can be produced at lower temperatures is an important development in this direction. Lower temperature means in general that lower than 140°C. In this article, developments with the so-called half-warm foamed bitumen mixtures produced at temperatures below 100°C and even as low as 90°C are discussed. Mixtures used in binder and base layers are considered. The role of life-cycle assessment as used in the Netherlands is described for half-warm foamed bitumen mixtures. The performance properties according to the CE marking are also discussed at the same time. Finally, the workability of these mixtures is studied, showing how compaction of this type of mixtures can be managed. In all cases, a reference hot base course mixture is used for comparison.