Generally, asphalt mixtures intended for wearing surfaces subject to heavy traffic are made on the basis of polymer-modified binders. Their production requires high energy consumption. Warm mix asphalt (WMA) technologies are an excellent solution for fulfilling these requirements. Foaming based WMA have shown great potential in reducing the mixing and compaction temperature of asphalt mixtures by decreasing the viscosity of the binder. Foaming based WMA can be obtained by adding to the binder water-bearing additives such as zeolites. This paper presents the results of a study of two zeolite additives differing in their crystal structure for polymer modified bitumen binder (PMB 45/80-55): one is natural zeolite of the clinoptilolite type, and the other is synthetic zeolite Na-P1 produced from fly ash. Both additives, previously soaked with water, were added in amounts of 5% by weight of the modified binder. Based on the results, obtained from the conducted tests (i.e. softening point, penetration, dynamic viscosity and cohesion), it was concluded that both zeolites do not significantly affect the viscoelastic properties of PMB 45/80-55. Only the effect on cohesion was observed, indicating that the binder becomes stiffer, making the pavement less resistant to cracking. It was determined that from the perspective of the impact on the viscoelastic properties of the modified binder PMB 45/80-55, the best solution is to use a natural zeolite of the clinoptilolite type. The test results obtained on modified bitumen with the addition of zeolites were compared to the results of modified binders with styrene–butadiene–styrene copolymer (SBS) and crumb rubber (CR). It was found that modified binders with SBS and CR shows comparable properties to zeolite-modified bitumen.

warm mix asphalt;natural zeolite; synthetic zeolite; modified bitumen