Fibre reinforced asphalt

Fibre reinforced asphalt is asphalt to which small, very strong fibres — usually aramid or PAN — are added during production to slow down cracking, ravelling and rutting. It is an alternative to polymer modified bitumen (PMB) and reinforcement mesh, with comparable or better field performance against generally a lower environmental impact. On this page we bring the knowledge together: what fibre reinforced asphalt is, how it works, how it compares to PMB, and what it means for costs, environmental performance and tendering. The in-depth articles below each work out one part in more detail.

How fibre reinforcement in asphalt works

Asphalt consists of aggregate, sand, filler and bitumen as a binder. Under the influence of traffic loading, temperature fluctuations and ageing of the binder, cracking, ravelling (loosening of aggregate) and rutting (indentation from tyre loads) eventually develop. Open-graded mixes such as porous asphalt (ZOAB) are particularly susceptible to this, because the stone skeleton has less mutual contact than in dense mixes.

Fibres are added dry to the aggregate, well before the bitumen, and once distributed through the mix work at microscale as three-dimensional reinforcement: they bridge microcracks (crack bridging), distribute the traffic load better across the mix and hold the mortar bridge between the stones more firmly against ravelling. Aramid fibres — aromatic polyamide — combine very high tensile strength with heat resistance, chemical inertness and low elongation: precisely the properties needed to keep asphalt intact for longer. Even in heat, when the binder softens, the fibres retain their strength and so reduce the likelihood of permanent rutting.

Fibres versus PMB: production and temperature

Traditionally, asphalt is reinforced with polymer modified bitumen or with reinforcement mesh. PMB is harder to recycle and requires a higher production temperature; reinforcement mesh requires a separate, time-consuming operation. Fibre reinforcement combines the best of both: a standard penetration-grade bitumen suffices, and no separate reinforcement layer is needed.

Because penetration-grade bitumen is naturally less viscous than PMB, the mix can be produced at a lower temperature — in field trials on the A73, around 15 to 20°C lower. That means less energy use at the asphalt plant, fewer fume emissions during laying and a better working environment for road crews, without compromising on compactability or mix quality.

Environment, standards and certification

The sustainability advantage is now also measurable. The life-cycle assessment carried out within the European FIBRA project found that the PMB mix had the highest environmental impact at cradle-to-gate level — more than a 10% difference on the Environmental Cost Indicator (MKI) compared with the aramid variant. Since 1 July 2026, the PCR Asphalt 2026 determines how the environmental performance of asphalt mixes is calculated uniformly, with a revised energy model that more clearly credits the lower production temperature of fibre mixes.

The environmental-hygiene side is equally regulated. Additives must appear on the OPWA list to be dosed without additional leaching research under an NL BSB® certificate (BRL 9320). AsphaltX® is on that list, with a maximum applicable percentage of 0.1% — well above the recommended dosage of 500 grams per tonne (0.05%).

Costs, tendering and field evidence

The direct premium for fibre reinforcement is limited: the cost sits mainly in the fibre itself, not in an extra work step. Research within FIBRA shows that fibre reinforcement can work out cost-neutral compared with PMB in the Dutch situation, provided a comparable service life is achieved — and viewed over the service life, the potentially longer lifespan of the road surface counts in its favour. Anyone wanting to capture those benefits includes fibre reinforcement explicitly in the tender, preferably specified functionally on environmental performance, service life and production experience.

The evidence comes from the field. On the A73 near Roermond, BAM and Rijkswaterstaat, within the FIBRA project, built a trial section with four variants of the same porous-asphalt surface course, where the fibre variants performed comparably to the PMB reference mix after three months of traffic loading — at a 15 to 20°C lower production temperature and a lower environmental impact. These test sections are monitored over the long term. The articles below each work out one of these topics in more detail.