The OPWA list: BRL 9320 and NL BSB for asphalt additives
Asphalt falls under the Dutch Soil Quality Decree; an additive must be environmentally approved. The OPWA list regulates this — AsphaltX® is on it.
Asphalt is more than stone and bitumen. Fillers, rejuvenators, pigments and fibres all help determine the performance of the mixture — but cannot simply be applied at will. Since the introduction of the Dutch Soil Quality Decree (Besluit bodemkwaliteit) in 2008, an asphalt producer must be able to demonstrate that its bituminous mixtures are environmentally safe. The NL BSB® product certificate based on BRL 9320 provides that proof.
What is the OPWA?
The OPWA — in full, Omschrijving Productgroep Warm Asfalt (Description of the Hot Asphalt Product Group) — is the document that sets out, per constituent building material, in what quantity it can be safely applied in hot asphalt, for both shaped (V) and unshaped (N) materials such as porous asphalt (ZOAB). The list is maintained by the Centrale Organisatie TOP and is based on environmental analyses of asphalt mixtures dating from 1999 to the present. The current version can be found in the downloads section at top-advies.nl.
For every category — aggregate, sand, bitumen, filler, additives and pigments — the OPWA states a maximum applicable percentage and a reassessment date. If an additive is not on the list, environmental research is required on an asphalt mixture containing that material before it may be produced under NL BSB.
Why this matters for asphalt plants
For an asphalt plant, the OPWA list is in practice the fastest route to certainty. An additive on the list can be dosed within the stated range without additional leaching research — the groundwork has already been done. That saves lead time, research costs and discussion with the certifying body.
The listing is also relevant for clients and specification writers: they know that a mixture with an OPWA-listed additive simply falls under the producer's NL BSB certificate.
AsphaltX® is on the OPWA list
AsphaltX® is included in the OPWA under the additives category, with a maximum applicable percentage of 0.1% in both N and V materials and a reassessment date running until mid-2031 — longer than many other additives on the list.
That 0.1% corresponds to 1 kg per tonne of asphalt. Our recommended dosage of 500 grams per tonne (0.05%) is comfortably within that. Asphalt plants can therefore process AsphaltX® without additional environmental research in their NL BSB-certified mixtures — for porous asphalt (ZOAB), SMA and dense asphalt alike.
Getting started with fibre reinforced asphalt?
Want to know what fibre reinforcement means for your mixture or project? View the AsphaltX® product page with datasheet and reference projects, or contact our advisers for dosing advice and specification texts.