Brenner Autobahn: Strengthened by Renolith
The Brenner Autobahn
The Brenner Autobahn is a major European truck route that connects Innsbruck in Austria to Verona in northern Italy. Carrying more than ten million cars and two million heavy goods vehicles (HGVs) per year, it is one of Austria’s busiest highways. It is also one of Europe’s main north – south transit routes across the Alps. The area is subject to enormous fluctuations in temperature and powerful lateral water afflux at certain times of the year.
Project Need
The Brenner motorway surface between the 1st and 6th km suffered shoulder longitudinal cracking and formidable asphalt shrinkage and fatigue. Reconstruction of the south bound and north bound lanes was required.
Trial Road
A trial road was built in the Emilia-Romagna region of Italy to evaluate the performance of Renolith (aka NTS) compared to conventional road construction methods. The trial assessed the impact of the Renolith additive compared to cement-only stabilisation. The Renolith-treated side of the pavement performed well, while significant cracking developed on the untreated section.
Design and Construction
The subject section of the Brenner motorway was reconstructed over a 4-week period in March/April 2006. The existing bitumen courses were removed. The existing base layer was strengthened with a mix of coarse gravel, 25 kg cement and 2 litres of Renolith per m², to a depth of 30cm. A new asphalt wearing surface was applied.
Construction Benefits
The following advantages to the construction process were reported:
- the hardening process was accelerated; trafficable after 12h and able to lay asphalt after 24h.
- improved deformation modulus.
- Field of application improved because use in low temperature was possible (to minus 8°C).
The key benefits of constructing the base layer (ie. Excluding asphalt) using Renolith & cement compared to the conventional construction method (ie. Hydraulically bound gravel base course and frost protection layer) were realised as follows:
- Materials cost. Materials cost approximately 50% lower.
- Time & labour. More than 3 times faster to construct.
- Logistics & environment. 12,000 m3 gravel not required, saving 800 truck journeys.
- Higher bearing capacity (Ev2 = 1000 – 2000 MPa).
- Greater frost resistance. Considerably more durable.
As of 2022, roughly 30 million trucks and 150 million cars later, the pavement remains in service. No problems have been reported. No repairs have been necessary.
For more information, please see the Brenner Autobahn Case Study.