Tarmac’s high-performance ULTILAYER 6mm SMA was outlined as the solution to the surface cracking and deformation that had occurred on North London’s Addison Avenue.

The Challenge
Regular trafficking and on street parking had caused surface cracking and deformation on this residential avenue in North London. Core sample reports showed that the existing hot rolled asphalt surface had been laid on top of an unbound sub-base. They also indicated layers of tar bound asphalt in the upper layers of the road construction. The potential for instability in the base would increase the risk of future cracking and presented a challenge for highways engineers when resurfacing the road. Removal of the tar bound asphalt and specialist disposal or encapsulation using insitu recycling would have been costly and time consuming. It would also have been disruptive for residents due to extended road closures and additional vehicle movements.

Tarmac’s Solution
After discussions with Tarmac’s Technical Product Support Manager, ULTILAYER 6mm SMA, Tarmac’s high-performance polymer modified asphalt was identified as a solution. ULTILAYER combines outstanding flexibility and strength to deliver long term durability, even on the most difficult sites where conventional materials have failed. The advanced polymer modified binder would provide enhanced flexibility and durability needed to cope with vehicle manoeuvring, static loading from parked cars and any underlying movement in the sub base. ULTILAYER can be laid in a single layer, to replace the surface and binder course. This enables faster resurfacing but also accommodates the restrictions in pavement depth that are a frequent challenge when resurfacing residential streets.

Results and Benefits
As planned, the existing surface was planed out to 30mm and around 250 tonnes of ULTILAYER 6mm SMA was supplied and laid. The innovative approach chosen by Enfield for this resurfacing scheme, allowed work to be completed quickly in just three days with minimal loss of access or disruption to local residents. Significant cost savings were achieved by avoiding full depth reconstruction. Fewer outbound and inbound vehicle journeys were also a welcome advantage given the sites proximity to the busy North Circular Road. No complaints were received by the council for the duration of the resurfacing work and the new 6mm surface also provided a smooth even finish and a quieter surface for householders living on the Avenue.

Client: London Borough of Enfield
Contractor: Marlborough Highways
Completion: Aug 2019