Incorporating rubber-modified bitumen into roading operations is already business as usual for Fulton Hogan across the Tasman. That experience has positioned the company well to become an early adopter of the technology in Aotearoa New Zealand.
Its story here tracks the three barriers the action plan identifies: supply, procurement demand and research. Bryan Pidwerbesky, Technical Director for Pavements, has spent 40 years in New Zealand roading. Fulton Hogan embraced crumb rubber when it expanded into Australia 25 years ago, where it had already been used in sealing for decades. “The Australians recognised the benefits of crumb rubber in bitumen and how it improves the life of the seal.”
The company’s first New Zealand use was an asphalt trial nine years ago, backed by a Waste Minimisation Fund grant. The bitumen left the plant in Tauranga, was blended with imported crumb in Auckland and driven to Wellington to be mixed and laid. “There was no one in New Zealand producing crumb rubber to the standard we needed.”
The first crumb rubber chipseal came this year, on a quarry road Fulton Hogan operates in Selwyn, chosen so the team had total control and no public traffic to manage. Australian colleagues came across to make sure the work followed best practice, and Fulton Hogan adopted the Australian specifications as they stand, since they already allow for the softer bitumen that colder South Island conditions need. The seal is being monitored.
The main change in the last twelve months, Bryan says, is a reliable, consistent, good-quality local supply of crumb. Quality is specific: consistent sizing, compatibility with the bitumen, and no metal, which wears out nozzles and pumps. Locally made crumb could replace up to 16% of the bitumen New Zealand imports.
The benefits are longer seal life, flexibility, less cracking and less flushing in summer, and lower whole-of-life cost despite higher setup costs. The work ahead is research: NZTA currently specifies emulsion seals on state highways because they are sprayed at lower, safer temperatures, while crumb rubber currently needs heat. “If we can get crumb rubber into emulsion, I’ll be very happy…it means operating at a safer working temperature.”