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DID YOU KNOW? Around 90% of Road Science’s business involves public roads – the balance comes from the private sector. A recent private sector project involved the surfacing of a new, 4.8km international-standard motor-racing circuit near the Otago town of Cromwell where Road Science’s materials, forensic and design expertise were critical in the circuit’s surfacing. The job required 13,500 tonnes of asphalt, a large portion of which was polymer-modified using Road Science technology. asphalt, the road surface was able to flex and better resist cracking. Fatigue testing showed that conventional asphalt cracked at about half a million cycles of repeated loading and unloading – but the Road Science polymer blend was still going strong at 12.5 million cycles. Veenay Rambisheswar, Manager, Programme & Development Services, says the innovation has delivered “a huge benefit in terms of the road having a longer life … it’s all about sustainability and getting the most out of existing infrastructure”. Road Science is also taking a closer look at the base course – the layer under the seal, usually crushed greywacke in New Zealand. The New Zealand Transport Agency specifies the base-course ‘recipes’ for all of its roads. However, says Greg Arnold, Technical Manager Pavements, it’s costly to truck in aggregate, so Road Science investigates local alternatives and tests their strength in the lab. When an airstrip in the Solomon Islands needed reconstruction, Road Science researched local resources and came up with a base course of crushed coral. “We try to use local materials while still getting performance – that’s the name of the game,” says Arnold. Take the remote Taihape-Napier road. A 21km stretch was slated for sealing, but the nearest specified rock was 100km away, and trucking it in posed environmental and road-damage risks. Road Science tested local rock with various binders, such as lime and cement, and came up with a mix that, under testing, performed as well as the specified aggregate. Using rock close to hand saved the customer councils, Rangitikei and Hastings, $1 million. Road Science works with the NZ Transport Agency on updating its specifications. Company testing found that using crushed glass as base-course filler didn’t impair performance. The NZ Transport Agency now permits up to 5% of base course to be composed of crushed glass, with higher levels permitted as long as testing shows no deterioration in performance. With so much innovation underway, education is an important part of the new Road Science service, says General Manager Phil Muir. “It’s not just about teaching people how to use these products – we need to take everyone back to the basic science involved. It’s all part of the recipe that will give New Zealand a network of better, more cost-effective roads.” DOWNER / IN BLACK & WHITE / 39


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