Downer leads bitumen world first

Replacing the toner cartridges in the photocopiers of every office is a common occurrence. But what happens to the cartridges?
They are sent to Croxley's toner recycling centre in Auckland. Each cartridge still retains some waste toner, a fine dusty powder, and it is removed, sealed in a cube and dumped in a landfill, at a cost.
Downer's laboratory in Tauranga has, instead, come up with an environmental solution.
Following ground breaking research, Downer has found the waste toner can be added to polymer modified bitumen and used in laying roads - a world first.
It would mean that all the waste residue toner - up to 30 tonnes of it each year - can be recycled instead of ending up in the landfill.
Downer, in conjunction with Croxley and Ricoh New Zealand, has just been granted $45,800 from the Ministry for the Environment's waste minimisation fund to continue the testing of waste toner in polymer modified bitumen (PMB) and asphalt.
The testing will take place at Downer's newly-upgraded bitumen storage and blending facility in Totara St near the port.
The company, a pioneer in developing the country's roading network, installed Danish-made emulsion and PMB plants two months ago to add a new dimension to road construction in the county.
John Vercoe, Downer's technical manager of bitumen supply, said: "We have done the lab work and we can put all the toner through the plant.
"We can get 3 per cent toner in our polymer without affecting its properties, and we can put 1 per cent into the straight bitumen," he said. "It doesn't enhance our product but it doesn't detract from it, either.
"We can become a recycling plant for 100 per cent of New Zealand's waste toner, reducing the impact on the environment. It produces a saving for Croxley and Ricoh, and it's not an inconvenience for us. It's a win-win situation for everyone."
Mr Vercoe, a polymer chemist, said the project began following a research paper from United States that talked about adding waste toner to asphalt.
"Our own laboratory work was unable to reproduce the US procedure and we investigated adding waste toner to PMB. It fits well and we are the first to do it. Our research is completed and we are ready to run the waste toner in the plant to verify the results from the lab," he said.
The first trial will be conducted within two weeks. Downer would take delivery of 200 litre drums of the waste toner - which is not exactly the cleanest product - and its only hurdle now is to figure out how best to handle the fine powder.
It's dusty and the waste toner needs to be transferred to the mixer and milled with the bitumen and SBS polymer, which is imported from Korea and other parts of the world.
The cartridge waste toner would end up being part of the stronger and longer lasting polymer modified bitumen (PMB) which lengthens the life of a road surface at least five times.
Most of the country's roading network is made from the cheaper chip seal where the bitumen is sprayed first and the chip aggregate is added.
City streets are laid with the less noisy and smoother asphalt where the aggregate and bitumen is mixed and then laid by a paving machine and rolled.
The PMB, more resistant to wear and tear, is now being used on sections of highways that have particularly heavy use.
Downer has applied it on the recent upgrades of Maunganui Rd near the flyover and on the intersection of Fraser St and 15th Avenue in Tauranga, and it is popular for paving at the heavily-used ports, distribution centres and rail and log yards.
"Every time a truck goes past, the road flexes. When it keeps flexing, the road eventually cracks," Mr Vercoe explained. "During a hot summer, the bitumen softens and starts flowing away from the wheels and creates ruts.
"Adding polymer, which has a lot more flexure, to the bitumen makes the road surface stronger and gives it extra life. There's some polymer in the waste toner and that's where the project comes in," Mr Vercoe said.
So, wouldn't it be wiser to construct smoother, longer lasting road (asphalt) surfaces right from the start?
"It's hard to know," said Mr Vercoe. "The roading network is structured on low capital outlay and higher maintenance. The full life costings are very difficult to calculate.
"New Zealand, Australia and South Africa uses chip seal because of the big distances to cover with low population levels, and they are trying to stretch the roading dollar further than anyone else," he said.
As well as recycling waste toner, Downer has found a way to reduce the bitumen heat, making energy savings and improving safety.
The bitumen is mixed with water containing chemicals and churned in the emulsion plant, reducing the heat from 180C to 80C when it is sprayed on the road.
Downer has installed three emulsion plants at three of its sites in Bluff, Lyttelton and Tauranga.
"This is the future," said Mr Vercoe. "When you are spraying bitumen at 170/189C , it can cause major burns. The emulsion technique drops the temperature to a safe level."
Downer, which started in 1870 as the Public Works Department, now employs 5000 people in 50 towns and cities across New Zealand. The group also operates in Australia and through Asia, particularly Singapore, India and China.