Road Science and EnviroNZ solving waste problem

06/06/2019

In 2018 China officially closed its borders to the acceptance of other countries' waste plastic. This has created a serious problem for New Zealand as plastic is being stockpiled with very few ways of repurposing it.

Downer and New Plymouth District Council worked together to address the growing waste plastic problem. The local authority had an existing partnership with EnviroNZ and together engaged Downer’s Road Science team to come up with a ground-breaking solution - Plas Mix.

Plas Mix is, in essence, raw shredded plastic that goes into asphalt. Downer’s Road Science laboratories have gone to great effort to identify the optimum plastic mix and the actual size needed for a successful product. It is then laid and paved in the same way a traditional asphalt.

The outcome means successfully repurposing waste plastic while not compromising the integrity of the pavement solutions. Downer’s Murray Robertson says partnerships are a great way to showcase sustainable solutions for the future. “The creation of Plas Mix is a collaboration between two commercial companies actively working together to solve significant local and global waste minimisation issues. The team are tasked with developing a meaningful outcome that can successfully repurpose waste plastic while not compromising the integrity of the pavement solutions.”

“Main benefits of using recycled plastic in roading is that it prevents waste going to landfill. It also eliminates the need to transport and ship these materials thousands of kilometres overseas for processing, which significantly reduces our carbon footprint,” said Glen Jones, the commercial manager at EnviroNZ.

A secondary benefit found in testing was that the performance of asphaltic road surfacing was actually enhanced by adding the plastic, especially in the areas of waterproofing and rutting.

Downer was recently awarded a 10-year New Plymouth District Council Term Maintenance contract, covering urban and rural roads in the district and includes road maintenance, CBD cleaning and water and wastewater reticulation renewals, as well as small to medium bridge maintenance.

With a unique focus on sustainability for the community and a clear commitment to safety, this contract presented the right opportunity for the first large scale trial of Plas Mix, which was delivered last month in New Plymouth. This was the first example in New Zealand, where plastic has been used to surface a public road.

The trial consumed 500 kilograms of hard plastic waste in 100 m² of road. This is equivalent plastic waste to what 1,300 people would generate in one week.

The common types of hard plastics included containers for margarine, yogurt, cottage cheese, butter, and bottles for cleaning products such as Jif, dishwasher powder bottles, polystyrene packing, and coloured juice bottles.

Downer is committed to world-leading insights for customers said Mr Robertson. “Downer and the Road Science team are committed to providing innovative solutions for New Zealand’s roading market. Developing practical and cost effective solutions to sustainability challenges remains front and centre for our team. Reducing solid waste from entering landfills, while reducing our carbon footprint and providing high quality cost effective outcomes is a challenging yet motivating assignment for us.”   

About Downer in New Zealand

Downer has been designing, building and sustaining New Zealand’s infrastructure for over a century and is a leading provider of integrated services in Australia and New Zealand. With over 12,000 employees in New Zealand, we work alongside some of New Zealand’s biggest businesses, councils and government agencies.

Safety and community are at the heart of our business and we aim to employ the best people and bring thought leadership to each stage of the asset lifecycle.

Through our family of brands, we can design, build and maintain a city. The Downer family also includes Hawkins for non-residential building projects, Spotless for Integrated Facilities Services, Road Science, developing innovative road and pavement technologies and Taylors Laundries.

About Road Science

Road Science is New Zealand’s leading designer and supplier of bitumen and bitumen-based products with four IANZ accredited testing laboratories and four bitumen plants through-out the country. Road Science promotes change through harnessing creative potential to deliver new and innovative solutions to the pavements industry.