Making Asphalt More Environmentally Sustainable
Q: What can be made with the equivalent of 800 plastic bags, 252 glass bottles, 18 used printer toner cartridges and 300kg of recycled asphalt?
A: A tonne of Plastiphalt – one of the latest innovations in environmentally sustainable civil construction materials in Australia.
In civil engineering and construction, asphalt has been the most environmentally sustainable paving material thanks to its recyclability. As asphalt pavements are 100% recyclable, Kypreos Group is committed to utilising this RAP (reclaimed asphalt pavement) in asphalt mix designs. Now, asphalt is being combined with recycled glass and soft plastics to make tougher and even eco-friendlier roads, driveways, highways and, soon, airport runways.
In August 2018, the first ever “rubbish” road in Australia, Rayfield Avenue, was constructed with Plastiphalt in a northern suburb in Melbourne. Hume City’s mayor Geoff Porter said the amount of rubbish going into this 300-metre stretch of road was comparable to what could be collected in Rayfield Avenue residents’ recycle bins over a 10-year period.
A few months later, in October 2018, ACT Minister for Roads announced the start of the state’s annual resurfacing program for 2018-2019, which will include the trial of Plastiphalt on existing sections of Horse Park Drive and Gundaroo Drive.
Normally, asphalt production involves mixing an aggregate (crushed stone and sand) with bitumen, a by-product of crude oil distillation which acts as a liquid binder holding the asphalt together. The connection to plastic lies in that both bitumen and plastic are polymers, whose long strands of strongly bound together molecules give them the strength and longevity required in road construction. So instead of producing more bitumen, manufacturers can add soft plastic to the mixture, which helps prevent billions of plastic bags and glass bottles from ending up in already gigantic landfills.
What’s more: in Plastiphalt, the plastic is completely melted into the bitumen like sugar in hot coffee, leaving behind no traces of microbeads that are detrimental to marine life when dumped into bodies of water. The one caveat upon its first introductions was its infancy – only time could tell whether this environmentally sustainable material is also structurally sustainable. On the other hand, this type of asphalt is cost competitive, and improvements have been made to fatigue life, giving road surfaces more longevity and capability to handle heavy traffic.
Before the addition of waste and recyclables to asphalt, companies like Kypreos Group had already been endeavouring to utilise warm-mix asphalt (WMA) technologies to reduce carbon footprints. The lower temperatures required for WMA production and placement compared to traditional hot-mix asphalt means a reduction in both energy consumption and greenhouse gas emissions.
These environmentally conscious attempts are not limited to Australia. In fact, since 2002, at least 16,000 km of road in India has been paved using asphalt made with bitumen-modified plastic, thanks to the ingenuity of Dr Vasudesan, dean and professor of chemistry at the Thiagarajar College of Engineering. The very first 20-metre prototype of plastic-modified bitumen road within his campus is still going strong after almost twenty years.
In New Zealand last year, a large-scale trial of plastic-incorporated asphalt was conducted at Christchurch International Airport. 3100 four-litre plastic oil containers went into the 250 tonnes of asphalt laid in half of the airport’s fire station. The mix was specially designed to handle heavy to extreme vehicle traffic loading typical of ports and airport projects.
Joining these major efforts in waste reduction, Kypreos Group is devoted to monitoring our ecological impact and our environmental footprints, through the implementation of eco-friendly technologies and pollution prevention. We are taking strides to build the roads of tomorrow, sustainably.