In recent years, asphalt sustainability is becoming a preference for end users rather than an optional value-add.
By substituting waste products from other industries, the sector can lower its carbon footprint, and in some cases, improve asphalt durability. The broader environmental benefits are reducing natural resource extraction and greenhouse gas emissions, while assisting stakeholders to meet their net-zero-emission targets.
Moreover, the latest plant technology is saving on both costs and greenhouse gas emissions through reductions in energy consumption.
Having worked in the asphalt industry since 1987, it’s a paradigm shift that Darryl Byrne, who runs Citywide’s joint venture (JV) with Fulton Hogan, remains at the forefront of.
Mr. Byrne explains that while old products still form the basis of asphalt manufacturing and laying, new innovations are gaining prominence in a range of areas, including sustainable plant technology.
“If you go back 20-25 years, we were seen as a dirty industry. You talk to people about asphalt plants and the first picture that comes into their head is some dirty industrialised facility that has a lot of smoke coming out of its chimneys, whereas in fact, we’re a very clean production business nowadays and the ‘smoke’ is actually steam,” Mr. Byrne says.
Citywide’s partnership with Fulton Hogan dates back to the beginning of 2016, when Citywide decided to enter into a JV. It conducted expressions of interest, with Fulton Hogan making an offer to secure a 50 per cent stake in the business.
Citywide opened its first plant in North Melbourne in 2007.
In 2020, it expanded its operations with a new state-of-the-art sustainable asphalt plant at Laverton North. The plant is Citywide’s second and officially opened its doors in February.
There are multiple reasons why the business case for Laverton North makes sense for the two companies – reducing a reliance on virgin resources and leveraging best practise research and development are just a few. The site also works to provide a consistent product that meets the rigorous demands of city roads and pavements through its NATA-qualified lab on site.
Citywide’s strategic positioning of its sites means it can service markets across Melbourne. Its North Melbourne site is located just a stone’s throw away from the Melbourne CBD.
“You don’t find that anywhere, so it allows us to reach not only the Tier 1 market, but also the Tier 2 and Tier 3 small contractors,” Mr. Byrne says.
“With public services and municipal works happening around the clock in Melbourne, it makes good business sense.”
As an asphalt production business, Citywide’s Laverton North Asphalt Plant services the broader road construction market, including civil infrastructure companies, councils and contractors. This comprises anywhere from a VicRoads road upgrade right through to a subdivision or small maintenance contract. The site broadly caters to asphalt for major roads, suburban streets, car parks, subdivisions, footpaths, driveways or repair and patching.
Recently, the City of Melbourne – which is aiming for net-zero-emissions by 2020 and has consistently demonstrated a desire for sustainable asphalt – laid five prominent city streets with the material in late 2019. It used asphalt made from recycled plastic at the Citywide North Melbourne Asphalt Plant.
Mr. Byrne says that being in a JV allows Citywide to leverage Fulton Hogan’s extensive research and development capabilities. Being on a shared site with Fulton Hogan also allows it to have access to a polymer-modified blending facility.
Mr. Byrne, who is General Manager for the JV, took Roads & Infrastructure on a tour of Citywide’s new sustainable asphalt plant at Laverton North.
“We have to play our part and this is where our new asphalt plants really fit into that piece of a puzzle,” he says.
“This new asphalt plant will reduce its energy consumption by at least five
With the plant up and running, Citywide will also take advantage of the Melbourne Renewable Energy Project – a local government-led collaboration driving investment in renewable energy. This will see the site powered by 100 per cent renewable energy within the next six to 12 months.
“We will be the first asphalt plant or asphalt producer in Australia to be powered up by 100 per cent renewable energy,” Mr. Byrne says.
Citywide’s new plant is using the Marini Asphalt Plant, a batch plant capable of processing up to 200 tonnes of materials per hour.
The plants support the use of VicRoads-approved mix designs, hot, warm and cold mix asphalt, dense graded, stone mastic and open graded asphalts, polymer modified asphalt and reclaimed asphalt pavement (RAP).
Mr. Byrne says the Marini was chosen after an extensive study carried out by Fulton Hogan. It examined the emissions produced by various asphalt plants and balanced it against a cost-benefit analysis looking at size and scope.
With one of the common enemies of productivity being moisture, Citywide spent extensive time establishing purpose-built bunkers on site to store the raw materials.
“All the raw materials in the bunker and in the cold feed bins that supply the plant are fully covered so we’ve put a lot of work into keeping the moisture out,” Mr. Byrne says.
“We’ve got six finished asphalt silos on this plant which can store asphalt for up to 48 hours, so it gives us plenty of flexibility with the six silos to make a large number of products to service our clients.”
He says some of the standout features include a low-emissions burner with energy retained in the plant and a foamed bitumen option.
In meeting Citywide’s clean and green ethos, the plant incorporates the company’s low-emissions asphalt GreenPave. GreenPave is an advanced warm asphalt mix and a climate sensitive alternative to traditional hot mix. It uses foamed bitumen, high RAP percentages and binder and is produced at significantly lower temperatures. The combined application of binders results in bitumen with the same performance as standard hot mix.
GreenPave is also subject to less oxidative hardening of the binder when compared to hot mix, leading to better fatigue performance over time. Additionally, it can be paved in thicker layers than regular hot mix asphalt offering greater productivity, operational savings and a swift return to traffic.
“We’ll be looking to have a full suite of products to take to the market that will have at least 50 per cent recycled content,” Mr. Byrne says.
“With the advent of the newer product we’ve developed a trademarked branding GreenPave Plas – our GreenPave with plastic additive. That particular product has a recycled content of greater than 50 per cent.”
He says that GreenPave Plas incorporates plastic, RAP and slag aggregates produced on an adjoining site at Laverton, preventing the material from going to landfill. Mr. Byrne says the slag is a good product and has high skid properties suited to high-speed road networks.
The Marini allows Citywide to increase its RAP content by up to 60 per cent through a bolt-on module, with a larger pugmill maintaining 200 tonnes an hour even with high recycled content.
As for what the future holds? While he remains busy mixing and matching the new plant to suit Citywide customer needs, Mr. Byrne says there is a wealth of opportunity to explore new business opportunities.
“We have to ensure if we’re going to develop a product that it stands the test of time. There’s no point developing a new type of asphalt and then find out that it’s got a serviceable life of five years,” he says.
“We’ve got to make sure we’re maintaining the life of our pavements, equal to today, if not superior, and this is where I think some of these high-spec perpetual type pavements do hold their own.”