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A century without maintenance – Geelong’s everlasting bridge

Deakin engineers Mahbube Subhani and Kazem Ghabraie with Austeng Managing Director Ross George and their geopolymer building material.

The City of Greater Geelong’s 100-year maintenance-free bridge tender process is highlighting the public sector’s ability to incentivise commercial scaling through procurement.

While new billion-dollar projects dominate public attention and government budgets, more than $30 billion is required to renew and replace Australia’s existing infrastructure, according to the Australian Local Government Association’s 2018 State of the Assets report.

Additionally, the report, which draws on responses from 408 Australian councils, shows 21 per cent of timber bridges and four per cent of concrete bridges are in poor condition. As a result, the cost of bridge maintenance is a critical component of state and local government infrastructure spending.   

According to Guy Wilson-Browne, City of Greater Geelong Director City Services, the city owns and manages more than 160 bridges.

“Many of these are timber, concrete and steel pedestrian bridges, which vary in condition and require significant ongoing maintenance,” Mr. Wilson-Browne says.

“This is a significant liability, so we wanted a solution that was better than anything else currently available on the market.”

To address maintenance costs, both current and future, the City of Greater Geelong has enacted a new approach to public procurement via the Procurement for Innovation method.

Used extensively overseas, Procurement for Innovation refers to any public procurement practice intended to stimulate innovation through research and development and the market uptake of new products and services.

In practical terms, governments establish forward commitments to support the procurement of products not yet available on the market.

A state government, for example, could commit to purchasing road monitoring artificial intelligence sensors that are not yet fully released or commercially scaled. This in turn incentivises further research and development through the promise of commercial end markets.

In 2017, the City of Greater Geelong applied the Procurement for Innovation concept to a 100-year maintenance-free bridge tender.

Mr. Wilson-Browne says the tender invited companies to develop solutions to the costly maintenance problem associated with traditional bridges, which cost the city roughly $500,000 to inspect, repair, maintain and replace each year.

“The tender was the first in Australia to be offered using a Procurement for Innovation process, which aims to encourage the development and viability of clean technology, using the substantial buying power of public sector procurement,” he says.

Mr. Wilson-Browne says eight infrastructure firms expressed interest in the project, all with support from Cleantech Innovations Geelong – an industry support collaboration between the City of Greater Geelong, the Geelong Manufacturing Council and the state government.

“Cleantech is designed to support the development of economically viable products and services that harness renewable materials and energy sources through market stimulation and grants programs,” Mr. Wilson-Browne says.

“Having Cleantech involved helped bring engineers, designers and manufacturers together to work collaboratively and develop a solution for the maintenance-free, age-defying bridge.”

The contract was ultimately awarded to a consortium comprising local manufacturer Austeng, Deakin University’s Waurn Ponds Carbon Nexus facility and engineering company Rocla.

Mr. Wilson-Browne says the decision to award the consortium was based on price, innovation and the level of local involvement.

“The Austeng-led consortium researched and developed a new and innovative combination of materials, which includes geopolymer, made with partly recycled materials, reinforced with carbon fibre,” he says.

“This combination of materials resulted in a novel building product that is stronger and lasts significantly longer than any existing products.”

Mr. Wilson-Browne says the bridge, designed by Deakin University researcher’s Mahbube Subhani and Kazem Ghabraie, will require no maintenance over its 100-year lifespan.

As part of their design, Dr. Subhani and Dr. Ghabraie replaced the steel reinforcing bar normally used in concrete with a more durable carbon and glass fibre-reinforced polymer. Additionally, as an alternative to cement, the bridge’s concrete is manufactured using fly-ash from coal combustion.

While structures made with steel reinforced concrete require maintenance every five years, and major maintenance or rehabilitation every 20 years, Mr. Wilson-Browne says the use of fly-ash concrete sidesteps corrosion due to its highly alkaline composition.

In addition to structural integrity benefits, the use of fly-ash in concrete manufacturing offers a viable end-market for the waste material, which currently accounts for 18 per cent of Australia’s total waste stream.

As a by-product of combustion, Mr. Wilson-Browne says geopolymer is also an emissions-friendly alternative. He adds that cement production is responsible for approximately seven per cent of the world’s carbon dioxide emissions.

Pre-construction beam failure testing began in May 2019, with Mr. Wilson-Browne explaining that recent testing shows geopolymer carbon-reinforced beams are 15 per cent stronger than concrete.

“While the bridge is still under construction, this is very exciting news and indicates the product could be used in other civil construction projects in the future,” he says.

“Innovative programs like this help stimulate local economic activity, industry confidence and can help foster a growing number of innovative businesses in Geelong.”

After adapting the Procurement for Innovation method, Geelong become the first designated UNESCO City of Design in Australia.

The UNESCO program highlights cities that use creativity to build more sustainable and resilient communities.

Mr. Wilson-Browne says the designation presents an opportunity to showcase and celebrate the city’s industrial and commercial activities.

He says other City of Design led projects include partnering with 47 other Victorian councils to form Australia’s largest renewable energy buying group and developing the Malop Street Green Spine botanical walk.

“These types of projects are critical for showcasing what is possible in growing regional areas,” he says.

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