A new type of reinforced concrete that doesn’t need any maintenance

The bridge over Cowies Creek at Deppeler Park will be made from sustainable concrete with carbon and glass fibre reinforcement that should ensure the bridge requires no maintenance over its 100 year life-span.

Deakin researchers Dr Mahbube Subhani and Dr Kazem Ghabraie designed the bridge for North-Geelong based engineering firm Austeng when Austeng won a tender to build two pedestrian bridges from the City of Greater Geelong (COGG).

Dr Subhani said the new design would avoid the usual problem of corrosion that occurs in conventional steel reinforced concrete construction.

“We have replaced the steel reinforcing bar normally used in steel reinforced concrete with more durable carbon and glass fibre reinforced polymer,” Dr Subhani said.

“Structures made with steel reinforced concrete require maintenance about every five years and major maintenance or rehabilitation every 20 years.

“This bridge should not require any maintenance for the whole of its design life,” Dr Subhani said.

Carbon and glass fibre reinforced polymer is stronger than steel and five times lighter than reinforced steel.

It also needs much less energy to make – just 25 per cent of the energy required to produce steel.

“The geopolymer concrete used in the bridge construction is also environmentally sustainable,” Dr Subhani said.

“Instead of cement, the concrete has been made using fly ash, a by-product of coal combustion.

“Cement is responsible for seven per cent of the world’s total CO₂ emissions so this structural element has the potential to cut down the maintenance cost as well as reduce CO₂ emissions.”

The beam was cast by geopolymer concrete manufacturer, Rocla, and pre-testing has already shown the bridge can successfully carry the design load.

COGG maintains about 160 recreational bridges and that number is growing through subdivision development.

Dr Subhani and his design team hope that their environmentally sustainable maintenance-free bridge is a potential candidate for new and replacement bridges throughout the city.

Learn more: Deakin researchers design maintenance-free bridge for Geelong park