$970,000 road trial shows signs of failure

A RECENTLY completed road trial using a nanotechnology stabilising agent at Bald Hills is already showing signs of failure.

The $970,000 trial conducted by the City of Ballarat and contractor Fulton Hogan was meant to halve costs and help roads better withstand increased traffic and harsh weather conditions.

Although initially deemed a success, the 1.6-kilometre road reconstruction of Gillies Road between Jubilee Road and Millers Road is showing signs of failure in the base level.

“The City of Ballarat takes its responsibility in delivering safe, sustainable and cost-effective roads infrastructure extremely seriously,” City of Ballarat director of infrastructure and environment Bridget Wetherall said.

“While early indications of the trial in April showed the outcome was a success, the treated base layer is showing some signs of failure in small, isolated areas.”

City of Ballarat staff worked with Fulton Hogan and the product agent throughout the construction period and the trial was completed to exact specifications.

Retired civil engineer Michael Knowles has extensive experience using chemical stabilising agents, including for the United Nations and World Bank.

Mr Knowles said there are various types of stabilising agents, and he believes in the case of Gillies Road, the agent that was chosen was unsuitable for the soil type.

“There are a whole range of stabilisation agents, there are at least eight that I am aware of that have been documented,” he said.

“The most important thing is the testing of the soil to determine which of those agents has the best effect, that is the secret of the exercise.

“The problem is… you have agents working for these various petrochemical companies that manufacture these stabilising agents.

“What I suspect happened with Ballarat is they simply got sold by the producer of the product who said ‘oh yes I’ll show you how to use it, we’ll have such a good time’ and sadly the result has not been what was expected.”

The section of road passed testing including a proof roll, a test for bearing capacity with the use of a pavement deflector meter and compaction testing.

“We have re-engaged with geotechnical engineers and the nanotechnology supply consultant, with testing now underway in a bid to identify the cause of the deterioration,” Ms Wetherall said.

“Pending these results, we will then determine the best course of action to remedy the road.

“In the interim, defects are being patched with asphalt to ensure safety for road users.”

The nanotechnology stabilising agent is known for its ability to reduce the required pavement depth and create a bearing capacity five to 10 times stronger than a conventional road.

Traditional methods to repair the road were estimated to cost approximately $2 million.

Several small nanotechnology stabilising agent trials with promising results have been previously completed by the City of Ballarat.

Mr Knowles said he believes the the City should continue to work with stabilising agents, however, it is important to complete accurate soil testing.

“I would hate to think that the…council are just going to throw this experience in the bin,” he said.

“What they need to do is learn from it, learn the need for proper chemic matching with soil type.”

Another 4.1-kilometre stretch of Gillies Road is being reconstructed between Addington Road and Glendonald Road using standard methods.

“While this trial result is disappointing, the City of Ballarat remains committed to exploring innovation with a focus on safety, quality and long-term value for the community,” Ms Wetherall said.