Lateral restraint blocks made of an engineering plastic that typically retains most of its strength over 100 years are being produced by Hercules Engineering to safeguard suburban and highway concrete bridges against earthquakes and radical structural movement.
The custom-fabricated high density polyethylene PE 100 blocks are used as sacrificial elements so concrete components will remain preserved instead of grinding on one-another, says bridge bearing producer Mr David Booty, Manager of Hercules Engineering (a division of Cut To Size Plastics).
“Apart from minimising sliding wear, HDPE blocks can also minimise the impact of shock by deforming and absorbing the kinetic energy that could otherwise fracture or destroy single span beam bridges spanning creeks, hollows and smaller obstacles, potentially causing accidents, human casualties, disrupting vital communications and costing time and money to restore,” says Mr Booty.
An earthquake exceeding magnitude 7 occurs somewhere in Australia every 100 years or so, according to Australia’s Seismology Research Centre. Even relatively smaller earthquakes – such as the magnitude 5.6 Newcastle earthquake – can cause extensive damage.
“Bridge builders – including public works and private enterprise – are very aware of their Duty of Care to safeguard their structures’ safety so we had approaches to see what we could recommend as the best long-term, simple and cost-efficient solution. It turned out the PE100 blocks were not only the best polymer available for the job, but also one of the least expensive,” said Mr Booty, whose company produces a range of bridge bearings that are in strong demand as bridges cope with the expanded loads they have to carry on public and private roads, including those serving resource, construction and civil engineering sites.