Damage from a car entering a residential building. Image: David Dunning Minster FM North Yorkshire
When a car collides with a building at speed, the damage is catastrophic: the vehicle punches through the brick and mortar exterior causing structural damage to the building, and potentially injuring or killing the driver, passengers, and building occupants.
Damage from these collisions runs to almost $50M each year, based on the estimated 2,000 intrusions each year recorded in Australia.
A new building material being developed by a QUT research team can be applied to the front façade of a building, leading to less damage to the car, the vehicle’s occupants and the building itself in the event of a collision.
The emerging research is supported by a $415K Australian Research Council Discovery grant and will be tested at a world-first impact testing facility currently being built in Brisbane’s north.
More city, more problems
As our cities grow bigger and more densely populated, there are more cars on the road and more buildings constructed closer together on smaller lots.
Lead researcher Professor David Thambiratnam and his team, Professor Tommy Chan, Dr Tatheer Zahra and Dr Mohammad Asad, believe that the solution lies in auxetic materials: a synthetic substance that is combined with building mortar to create an impact-resistant building material.
“Auxetic materials have a special property called negative Poisson ratio,” explained Thambiratnam.
“Normally, if you have a block of rubber and you stretch it horizontally, it will lose height to accommodate the new width. Similarly, if you stretch it vertically it will become thinner as it becomes taller.
“Material with a negative Poisson ratio expands equidistantly in all directions as it’s stretched, because of a wider spacing between the material’s particles.”
When combined with mortar it gives a building’s surface flexibility to absorb impact and recover, as opposed to denser materials like brick, which can shatter under impact.
This auxetic composite render on the street-facing wall only needs to be 1–2cm thick, and costs about $190/m2, making it incredibly cost effective.
Read the full article here.