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New UBC concrete technology to shake up seismic construction

0 558 Technology

by Russell Hixson

After 15 years of hard work and research, a new earthquake resistant concrete developed in B.C. will see its first real-life application on a Vancouver elementary school seismic retrofit project.
New UBC concrete technology to shake up seismic construction

The project to develop the eco-friendly ductile cementitious composite (EDCC) was supervised by Nemy Banthia at the University of British Columbia (UBC) in Vancouver. He explained that EDCC's design goes all the way down to the molecular level where it is engineered to be strong, malleable and ductile like steel — capable of dramatically enhancing the earthquake resistance of a seismically vulnerable structure when applied as a thin coating.

The new technology comes at a time when Vancouver is in the middle of a massive seismic upgrade to its schools. Currently 165 seismic school upgrades have been completed and 14 are under construction. Twelve have proceeded to construction and 155 are in the business case development stage.

"When you are trying to push the boundary with the performance of a material you have to understand the material at many different levels, the macro, the micro and the meso," said Banthia. "It's to truly understand the fracture process at every level and what is precipitating the failure. These are mechanisms happening at almost the nano level."

He and his team worked for years to try to understand why and how cracks form and how various materials impact their formation. Their solution to this problem is a cement with polymer-based fibres, fly ash and other industrial additives that has proven itself in extreme tests.

During tests, a wall sprayed with a 10-millimetre-thick layer of EDCC was shaken at conditions comparable and exceeding the 9.1 magnitude earthquake that hit Japan in 2011.

"We scaled it up to 180 per cent of Tohoku (Japan) and could not get it to fail," said Banthia.

A wall without the EDCC failed at 60 per cent.

Not only does it perform well seismically, the material also uses as little cement as possible.

"By replacing nearly 70 per cent of cement with fly ash, an industrial byproduct, we can reduce the amount of cement used," said Banthia. "This is quite an urgent requirement as one tonne of cement production releases almost a tonne of carbon dioxide into the atmosphere and the cement industry produces close to seven per cent of global greenhouse gas emissions."

Not only does the mixture mean it is environmentally friendly, it is also cheap, simple and easy to replicate, Banthia added, which is a huge boon for countries desperate to protect themselves from earthquakes.

EDCC has been added as an official retrofit option in B.C.'s seismic retrofit program and the team will be working with contractors in the next couple of months to upgrade Dr. Annie B. Jamieson Elementary School in Vancouver.

But Banthia said the team has been overwhelmed with inquiries from more than 35 countries eager to use the material. The research was funded by the UBC-hosted Canada-India Research Centre of Excellence IC-IMPACTS, which promotes research collaboration between Canada and India.

IC-IMPACTS will make EDCC available to retrofit a school in Roorkee in Uttarakhand, a highly seismic area in northern India.

"Imagine UBC technology being applied to save lives of children in India," said Banthia. "That's our international reach. It's very gratifying. I think I am very privileged to be able to make that difference."

And he isn't done yet. Banthia said the team is already beginning the long process of experimenting with other fibres and materials to make the mixture even more eco-friendly and high performing. He also hopes to be able to use more recycled fibres to bring down the cost, as fibres are one of the most expensive ingredients.

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