Exciting concrete innovations

Self compacting concrete being discharged for Troff beams on a Tauranga bridge.

Although it has been around for centuries, concrete is continually evolving as a construction material, with some exciting new innovations entering the market.

Recent developments include Self-Compacting Concrete (SCC), a concrete that is able to flow under its own weight and completely fill formwork, while maintaining homogeneity even in the presence of congested reinforcement, and then consolidate without the need for vibrating compaction.

De-polluting concrete, which incorporates photocatalysts that help to decompose organic materials such as dirt, soot, mold and bacteria is another recent development.

“Photocatalytic concrete has environmental benefits and provides aesthetic endurance, keeping the structure looking like new,” says Rob Gaimster, chief executive of the Cement & Concrete Association of New Zealand (CCANZ).

Translucent concrete is another emerging material, which is being used to stunning effect in a variety of architectural applications. The translucent or ‘light emitting’ properties of the material are achieved by embedding fibre optics.

A microbiologist in the Netherlands has been developing ‘bio-concrete’ over the past 10 years, which uses bacteria to heal cracks in concrete as they appear. The bacteria and calcium lactate are set into capsules and added to the wet concrete mix as a ‘healing agent’.

If a crack eventually forms and water enters, the capsule opens. The bacteria then germinate, multiply and feed on the lactate, and in doing so combine the calcium with carbonate ions to form calcite (or limestone) that closes up the cracks.

“This product could be the start of a new age of biological buildings,” says Rob.

Bio-concrete, which uses bacteria to heal cracks in concrete as they appear, is an exciting new innovation.

Even ‘bendable’ concrete is now a reality. Flexus is a concrete material bonded with polyvinyl alcohol synthetic fibres to give it tensile strength. It can be sprayed onto structures and even interior walls to provide earthquake strengthening.

“Other concrete systems that continue to evolve include engineered concrete raft systems for residential foundations in seismic regions”, says Rob.

“Furthermore, Monocast is a system in which every concrete wall is poured onsite in one continuous pour.”

Compass Homes has just opened the first Monocast concrete show home in Huapai, Auckland that demonstrates this technology.

The exterior wall of the show home is fully insulated encapsulating a continuous 50mm insulation barrier, with excellent thermal benefits.

“Monocast has spent three years developing this system, and claim they will be able to build the concrete structure in five to seven days, reducing the overall house build time to eight to 10 weeks. It is another exciting innovation for the concrete industry.”

The architectural merits of concrete continue to be explored from a design perspective too, says Rob.

“Architects and designers these days really know how to get the best out of concrete. We are seeing a host of interesting buildings go up in both the residential and commercial space. The new Len Lye building in New Plymouth is a fantastic example of what can be achieved. It’s absolutely stunning.”