New reinforced concrete uses no steel or cement

Construction company Skanska is using a new type of reinforced concrete, free of steel or cement.

A trial of the new concrete was started in December 2021 as part of the M42 road Junction 6 project near Bickenhill, West Midlands. Building materials company Tarmac supported the trail by providing two different varieties of concrete, and these were used to make a temporary haul road. The concrete used conventional materials with an alkali activated cementitious material (AACM) replacing the cement. Instead of reinforced steel, the concrete used basalt fibre reinforced polymer rebar.

The advantage of using AACM is that it lowers the carbon footprint of the concrete by about 80% compared to standard concrete. The polymer rebar is five times as strong as steel rebar, is much lighter and does not rust or corrode. Also, the polymer does not emit sparks during the cutting process, so requires no hot works permit.

During the trial, construction vehicles continued to use the road. The trial data provided insights into the benefits of producing and using cement- and steel-free concrete. The success of the trial has led to Skanska and National Highways agreeing to try the concrete out on a permanent road.

Glennan Blackmore, the highways director of Skanska, said:

“By using a unique combination of materials, we are working to not only cut carbon but also improve the structural performance of reinforced concrete, delivering better productivity, safety and cost outcomes.”

Skanska is looking at ways to use the new concrete in other projects, including HS2 tunnels, and it may find its way into concrete flooring in the future.