Waterfront project goes green with ecobricks

The Ridge Building, a bespoke eco-building, will serve as the regional office of a multinational client, Deloitte.

The ecobricks comprise polyethylene terephthalate (PET) plastic bottles, including two-litre Coke and other popular soft drink bottles. They are filled to constant density with waste plastics such as chip packets, candy wrappings, shopping bags and waste generate, and were donated by community volunteers and scholars from Cape Town’s suburbs. Quality control is undertaken on site by the main contractor. The checked bottles then get used as void formers in the concrete slabs in the central toilet areas on each floor of The Ridge.

The Ridge will consume 12,000 ecobricks, each creating a void and displacing on average 2l of concrete. At an average density of concrete being 2.4 kg/litre for Portland Cement Concrete (PCC), this equates to a displacement of 57,600 kg (or 57 tonnes) of concrete in the absence of any other void forming material being used. The material, cost-saving and environmental benefit of this programme is significant.

"Often, builders incorporate void-forming materials into concrete slabs. These are of a much lower weight than concrete. They are sometimes made of expanded polystyrene (EPS). Under normal loads, these voids do not undermine the structural strength of the slab. But they offer many other benefits, which is why we use them," says Mark Noble, development director at the V&A Waterfront.

“Together with our various other established recycling programmes, which include a substantial quantity of the building waste from the Silo project being re-used, these techniques make a vital contribution to the circular economy. The is what we term ‘Our Normal’, a bold step into participating in this new economy and the environmental challenges we face”, he says.