BUILDING: Demolished Cooling Towers Resurrected
Recent Western Cape Business News
The cooling towers of Cape Town’s old Athlone Power Station, which were imploded last year, have made a substantial contribution to reducing the carbon footprint of a concrete masonry and paving block manufacturer in the heart of the city.
The company is Concrete Manufacturers Association (CMA) member, Cape Brick, which has been sourcing up to 75% of its raw material from demolished buildings and other structures with a high percentage of concrete for the past 11 years.
The Athlone cooling towers yielded roughly 16 000m³ of rubble, equivalent to 20 000 tons of concrete, which provided Cape Brick with enough raw material to last them approximately four months.
CMA director, Hamish Laing, comments that considerably less embodied energy is required to produce concrete masonry units using recycled concrete than using freshly quarried sand and stone aggregates.
“Embodied energy is defined as the energy consumed in the manufacture and transportation of construction materials. It is measured in megajoules per kilogram (MJ/kg),” says Laing.
The use of recycled material does not mean that product quality suffers as its properties are equivalent
to quarried materials. It offers comparative compressive strengths and is a truly green material which is itself fully recyclable.
Laing says direct environmental benefits of green masonry are:
Fewer virgin aggregates have to be quarried, reducing the impact on the environment.
Reduced transport costs as most quarries and are located far from their markets.
Construction and demolition rubble is normally dumped, so using it as a raw material source eases the pressure on landfill sites.
Most landfill sites are located far from the demolition site, so using these materials further reduces transport costs.
Cape Brick’s own waste material is reprocessed and therefore does not have to be dumped, easing pressure on landfill.
Cape Brick managing director, Anthony Gracie, says it takes approximately half a megajoule to produce a kilogram of masonry or paving block using recycled material, whereas close on a full megajoule, i.e. twice as much energy, is typically required to produce the same product using original material.
“In other words our 190 masonry block, which weighs 16kg, has an embodied energy of 8MJ, whereas a conventional block of the same weight, but manufactured with original materials, has an embodied energy of 15.04MJ. This energy usage can be further extrapolated into kilowatt hours (Kw/h) per brick, which in the case of Cape Brick’s 190 block is 2.22Kw/h. The rating for an equivalent conventional block is 4.17Kw/h."
Business News Sector Tags:
Fax 2 Email
Study IT Online
Work from Home