South Africa’s massive backlog in affordable housing is likely to see continued demand for precast hollow core concrete slabs, given the high-quality finish and the time that this technology saves in the construction process.
“With rapid urbanisation and the increased premium on land in urban areas, multi-storey residential designs are now the norm,” says Elematic SA director, Craig Webber. “This makes the use of pre-stressed concrete slabs an efficient and affordable solution.”
Webber emphasises that the precast option eliminates the need for back-propping and allows other trades to start working under the slabs immediately, significantly accelerating the project schedule.
Moreover, the high-quality finish on the soffit – or underside – of the slabs makes an additional false ceiling unnecessary and eliminates this potential cost.
Traditional vs precast
Using the traditional rib-and-block method of slab construction, contractors can wait about three weeks for concrete to cure fully, before props can be removed and work can commence.
“By comparison, we install our precast slabs on one day and grout the next, allowing building to start on the third day without any further delay in the project timeline,” he says.
As the largest producer of pre-stressed hollow core slabs in the Johannesburg area, Elematic SA’s two factories include 16 beds for a variety of slab sizes.
Helping the business sustain its quality standards is construction material leader AfriSam, which provides a reliable supply of specialised cement – the Rapid Hard product in the 52.5R strength class – to Elematic SA’s factories near Benoni. AfriSam Rapid Hard cement is very fine, giving it a larger surface area to react with water, which increases the rate of hydration and gives it higher early strength.
Different approach to managing concrete
The manufactured concrete product can be released from the mould sooner, speeding up the production cycle and making factories as efficient as possible. It also provides consistent strength performance, so that the production processes can be timed with precision and without any danger of breakage due to weakness when removing products from moulds. The high early strength makes this cement brand ideal for pre-stressed members.
Main image: In operation since 2005, Elematic SA received ISO 9001 certification in 2009 and its products are approved by the South African Bureau of Standards.
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