PROJECT INFORMATION
• Company entering: CoreSlab • Client: Venetia Mine • Main Contractor: BMH Africa • Architect: CSKO • Subcontractor: Coreslab
VENETIA MINE RESIDENTIAL DEVELOPMENT
D e Beers’ Venetia Mine’s mine accommodation projects are being fast tracked using hollow-core slabs to construct suspended slabs. Coreslab has helped Woodtec Construction, principal contractor, and BMH, project manager, deliver more than 100 residential units for De Beers’ Venetia Mine. Last year, Woodtec Construction, BMH and Coreslab completed 33 apartments and 12 houses in Musina in record time. On the more recent mine accommodation projects, Woodtec Construction and BHM were again working to a very tight schedule. The use of hollow-core slabs ensured swift and efficient construction of the units. Hollow-core slabs provide a faster method of constructing a quality suspended slab. Hollow-core slabs are reinforced or pre-stressed concrete slabs, comprising cores that extend the full length of the elements. They generally vary in thickness from 150 mm to 300 mm and span up to 14 m, depending upon loading, and are between 300 mm and 1 200 mm wide. These precast-concrete elements are placed on a 5 mm to 20 mm-thick levelling screed on masonry walls with a minimum bearing of 100 mm. To accommodate thermal movement on roofs or exposed balconies, bitumised soft-board or other similar materials are used. This makes allowance for changes in camber or deflection, particularly where light parapet walls are built on pre-stressed hollow- core slabs. Light mesh reinforcement is also placed in the finishing screed or topping in these circumstances. Hollow-core slabs are significantly lighter than a large solid concrete suspended slab of equal thickness or strength due to the use of fewer raw materials. This reduces the cost of manufacture and transportation of the “planks” to site where they are lifted and placed, levelled and grouted to complete the suspended slab. However, one of the biggest advantages of
hollow-core slabs is that they are manufactured in a controlled factory environment where the non-modular sections are also cut to size according to the building dimensions immediately after the concrete has reached the required strength. The various elements are then transported to site where they are lifted directly from truck and placed on top of the load-bearing walls using a mobile crane or truck-mounted boom crane. Once they have been installed, building contractors and trades are able to work on the structure almost immediately to significantly accelerate the building project. This includes above and below where there is no propping or staging. The building contractor also does not have to first wait for the concrete slab to cure to proceed. Coreslab can install an element every five minutes to complete a floor structure in record time. This speed is also facilitated using special lifting tackle that has been engineered by the company. The growing popularity of hollow-core slabs in this market is largely being driven by the severe workload in a very competitive and volatile industry. These factors are being exacerbated by widespread skills shortages in the construction sector. Home builders and their professional teams want peace of mind that the installation will be done correctly the first-time round, while smaller architectural and structural-engineering firms are also increasingly specifying hollow-core slabs in the early design stages of the project to mitigate risk and reduce construction costs. High levels of accuracy also minimise wastage, another notable benefit of hollow-core slabs that is complemented by the significant cost-savings in concrete, propping and labour that is associated with the use of both in-situ construction methods and rib- and-block systems.
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21 st Best Project Awards 2022
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