| PROJECTS |
Hollow-core slabs used for
CHEMICAL STORAGE FACILITY Hollow-core slabs manufactured and supplied by CM A member Port land Hol lowcore have been used for t he construction of first-f loor decking in a new 3 800m² warehouse for Caprichem, a manufacturer and distributor of a wide range of chemical-based products to more than a dozen market sectors. Completed in January 2021, the property was designed and project-managed by Structural Survey, which also supplied all the steel used for the project, including insitu columns, steel beams, the roof structure and a steel framework for outdoor shelving, the latter being constructed with hollowcore slabs as well. Just over 8m long and 200mm thick, and covering a floor area of 1 900m², the slabs were installed by mobile crane at a rate of 220-240m² per day. “Normally our installation rate’s a lot faster, but in this instance, the building’s roof – which was integral to the stability of the entire structure – had already been installed, which meant our headroom was limited,” says Petrus Theart, divisional manager of Portland Hollowcore. The slabs span load-bearing walls and steel beams, the latter being supported by the reinforced concrete columns. Each slab was cast with two 50cm exposed core cavities. Y16 rebar was inserted into the cavities of opposing slabs and sealed with concrete.
(Above): The partially completed fi rst floor showing the open cores prior to filling. (Left): Part of the soffit side of the hollow-core fi rst floor and the hollow-core shelving and walling.
“This gave the entire structure additional strength and rigidity,” says Structural Survey owner Hendri Barnard. A reinforced, power-floated concrete screed was thrown once all the slabs had been installed. The outdoor shelving was constructed with Portland’s 5m slabs. In
addition, 300m² of twin-decked shelving was mounted adjacent to two hollow-core boundary walls, each just over 30m long and 6m high. The walls were erected with 48 6m² of 5m slabs sandwiched in five layers between steel H-beams, while the shelving panels were mounted on a steel frame attached to the beams. The wall slabs were cast with a tongueand-groove system so that they could slot into each other without the need for adhesive. However, once a slab was installed, the gaps between the slab and the H-beams at either end were grouted to prevent panel movement. Barnard believes approximately six weeks were saved by using hollow-core slabs. “Being a warehouse, the floor-toceiling height of the ground-floor section was over 5m, which would have made the installation of scaffolding for in-situ construction impractical, as well as timeconsuming,” he says.
“Just over 8m long and 200mm thick, and covering a floor area of 1 900m², the slabs were installed by mobile crane at a rate of 220-240m² per day.” PRECAST | ISSUE THREE | 2021
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