Technical Information

Technical Specifications

Elematic SA’s hollow core concrete slabs are designed and manufactured with precision, using world class technology. A variety of slab thicknesses and widths are available and can be used in combinations to suit the requirements of every project.

We manufacture prestressed hollow core concrete slabs in a variety of different slab types and thicknesses. All slabs have a standard 1 hour fire rating, but higher fire ratings can be achieved if required.

Slab panel thickness	120mm	150mm	200mm	250mm
Standard width	1200mm	1200mm	1200mm	1200mm
Area of cross section	0.100482 mm²	0.099222 mm²	0.119619 mm²	0.149209 mm²
Theoretical weight of slab	215kg/mm²	220kg/mm²	270kg/m²	340kg/m²

Material properties:

Accepted bearing tolerances:

Design parameters:

Serviceability live load versus span diagrams are available for use in the project budget phase. We do recommend, however, that architectural and/or engineering drawings be forwarded to the Elematic SA design team (info@elematicsa.co.za) for a confirmed budget quotation.

Cross sections to the different available prestressed slab thicknesses are available on request.

Steel Applications

Where steel is required for structural support, Elematic SA slabs can easily be incorporated in a variety of configurations. For more information on this please contact us.

Typical steel support solutions can range from a conventional downstand support beam (beam below the hollow core slab soffit) or an upstand beam where the beam is located within the slab thickness (with only the beam bottom flange visible from below).

Design Parameters

No propping is required.
Only a 40mm levelling screed is required over the slab in most cases; however, a structural topping may be required from time to time, depending on the loads. Please check with our design department.
Mesh to be used on external areas such as walkways, balconies and staircase landings as these areas are exposed to weather conditions (expansion and contraction).
Mesh to be used internally when the screed area exceeds 16m².
Expansion joints to be utilised in tiled areas in accordance with the tile manufacturer's specifications. Elematic SA can provide further technical information upon request.
Spans of up to 11m are possible with a 250mm deep slab with a structural topping.
Cantilevers can be provided when using Elematic SA hollowcore concrete slabs.

Site Applications and Requirements

The customer must provide an area of +/- 7m of clear and level access around the building for Elematic SA to safely pack slab panels.
In order to obtain a flush ceiling on brickwork, the load bearing wall must be level. Avoid internal walls being higher. If brickwork is not level, a mortar bed will be required on top of the brickwork.
Elematic will ensure all adjoining panel V-joints are aligned and straight.
As the panels are designed and manufactured specifically for your project, site measurements need to be accurate to avoid delays.
The customer must provide, and make freely available, the sand and cement required for grouting and filling up of the joints.

Depending on the imposed load configuration on the slab panels, side-by-side precast concrete lintels can be used for openings (e.g. doors and windows) up to 1.8m wide in load-bearing brickwork supporting slab spans up to 7.0m long. The side-by-side lintels must have a minimum of five brick courses reinforced with brickforce in every course. All openings exceeding 1.8m must be referred to the ESA or project structural engineer for the design and detailing of supplemental structural steel beams.
Should a panel be required inside a building, a minimum entrance height of 4.5m high by 3.0m wide is needed, provided there is sufficient turning space for trucks.

Screeding

On contracts where hollow core slabs are used indoors and no structural topping is specified a simple 40 – 50mm levelling screed is required.

All loose material is to be removed from the tops of the slabs, which should be thoroughly wetted and screed applied immediately. The levelling screed should comprise 1:4 mix by volume of cement to clean river sand. Water should be added to the mixture to an extent that the mixture is relatively dry but remains easy to float finish.
The screed should be laid to an approximate thickness of 40 – 50mm. After laying the screed it should be steel floated and then wetted for 48 hours to prevent shrinkage cracks.

Further technical information on this procedure is available on request. We are happy to discuss your particular requirements with you.

Lighting

A variety of lighting options can be utilised with Elematic SA's prestressed hollow core concrete slabs. Further technical information on this procedure is available on request.

Fire Ratings

All our slabs come standard with a one hour fire rating, which can be increased to a two hour rating if required.

Tiling

Further technical information on this procedure is available on request.

South Africa’s leading manufacturer of precast concrete products.

Contact us for helpful and experience-backed advice about any projects you have. We are available to assist with project solutions. All compliance assessments and certifications are available on request.