Hollow Core Slabs
Hollow core slabs are floor and wall elements made from pre-stressed concrete with cores in the longitudinal axes. The cores reduce the weight of the floor element significantly in comparison with the solid slab elements. The panels can be manufactured loosely reinforced or pre-stressed. The elements are delivered made-to-measure and the required slots can be provided ex works.
In the construction industry nowadays, the principal properties are energy and cost efficiency, as well as sustainable technologies. Pre-stressed concrete elements satisfy all these criteria and therefore make a significant contribution, when the issue is future-oriented construction.
Advantages of hollow core slabs
Efficient
Optimum material consumption and low tare weight
One advantage of precast pre-stressed hollow core floors as compared to other types of floor structures, is the efficient use of material. Precast pre-stressed hollow core floors require high-grade concrete and steel. Therefore the same load rating is achieved as with cast-in-situ concrete ceilings, but with reduced use of material. In comparison with ceilings constructed in the cast-in-situ concrete method, this process saves a considerable quantity of concrete. The pre-stressing also reduces steel consumption. Pre-stressed concrete elements can span large distances with supports.
Sustainable
Concrete Core Cooling
Concrete plays an important role in reducing energy consumption for heating and cooling, principally due to its ability to store and subsequently release warmth and cold. Elements with concrete core cooling facilitate the storage of thermal energy. Pipe systems are integrated at the concreting stage.
Fast
Speedy Construction Progress
In the past, delays in construction were accepted as a consequence of the slow, conventional massive construction methods. Nowadays, the requirement for fast return on investment is of ever-increasing importance. Precast pre-stressed hollow core floors make possible a significantly shorter construction period.
Safe
Fire resistant and earthquake-proof
By means of slipformer technology precast pre-stressed hollow core floors can be equipped with shear nibs at the lateral edges, in order to increase resistance to seismic motions.
Simple
Safe, convenient working conditions
Production plants for the precast concrete industry offer a safe, healthy work environment at comfortable temperatures. This type of manufacture is based on strictly supervised industrial procedures. Therefore, potential sources of pollution by noise, dust and hazardous substances can be identified and corrected without problems. In addition, the production of pre-stressed concrete products leads to a considerable saving in staffing.
Versatile
Wide range of operational areas
Operational areas for hollow core slab are non-load-bearing walls in residential, administrative, commercial and industrial construction and perimeter walls. They are suitable as storey ceilings in all possible types of building and for infrastructure procedures.
Machines for production
Slipformer S-Liner®
Extruder X-Liner®
Can a hollow core slab also be used as a wall panel?
Hollow core slabs can be used vertically as wall panels in certain applications. While they are primarily designed for floors and roofs, their load-bearing capacity and thermal/acoustic performance also make them suitable for external or internal walls.
However, specialized precast wall panels are often preferred, since they are optimized for vertical loads, insulation, and connections. The choice depends on the project requirements and design specifications.
When using hollow core slabs as wall panels, a different side form will be applied. This side form has a male and female groove side for interlocking purposes.
Can hollow core slabs also be used in Seismic regions?
In seismic regions, hollowcore slabs are used as floor systems that act as diaphragms to transfer earthquake forces to shear walls or frames.
To perform safely, they require reinforced concrete topping and well-detailed connections (such as grouted joints or dowels) to ensure shear transfer, prevent separation, and maintain structural integrity during seismic movement.
What is the installation process of a Hollow Core slab?
As in every construction procedure, site inspection is the very first step in installing a hollow core slab.
The heavy-weighed hollow core slabs are then lifted using lifting loops to place them on the bearing surface. Careful measures are taken to ensure that adjacent slabs are positioned together for load distribution and structural integrity.
Then the grout is used to fill the joints between the slabs. Filled-in grout is left aside for good settlement. Finally, a thorough inspection is carried out to ensure that the connections and alignments are secure.
Is a hollow core slab an ecological product?
Concrete has properties that at the outset are ecologically advantageous. Concrete is durable, and requires no toxic preservatives in order to prevent its deterioration.
In industrialized countries corrosion of steel is costing about 4% of the gross national product, and half of the annual steel production in the world is used to replace corroded structures. In addition, the energy consumption of concrete is extremely low, compared to other construction materials.
How much material savings do we have using hollow core floors compared to traditional floors?
Hollow core slabs score better than other types of floors, because of the rational use of the materials.
The presence of longitudinal voids in the cross-section leads to about 45% saving in concrete compared with a plain cast in-situ reinforced slab, and at the same time cuts the amount of prestressing steel by 30% because of the lower self-weight.
For an average apartment this means savings of 14,4 tons of concrete and 275 kg steel, which certainly is a large step towards sustainability.
Comparison of the environmental effects between a precast prestressed hollow core floor and a plain cast in-situ reinforced floor for single family housing over a period of 50 years
The results show that the hollow core floor scores much better than the in-situ floor, on most environmental parameters:
• 28% less primary energy consumption
• 40 to 50% less raw material
• 37,8% less generation of waste