Voided biaxial slab
[citation needed] Another major benefit of the system is its reduction in slab weight compared with regular solid decks.
Concrete has numerous applications in building construction, but its use for horizontal slabs is limited by its relatively high density which reduces the maximum span.
[2] The usual method of rectifying this disadvantage is to incorporate some kind of reinforcement, which enables concrete slabs to be used for a broad range of spans and loading conditions.
This creates an internal array of hollow boxes in the slab, which acts as grid of horizontal supports for the flat surface on top.
[7] This framework has been implemented in various ways, but the most efficient method uses a steel mesh in order to reduce material use and create an optimal geometric proportion between concrete, reinforcement, and voids.
[1] Prefabricated modules commonly consist of a fully cast piece of slab, including all components encased in concrete.
A contiguous layer of smooth finish concrete is then poured onsite, along with the addition of structural anchoring to fix the modules together.
To ameliorate this, the slab may be cast in multiple layers so that the mesh is initially anchored and is then able to restrain the voids from floating upwards in later pours.
[9] In 2017 the BubbleDeck system caused controversy due to the collapse of a parking garage at Eindhoven airport in the Netherlands.
[10] This was due to insufficient shear strength at the interface between the precast concrete slabs, potentially caused by high temperatures during construction.
The reduced mass of biaxial slabs also results in a more environmentally friendly product which produces less CO2 emissions both in its construction and indirectly through the reduction of surrounding structural support.
One-way decks are supported by a combination of walls and beams, leading to a relatively rigid structure which increases the risk of progressive collapse.
In some cases where greater shear resistance is required in a localised area (such as junctions with piers or walls), the voids may be omitted, leading to a partially solid slab.
