Post-tensioned flat slabs for building construction
The principle of post-tensioned concrete is used for post-tensioned flat slabs. The term post-tensioned concrete is used when a compressive stress is applied to the concrete through the use of prestressing steel. This technology can be used in almost all types of buildings and offers many advantages.
Post-tensioned flat slabs in a nutshell
Post-tensioned flat slabs are slabs made of post-tensioned concrete.
By using tendons, compressive stresses are applied to the concrete. This so-called post-tensioning ensures that no or only low tensile stresses occur in the concrete, which concrete can generally only absorb to a small extent. As a result, the mild reinforcement usually used to absorb the tensile stresses can be significantly reduced. At the same time, spans can be increased and slab thickness reduced. For post-tensioningprestressing, a distinction is made between unbonded and bonded post-tensioning.
4 Key Benefits
Post-tensioned concrete allows a significant increase in spans and leads to a reduction of columns compared to conventional reinforced concrete. Furthermore, the use of post-tensioned flat slabs allows improved aesthetic and economic design options through greater design flexibility.
Conventionally reinforced slabs can lead to restrictions in the use of the building, if for example columns have to be used at intervals of a few meters in order to be able to transfer the loads and comply with the permissible slab deflections. Important usable space is thus lost.
Quality and durability
The use of post-tensioned flat slabs can eliminate construction joints. On the one hand, this is a very welcome effect for floor slabs that are driven on (e.g. forklift trucks). On the other hand, the reduction of joints as well as the controlled slab deflection lead to improved durability of the slabs and thereby lower maintenance costs. Even with high loads, a crack-free construction can be guaranteed.
In addition, post-tensioned flat slabs represent a more sustainable solution compared to conventionally reinforced slabs. The reduction in slab thickness results in material savings, in particular concrete and thus cement is saved, which leads to a reduction of CO2 emissions. The savings in mild reinforcement mean that, despite the additional prestressing steel, less steel is required overall than in a solution without post-tensioning. The material reductions, which are continued in other sections such as the facade, also allow for transports to be reduced - another plus point in terms of sustainability.
Cost efficiency and time savings
The use of post-tensioned flat slabs accelerates construction cycles. Specifically, post-tensioning, which is possible even at low concrete strength, allows early stripping of the slabs. This saves time and costs. The savings in concrete and reinforcement lead to lower material costs. These material savings in turn lead to weight savings and in the end to benefits for the foundation of the structure. The foundation dimensions and thus also the size of the excavation pit can be reduced.
The reduction in slab thickness leads to a lower overall height of the building and thus less facade area and costs or, alternatively, in the case of high-rise buildings for example to an additional floor. Accordingly, a construction with post-tensioned flat slabs offers an efficient and economical solution for various building construction projects.
Parking of the Valais Hospital in Sion, Switzerland
The project, developed by the award-winning architects in 2017 - 2018, was implemented by the general contractor Implenia. Thanks to the crossbeam system, consisting of a slab resting on three free supports, it was possible to increase the traffic and parking areas.
For me, it becomes exciting when we not only facilitate cost savings and acceleration with the post-tensioning of slabs, but also promote sustainability at the same time.
Armin Steinmetz, Division Manager Flat Slabs, BBV Systems
BBV Systems - From planning to installation
BBV Systems' post-tensioned flat slabs offer a cost-efficient and sustainable solution for demanding building construction projects. BBV Systems provides support from planning to installation and develops, among other things, detailed solutions for post-tensioning. Early involvement of BBV Systems is recommended so that planned construction projects can fully benefit from the numerous advantages of post-tensioned flat slabs. Later involvement is also possible, in which case BBV Systems will investigate re-design options.
Would you like to find out whether your project is suitable for post-tensioned flat slabs?
If you would like to benefit from the advantages of post-tensioned flat slabs, please contact us as soon as possible or even before the project is planned. Get in touch with Armin Steinmetz.