Precast Prestressed Ribbed Slabs Using Natural Stone and Reused Concrete

Solution

In collaboration with Cooperative 2401, VSL Switzerland, and Marti Construction, we developed an approach to avoid crushing concrete by directly using natural stone or reusing existing concrete: what if we cut, assembled, and prestressed low-carbon mineral elements sourced from quarries or deconstructed buildings to create a new modular slab system?

Thanks to the Viva project of the Canton of Vaud and the Circular Economy Support Fund (SPEI), the consortium was able to develop, produce, and test four prototypes: three prestressed segmental slabs made from reclaimed concrete and one from stone. The reclaimed concrete prototypes demonstrated superior mechanical performance (stiffness) compared to new reinforced concrete, achieving over 60% reduction in the slabs’ carbon footprint. This paves the way for circular, low-carbon, and resource-efficient construction.

The stone slab, for its part, takes advantage of the material’s high compressive strength, which can reach up to 180 MPa in some granites – well beyond what is required for concrete. However, since stone is anisotropic, its performance depends on the direction of the applied loads and requires specific analysis to prevent failure modes such as delamination along sedimentation planes.