Today I want to make a well-deserved mention to one of the most versatile precast elements that can be done with UHPC: The slab.
UHPC slabs can provide efficient solutions in modular housing, balconies, structural flooring, industry, and civil engineering among others. Their main advantage compared to ordinary concrete slabs is that, for the same load carrying capacity, their weight and depth can be up to 70% lower, reducing production and transportation costs, resources, and environmental impacts. In these precast 2D elements rebars are generally avoided, assuming the steel fibers all the structural role to provide the necessary toughness to be safe and avoid macrocracks. Besides, the fineness of UHPC granulometry allows to achieve an excellent surface quality, facilitating that the elements play both a structural and an architectonic role. Other benefit of this highly industrialized fire-resistant solution is that the design of the connection can be adapted to the needs of the client, embedding connectors or screwing the elements.
To show the wide possibilities of UHPC slabs, the two figures represented below show the characteristic distributed live load that UHPC slabs can resist with a thickness between 25 mm and 50 mm. Two different support conditions are shown: Simply supported in two edges (first figure), and simply supported in four edges (second figure). The figures have been calculated with Formex® UHPC slabs, which prices in the market vary between 60 and 180 €/m2 depending on the thickness, the slab dimensions, the finishing and the connection system.
Simply supported in two edges
Simply supported in four edges
One may be surprised observing that a 2.5 x 2.5 m2 slab can, with only 4 cm of thickness, carry 700 kg/m2 of live load, but it is more shocking to take a look at the ratio between the load carrying capacity and the self-weight of the slab for the different thicknesses (figure below). Noticing that a 50-mm-depth slab supported on four edges can carry more than 10 times its weight, we could state that UHPC is among construction materials what ants are among insects!