Cobiax voided slab technology systems is based on generating specific hollows inside a reinforced concrete slab. Cobiax uses recycled lightweight plastic void formers to replace the heavy concrete inside a slab where it is not required. The resulting savings of up to 35% in concrete and weight has a positive effect on the construction of the slab itself (e.g. less deflection, larger spans or thinner slab thickness) and hence on the whole building structure.