Site air-permeability of HPSFR and conventional concretes

Synopsis: An investigation in an industrial building devoted to manufacturing equipment for the pharmaceutical industry was carried out. Stringent requirements were set for the building, in particular a very low permeability was required against the relatively high water-table. The design of the building, as well as the quality of the concrete, was concerned with providing an impermeable barrier, besides structural safety and functionality. Different concrete qualities were used for different parts of the building. The most critical areas were built with steel fiber reinforced concrete (SFRC), both precast and cast in situ. In particular, some slabs were cast in situ with self-compacting (SCC-SFRC). Concrete samples were cast on site and taken to the laboratory for testing mechanical and durability performance. In order to verify the degree of impermeability reached in the end product, on site air-permeability measurements were conducted on representative elements of the structure. The paper presents and analyzes the air-permeability results obtained on several different elements, concluding that the cast on site SCC-SFRC presents a unique extremely low permeability and that the external wall tested has an air-permeability low enough to withstand the environment to which it is exposed. On the contrary, some non-critical internal elements, both cast on site and precast, present rather high and scattered air-permeability values.