Sustainable roof elements: a proposal offered by cementitious composites technology

The use of High Performance Fibre Reinforced Cementitious Composites al-lows the designer to reduce the dead weight of roofing keeping concrete covering structures still more competitive in relation to steel structures in terms of costs, thermal and acoustic insulation and fire resistance. Thin slabs can be used as ter-tiary elements in roof decks beside the spandrel beams and the simply supported prestressed precast roof elements. 2m wide elements, simply supported along a 2.5 m span were devised as a possible application in this paper: the high performances are mainly used for the bending behavior along the 2.5m span and in order to drastically simplify the detailing of the support regions. The idea is that of coupling textile and UHPFRC technology, by means of an interposed polystyrene layer. A wide experimental investigation is in progress to mechanically characterize the materials in uniaxial tension and compression, in order to identify all the data needed for design like toughness, bending resistance, fire resistance and durability. As for the UHPFRC, in the research, the check of the ductility and the identifi-cation of the mechanical characteristics in tension are performed by means of bending tests carried out on unnotched specimens according to Italian Recom-mendations CNR DT-204 and of a new test (Double Edge Wedge Splitting test) recently proposed, while third point bending test as suggested in EN14651 is used to classify the material production. With reference to textile materials, they are reinforced with glass fabric and ran-domly dispersed glass or PVA fibres. The mechanical characteristics are deduced in uniaxial tension, while the structural behavior of the composite will be tested in bending. A modeling of the structure tests based on beam theory is also discussed.