tesi A. Caggiano.pdf - EleA@UniSA - Università degli Studi di Salerno

1 Introduction1.1 Scientific framework and general overviewIn the last century, concrete has become the most widely used construction materialand, then, a great part of the existing built stock, as well as the majority of infrastructurescurrently under construction are made of Reinforced Concrete (RC). In spite of the widevariability of the relevant physical and mechanical properties of cohesive-frictionalmedia, cement-based materials like concretes are characterized by low strength andbrittle response in low confinement and tensile stress states. These deficiencies canbe mitigated by randomly adding short reinforcements into the cementitious mortar[Gettu, 2008].The development of innovative cementitious materials, going to the direction of HighPerformance Concretes (HPCs) in general sense, represents a new field of interestof the Material Science and Structural Engineering. In this sense, Fiber-ReinforcedCementitious Composite (FRCC), obtained by randomly mixing short fibers (made outof steel, plastic, natural materials, recycled reinforcements, etc.) into conventionalcementitious materials, is a structural material characterized by a significant residualtensile strength in post-cracking regime in comparison to plain concrete and enhancedcapacity to absorb strain energy due to fiber bridging mechanisms across the openingcracks [Brandt, 2008, di Prisco et al., 2009, Nguyen et al., 2010].Fiber-Reinforced Cementitious Composites (FRCCs) may result in a less brittle andpossible quasi-ductile behavior, even in the case of tensile loading, and exhibit strainhardeningprocesses with multiple cracks and relatively large energy absorption priorto failure. Composites with these relevant features take the name of High PerformanceFiber-Reinforced Cementitious Composites (HPFRCCs) [Naaman and Reinhardt, 2006].1