Fibre reinforced concrete : fracture mechanics methods applied on self-compacting concrete and energetically modified binders

Abstract: Fibre reinforced concrete (FRC) is a type of building material that is increasing in use. As new types on concrete develops the need to update the knowledge on the use of fibre reinforcement increases. This thesis covers test methods for FRC that ranges from standard beam tests to sophisticated uniaxial tension tests. The consequence of applying fibre reinforcement in concrete made using various modified cementitious binders has also been studied. The binders used in this study are energetically modified cements (EMC). They consist of a mix of ordinary cement and different fillers, which has been processed through a vibrating mill. The influence of fibre reinforcement in self-compacting concrete (SCC) has been studied with regard to its feasibility in full-scale production. The fibre reinforced SCC has been studied with regard to its ability to retain its workability after addition of fibres and on its toughness properties. Finally, early age concrete and its fracture mechanical properties have been modelled. FRC is often used in structures where its task is to distribute cracks originating from stresses caused by volume changes in combination with restraint. In these cases, the appearance of cracks is a time-dependent phenomenon that occurs mainly in early ages. In this study a finite element model for localisation of strains in discreete cracks, the Inner Softening Band model, has been adopted and implemented with a model for the visco-elastic behaviour of early age concrete.