University of Technology Sydney. Faculty of Engineering and Information Technology.Engineered Cementitious Composites (ECC) is a unique class of high-performance fibre reinforced cementitious composites (HPFRCC), exhibits high tensile ductility with the tensile strain capacity up to 5% with a moderately low synthetic fibres fraction (typically 2% or less by volume). ECC typically utilises short synthetic fibres, such as polyvinyl alcohol (PVA) or polyethylene (PE) fibres, which are tiny in diameter. These fibres are flexible, i.e. they can be bent or coiled in the matrix of ECC. Notably, the orientation of a bent or coiled fibre varies at different cross-sections of the specimen, leading to the divergence of ECC behaviour. Hitherto, a reliable approach that can provide a full understanding of the orientation and distribution of flexible synthetic fibres in the matrix of ECC and practical information of fibres orientation and distribution for estimating the tensile performance of ECC has not been reported.
In this PhD research, a numerical model was first developed to simulate the flow of fresh ECC, particularly focused on the flow characteristics of self-consolidating or flowable ECC. The numerical results of modelling several standard tests at the fresh state of flowable ECC, including the flow cones, V-funnel and U-box tests, were found to be consistent with experimental data. Through these validations, the developed model has proved its capability of providing insight into the flow behaviour of self-consolidating ECC in terms of filling, passing abilities and the distribution/orientation of flexible synthetic fibres at its fresh state. To take advantage on the understanding of the orientation distribution of flexible synthetic fibres from the developed model above, a novel fibre-bridging model at the hardened state of ECC was then proposed through considering the two-way pullout mechanisms of an arbitrary inclined fibre. The findings of the proposed fibre-bridging model reveal much better agreements with the experimental testing data in comparison with existing models, especially during the pullout stage of fibre. Finally, a novel approach was proposed for estimating the tensile performance of ECC through combining two states of ECC modelling