Preliminary modeling of internal heterogeneities in fibre reinforced concrete

The Reactive Powder Concrete (RPC) is made of a very fine homogeneous and compact matrix, with short steel fibres. The material (matrix and fibres) is a composite and therefore heterogeneous. From this heterogeneity of the mechanical characteristics, elastic fields are influenced by the presence of fibres and are a function of the percentage of fibres as well as orientation of the fibrous reinforcement. During the preparation of the RPC the fibrous suspension is equivalent to a concentrated solution. The consequence is a local alignment of fibres, under effect of strong gradients of shearing, and a regrouping of fibres by cluster. The result is a particular configuration for the distribution from fibres within the structure. The purpose of this study is to model, with finite element method, the mechanical behaviour of RPC elements by taking into account internal heterogeneities. Ready-made structural elements (beams) have been tested under flexure. The comparison between numerical approach and experimental investigations confirms the role played by the internal heterogeneities on the mechanical behaviour before and after the initiation of cracking. Therefore, the results of this study can be used to understand how we can optimise the process of casting.