Reorientation of short steel fibres during the flow of self-compacting concrete mix and determination of the fibre orientation factor

A simple method has been developed to assess the orientation and distribution of short steel fibres in self-compacting concrete mixes during flow. The flow of self-compacting fibre reinforced concrete has been simulated using three-dimensional Lagrangian smooth particle hydrodynamics (SPH) which is simpler and more appropriate to use to simulate the flow and to monitor the distribution of fibres and their orientation during the flow. A probability density function (PDF) has been introduced to represent the fibre orientation variables in three dimensions. Moreover, the orientation variables of each individual fibre in an arbitrary two dimensional cross-section have been calculated using the geometrical data obtained from the three dimensional simulations. From these a new definition of the fibre orientation factor has been introduced and a method proposed for its determination from the fibre orientations monitored during the simulations. It is shown that this new definition gives results that are consistent with the expected reorientation of fibres towards the principal direction of flow. A method has also been proposed for its determination from image analysis on cut sections.