STEEL MICRO-FIBRE REINFORCED HIGH STRENGTH

Fracture parameters of high strength mortar incorporating steel micro-fibres were investigated by means of direct tensile tests and three point bend tests. Uniaxial tensile tests were performed on unnotched and notched cores. The peak value measured on unnotched specimens was considered as the true tensile strength of the material. The maximum load/net-cross-section ratio of the fibre reinforced specimens was always found to be higher in the unnotched case than in the notched one. However, when there was no fibre in the mix (matrix alone), the ratio maintained a constant value whether the specimens were notched or unnotched. The results are discussed according to the fibre distribution in the fracture area. It was found that the strength can be related in an unique way to the number of fibres. This correlation was less tight when the post peak behaviour was concerned. In the same way, three point bend tests on notched beams gave results which depend, in terms of residual capacity, on the number of fibres crossing the ligament. Applying the concept of a cohesive crack, the direct tension results were used as input data to model the response of the flexural test. Calculations pointed out that slight differences, apparently negligible, in the casting of samples may significantly alter the softening behaviour.

• INTRODUCTION

• EXPERIMENTAL PROGRAMME

• SPECIMENS

• RESULTS AND DISCUSSION

• MODELLING

• CONCLUDING REMARKS

• REFERENCES