Enhanced specimen size and shape effect models for high-strength fibre-reinforced concrete Available to Purchase

The present study investigates the influence of using steel fibres on the geometry and shape effects in high-strength concrete mix designs. The results obtained are indicative of the reliability of size-effect models when fibres are added to mixtures. The size- and shape-effect models of Nevile, Kim and Yi, the modified size effect law (MSEL) and the size effect law (SEL), along with the combination of SEL and fractal theory, are investigated. Then, in order to examine these models, beams with initial notch and constant size, as well as cubes and cylinders of different sizes, are tested. It is evident by using the MSEL model that the addition of fibres decreases the effect of size. The declining slope of the MSEL curve demonstrates that the effect of geometry is reduced by adding steel fibres. The combined model of SEL and MSEL reveals that by adding fibre the cubic and cylindrical specimens behave in a more ductile way, and hence the size effect is reduced. Furthermore, the impact of utilising silica fume at various replacement levels in the contents is examined. Findings reveal that, contrary to fibre addition, replacing cement with silica fume in the mixes increases the geometrical strength ratio.