Fatigue Behaviour of Steel Fibre Reinforced Concrete Pavements

The design of rigid pavements subjected to increasing heavy wheel loads and high traffic volumes necessitates, over time, the design of thicker pavements. With the advent of steel fibre reinforced concrete (SFRC), there exist the possibilities of enhancing fatigue performance of rigid pavements by including fibres in concrete and bridging cracks once they form. In the first part of this investigation, a material level of study was undertaken to investigate the performance of three different types of SFRC. Testing on round panels was undertaken to determine fatigue resistance; several varying load levels were applied at constant amplitude. A series of matched direct uniaxial tension and prism bending tests were also undertaken to provide comprehensive material characterisation data. It was concluded that fibres improve the fatigue life of concrete and a design model was developed. The model was validated against a large pool of experimental data obtained through the course of this study and is shown to correlate well with the test data. Also in this dissertation, the development of a constitutive model is presented for SFRC for post-cracking fatigue damage during cyclic loops. Comparing the results of the model with test data shows that the model is capable of accurately predicting the overall cyclic fatigue loading response of SFRC. The model is also able to capture the change in the COD, the stiffness changes with increasing load cycles and the number of load cycles to failure. In the final part of this study, a novel experimental program was developed to investigate the performance of large scale plain and SFRC slabs tested under static and cyclic loading – the SFRC slabs were 20% thinner than plain concrete slabs. The results show that the thinner SFRC pavements can carry higher numbers of load repetitions compared to those of currently constructed of plain concrete, with excellent serviceability performance in terms of crack width propagation and deflection development