The effect of shrinkage cracks on the load bearing capacity of steel-fibre-reinforced roller-compacted-concrete pavements

Abstract

This paper demonstrates the effect of shrinkage cracks on the static load bearing capacity and on the fatigue performance of RCC pavements reinforced with steel fibres recycled from post-consumer tyres, with the aid of a case study. A numerical method is adopted using material properties (moisture transport, free shrinkage, mechanical and fatigue) derived from experiments. It is shown that surface micro-cracks initially develop predominantly due to differential shrinkage (curling). These micro-cracks penetrate down to approximately a quarter of the slab thickness and it is shown that they reduce the ultimate load bearing and fatigue capacity of the pavement by up to 50 %. Even though shrinkage does not initially induce visible cracks, it significantly intensifies the crack opening due to traffic load by up to 500 % for a crack width of 0.5 mm. For the case studied herein, to assure the long-term performance of the pavement the allowable stress ratio should be reduced by half, to account for the effect of shrinkage distress. This study is useful because for the first time the mechanical characteristics are coupled with the moisture transport mechanism, as well as the shrinkage and fatigue characteristics. This methodology can be used for other similar materials and geometries and can lead to general conclusions regarding the importance of shrinkage distress on the design of pavements.