Effect of fiber volume fraction on crack propagation rate of ultra-high toughness cementitious composites

• The effect of fiber volume fraction on crack propagation rate of UHTCC is investigated.
• The crack propagation thresholds of UHTCC with three different fiber fractions are calculated.
• The effect of fatigue loads on crack propagation rate of UHTCC is investigated.

An investigation on the fatigue crack propagation law and the effect of fiber volume fraction on crack propagation rate of ultra-high toughness cementitious composites is carried out in this paper. Three fiber fractions, 1.5%, 2.0% and 2.5% are adopted. The research result shows that multiple random cracks are generated for the fracture specimens of this material under fatigue load, while the crack number depends on fatigue stress level and fiber fraction. With the increase of fiber volume fraction, the crack growth threshold is improved, while the crack propagation rate is decelerated. Meanwhile, the crack propagation rate is obviously affected by the fatigue loads.