Characterisation of Strain-Hardening Cementitious Composite (SHCC) Under Cyclic Loading Conditions for Self-healing Applications

The ground shaking in an earthquake often imposes cyclic loadings on infrastructures placing them in danger. Concrete is quasi-brittle in tension and easy to crack under cyclic loadings. Fibre reinforced strain-hardening cementitious composites (SHCC) featuring high ductility, high energy absorbing capacity and controlled multiple cracking have been proposed for seismic-resistant applications. The fine cracks have been proved to not only improve the durability but also enhance the autogenous self-healing ability. This study focuses on investigating the material behaviour and self-healing potential of SHCC under cyclic flexural loading conditions. Four-point flexural tests (including monotonic and cyclic tests) were performed to study its mechanical properties and cracking behaviour. The surface crack widths were measured by optical microscopy. Results showed that 28-day air cured specimens exhibited a deflection capacity of up to 9.6 mm and an average crack width of 28 μm under monotonic flexural loading. Regarding the flexural stress-deflection curves, the envelops of cyclic testing results were close to monotonic results with both elastic and hardening phases. SHCC could still maintain fine crack widths (below 60 μm) under cyclic loading conditions. SEM/EDX test was conducted to investigate the fibre-matrix interface.