The effect of fly ash content on flexural performance and fiber failure mechanism of lightweight deflection-hardening cementitious composites

[Display omitted] •Deflection-hardening cementitious composites with low fiber content were developed.•The strength-ductility balance of LDHCC was achieved.•The critical fly ash content was determined as 25%−37.5%. Experimental studies were carried out to investigate the effect of fly ash content on the failure mode of fibers in lightweight deflection-hardening cementitious composites (LDHCC) with fly ash cenospheres and 1.2 vol% of polyvinyl alcohol fiber. The aim is to achieve strength-ductility balance of LDHCC via determining the critical fly ash content at which the failure mode of considerable fibers shifts from fracture to pull-out. Mechanical behavior and fiber failure mechanism of LDHCC with different fly ash content were investigated and the results were then used to analyze the failure process of LDHCC. High specific strength and flexural toughness could be achieved at the critical fly ash content which was found to be between 25% and 37.5% for 1.2 vol% of PVA fibers.