Abstract:
In order to promote the engineering application of steel fiber (SF)-polyvinyl alcohol (PVA) fiber-CaCO
3 whisker (CW) multi-scale fibers/cement composite, and investigate its fire resistance and high temperature resistance, the flexural properties and microstructure of the SF-PVA-CW multi-scale fibers/cement composite after high temperature were studied. The results show that with the increase of temperature, the residual flexural strength of the SF-PVA-CW multi-scale fibers/cement composite decreases overall, but decreases slowly below 500℃ and the the SF-PVA-CW multi-scale fibers/cement composite with 3vol% CW still increase. The flexural strength decreases sharply at 800℃ and above. The equivalent flexural strength based on JSCE SF4 was used to evaluate the flexural toughness. With the increase of temperature, the equivalent flexural strength of the SF-PVA-CW multi-scale fibers/cement composite decreases gradually. At the temperature up to 500℃, the addition of CW significantly enhances the crack restricting of SF, and the effect of small deflection stage is better than that of large deflection stage. The equivalent flexural strength decreases sharply at 800℃ or above, especially at large deflection stage. With the help of digital camera, optical microscope and SEM, the micro mechanism of the influence of high temperature on the flexural properties of the SF-PVA-CW multi-scale fibers/cement composite was revealed.