Synergistic Effect between CaCO3 Whisker and Steel-PVA Fiber Cocktail in Cement-Based Material at Elevated Temperature

A new fiber cocktail reinforced cement–based materials (NFCRCM) with steel, polyvinyl alcohol (PVA) fiber, and calcium carbonate whisker (CCW) was developed to obtain powerful fire resistance in this paper. The flexural properties, synergistic effects, and microscopic mechanism of NFCRCM at elevated temperature were particularly studied. With the introduction of CCW, the degradation of flexural strength and toughness of steel-PVA fiber cocktail reinforced cement–based materials below 800°C was decreased. Below 800°C, the NFCRCM with 1.5% steel fiber +0.5% PVA fiber +3% CCW showed a significant positive hybrid effect in flexural strength and toughness resulting from microscopic crack inhibition and nucleation effect of CCW. When the temperature reached 800°C or above, a negative hybrid effect was generally observed due to thermal decomposition of CCW.