Using Calcium Carbonate Whisker in Hybrid Fiber-Reinforced Cementitious Composites

The multiscale nature and multiscale cracking behavior of cementitious composite determine its micro-, meso-, and macroperformance. A new kind of fiber hybridization containing steel fiber, polyvinyl alcohol (PVA) fiber, and cheap calcium carbonate (CaCO3) whisker (approximately $230 per ton) was designed to increase the multiscale cracking resistance for cementitious composites. Mechanical properties, microstructures, reinforcing mechanisms, and economic efficiency of this designed hybrid fiber-reinforced composite were presented. The results indicated that both the flexural strength and flexural toughness are significantly improved. Scanning electron microscopy images and fracture tests confirmed that the interaction of different fibers and multiscale cracks contributes to enhancing the mechanical properties of cementitious composite, which is also reflected in its deflection hardening performance and multiple cracking behavior. Moreover, it seems possible that the steel fibers and PVA fibers can be partly replaced with CaCO3 whiskers, which is very beneficial in decreasing the production cost of fiber-reinforced cementitious composites for large-scale construction project applications. (C) 2014 American Society of Civil Engineers.