Influence of fiber mixture on impact response of ultra-high-performance hybrid fiber reinforced cementitious composite

The penetration resistance potential of ultra-high-performance hybrid fiber reinforced cementitious composite (UHP-HFRCC) was investigated at fiber content of 2 %. Plain cementitious composite (PCC) versus 12 groups of UHP-HFRCC materials with various fiber mixtures were adopted herein for comparative analyses. The uniaxial compression tests were conducted to determine the 7-d and 28-d compressive strength indicating that the steel fiber outperforms the polypropylene fiber and polyvinyl alcohol fiber in improving compressive strength. The subsequent penetration tests for each mixture UHP-HFRCC target were performed and the penetration resistant performance was evaluated in terms of depth of penetration (DOP) and crater area. The experimental results suggested that the penetration resistance improvement potential of steel fiber reinforced cementitious composite goes moderately ahead of that of the polypropylene fibers or polyvinyl alcohol fibers cementitious composite. For the UHP-HFRCC targets, the steel fiber proportion increase generally resulted in the reduction of DOP and crater area. Besides, the hybrid batch target with 3 kinds of fibers might exhibit greater penetration resistant performance compared to the steel fiber hybrid mixture with polypropylene or polyvinyl alcohol fiber. Cavity expansion analysis was applied to develop the DOP analytical model for UHP-HFRCC penetration whereby the target resistance parameter was best fitted. Finally, the fiber hybrid reinforcement effect of UHP-HFRCC on the penetration resistance was evaluated via the hybrid effect index. The combination of steel fiber and polypropylene fiber leads to a positive effect against penetration while the incorporation of steel fiber and polyvinyl alcohol fiber to cementitious composite generally poses a negative effect.