Flexural toughness performance of hybrid fiber-reinforced RPC

Flexural toughness tests are performed to investigate the influence of hybrid fibers on the toughness of reactive powder concrete (RPC). The experiment uses different amounts of high-strength steel fibers and macro-polyolefin or micro-polyvinyl alcohol (PVA) fiber. Two kinds RPC, silica fume and ultra-fine cement RPCs, are prepared to compare their toughness performance. Steel fiber volume fraction is 1 and 2 % while synthetic fiber contents are 6, 9 and 11 kg/m(3). The effects of hybrid fiber on the toughness performance of the two kinds of RPC were discussed. Strain hardening characteristics of load-deflection curves of hybrid fiber RPC were achieved. The test results show that the toughness index of hybrid specimens of 1 % steel fiber and 1 % macro-polyolefin fibers is larger than that of specimens with only 2 % steel fibers, especially for ultra-fine cement specimens. Comparing specimens with only 1 % steel fibers and those with hybrid fiber, the toughness index T(7) of silica fume specimens increased by 47.3-98.8 %, whereas T(7) of ultra-fine cement RPC specimens increased by 82.3-215.6 %, respectively. For higher volume of steel fiber it is advised to use less amount of micro-PVA fiber.