Abstract:Fracture properties of reactive powder concrete (RPC) which was reinforced in steel fibers,steel macro polyolefin hybrid fibers and steel polyvinyl alcohol hybrid fibers were studied by three point bending fracture test to investigate the effect of hybrid fibers on the toughness of RPC. It is found that compared to RPC specimens reinforced only by steel fibers, the crack tip of RPC specimens reinforced by hybrid fibers shows some micro cracks, their load deflection curves and load CMOD curves show an obvious secondary hardening phenomenon; compared to RPC specimens reinforced only by steel fibers, the peak load of steel macro polyolefin hybrid fibers RPC specimens and steel polyvinyl alcohol hybrid fibers RPC specimens increa ses by 544% and 854%, and fracture energy increases by 1384% and 885%, and fracture toughness improves by 1119% and 508% respectively, when steel fibers volume fraction is 15% and content of macro polyolefin fiber or polyvinyl alcohol fibers is 9kg/m3; specimens reinforced by three kinds of fibers show a perfect hybrid effect when the steel fibers volume fraction is 10%, while macro polyolefin fiber and polyvinyl alcohol fibers content is 30kg/m3 or 45kg/m3 separately; fracture properties of RPC show a significant improvement when steel fibers volume fraction is 10%15% and synthetic fibers content is 9kg/m3.