Fracture properties of hybrid fibers reinforced reactive powder concrete

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 54.4% and 85.4%, and fracture energy increases by 138.4% and 88.5%, and fracture toughness improves by 111.9% and 50.8% respectively, when steel fibers volume fraction is 1.5% and content of macro polyolefin fiber or polyvinyl alcohol fibers is 9 kg/m3; specimens reinforced by three kinds of fibers show a perfect hybrid effect when the steel fibers volume fraction is 1.0%, while macro polyolefin fiber and polyvinyl alcohol fibers content is 3.0 kg/m3 or 4.5 kg/m3 separately; fracture properties of RPC show a significant improvement when steel fibers volume fraction is 1.0%-1.5% and synthetic fibers content is 9 kg/m3. © 2016, Tongji University. All right reserved.