An experimental study of bending resistance of multi-size PFRC beams

To study the effects of macro- and micro-fiber on the concrete beams, bending resistance tests were conducted on the polypropylene fiber-reinforced concrete beams. Stepwise loaded tests were carried out to obtain the load-deflection curves for different test pieces, cracking load values of the first inclined crack, recording and depicting crack development, changes in mid-span deflection of the test pieces, load-strain relationships of concrete, etc. The crack patterns and failure modes were observed. The research findings have shown that the ultimate load of the concrete beams doped with multi-size polypropylene fiber is 58.31 and 34.08% higher than that of ordinary concrete beams and concrete beams with single macro-fiber, respectively. Notably, the ultimate anti-bending bearing capacity of the beams significantly improves following the addition of macro-fiber. Polypropylene fiber can offset the defects caused by macro-fiber, remarkably suppress the development of cracks, and control the deformation of beams due to the effects of micro-fiber of different dimensions.