Strength and Size Effects in Fiber Reinforced Materials

The paper presents experimental evidence and an explanation of the size effects on structural strength and post-peak behavior observed in high strength concrete beams under three point bending. The microcrack evolution of plain concrete and fiber reinforced concrete were investigated with acoustic emissions and electronic speckle pattern interferometry. When steel fibers are introduced in the concrete mix, the size effects are usually less pronounced on the structural strength and ductility, but the considered size ranges show that the fiber length should be chosen adequately relative to the size of the specimen.