Comparative flexural performance of compacted cement-fiber-sand

Abstract

This research investigates the influence of seven different fiber types on the flexural performance of compacted cement-fiber-sand (CCFS) with four fiber fractions (0.5, 1, 1.5 and 2% by volume). The seven types of fibers are 12 mm polypropylene, 19 mm polypropylene, 40 mm polypropylene, 55 mm polypropylene, 33 mm steel, 50 mm steel and 58 mm polyolefin fibers. The overall CCFS performance was divided into seven sub design performance indicators: (1) peak strength; (2) peak strength ratio; (3) residual strength ratio; (4) ductility index; (5) toughness; (6) equivalent flexural strength ratio; and (7) maximum crack width. The interaction mechanism of the fiber/cement-sand interface was investigated by scanning electron microscopy. Finally, the effectiveness of each fiber type was compared and rated in terms of the overall performance. The results show that the 50 mm steel fiber provided the best overall sub performance, resulting in an excellent overall flexural performance; in comparison, the 12 mm polypropylene fiber exhibited very poor performance. However, the 19 mm polypropylene and 33 mm steel fiber specimens provided very good and good overall performances, respectively. The nature of the fiber surface and the fiber length affects the overall performance of CCFS. The surface of the steel fibers, compared to the other synthetic fiber types, is more hydrophilic and is more compacted in a cemented-sand matrix without separation of the interfacial zone, providing the best overall flexural performance.