In construction, shotcrete is sometimes used in lieu of conventional concrete for reasons of cost or convenience. Shotcrete is advantageous in applications of repair, underground excavations, slope and surface protection. Unreinforced shotcrete, like unreinforced conventional concrete, is a brittle material that experiences cracking and displacement when subjected to tensile stresses or strains. The addition of fibers to the shotcrete mixture adds ductility to the material as well as energy absorption capacity and impact resistance. In this work, different kinds of fibers included steel, polypropylene (PP), polyvinyl alcohol (PVA) were compared. Large fiber-reinforced shotcrete panels were cast in construction site. Beams and cylinders of specific size were obtained from those panels fo...[ Read more ]

In construction, shotcrete is sometimes used in lieu of conventional concrete for reasons of cost or convenience. Shotcrete is advantageous in applications of repair, underground excavations, slope and surface protection. Unreinforced shotcrete, like unreinforced conventional concrete, is a brittle material that experiences cracking and displacement when subjected to tensile stresses or strains. The addition of fibers to the shotcrete mixture adds ductility to the material as well as energy absorption capacity and impact resistance. In this work, different kinds of fibers included steel, polypropylene (PP), polyvinyl alcohol (PVA) were compared. Large fiber-reinforced shotcrete panels were cast in construction site. Beams and cylinders of specific size were obtained from those panels for experimental purposes. With the same mix, concrete specimens were prepared at the same time. A series of laboratory tests such as notched flexural test , toughness index, permeability, and shrinkage were conducted. This seminar will discuss the difference in shrinkage between shotcrete and concrete specimens. It will also discuss the reduction in shrinkage of fiber-reinforced beam constrained by steel I-beam and associated cracking induced. The tension-softening diagram and toughness index of cementitious composites containing different fibers will also be mentioned. It was found that shrinkage was roughly the same between shotcrete and concrete specimens. However the peak load of tension-softening diagram and toughness index were larger in shotcrete members than those in concreting. It was because the mixture had a better compaction by the shotcreting process. Also, higher fiber volume will increase the residual load in tension-softening diagram and toughness index.