Study of the distribution and orientation of fibers in SFRC specimens

Abstract

In steel fiber reinforced concrete (SFRC), the fibers are generally considered to be oriented isotropically. However, it is known that the procedures used in the specimen fabrication during quality control and material characterization may influence the distribution of the fibers significantly. This has an important effect on the properties determined from the specimens, which has to be considered when the results are used to analyze the behavior of other elements. In the present work, the orientation and segregation of fibers in cylindrical specimens and prisms, which are normally used in the mechanical characterization of SFRC, are evaluated. The type of compaction (i.e., table vibration, hand tamping and internal vibration) is seen to have a considerable influence on the distribution of the fibers. In the prisms, table vibration increases the tendency for the fibers to be oriented horizontally. In the cylindrical specimens, hand tamping appears to cause the least non-uniformity of the fiber distribution. The study was conducted on conventional concretes with 40 kg/m3 of fibers.