2 Experiments
2.1 Testing method
Cubic specimens with natural or steel fibers were tested using the simple wedge-splitting procedure described by Tschegg (1990, 1991). A schematic of this testing method is shown in Fig. 1. A cubic specimen is placed on a narrow linear support in a compression-testing machine. A wedge splitting apparatus (consisting of a wedge and load transmission pieces) is placed into the groove of the specimen with a starter notch at the bottom of this groove. The wedge, starter notch, and linear support are vertically aligned allowing the load to be transmitted directly from the testing machine to the specimen, without producing any additional lateral loads or moments. The wedge transmits a force (Fm) from the testing machine to the specimen. The slender wedge transforms this into a large horizontal force component (Fh) and a small vertical component (Fv) which are applied to the specimen (see Fig.l(b)). The large horizontal component splits the specimen in a manner similar to that of a bending test. The total force (Fm) is measured by a load cell in the testing machine. Knowing the wedge angle (a) and the total force, the horizontal component (Fh) may be easily calculated. The small wedge angle yields vertical forces small enough to be considered negligible. Friction forces between the wedge and load transmission pieces are minimized by the use of rollers. The resulting rolling resistances are small enough to be neglected.