ABSTRACT
2.2 Geometry of specimens Although the present method works equally well for several geometries, three-point bend beams are recommended for the purpose of standardization. The recommended specimen is shown in Fig. 1. It is a beam of width b, depth d and length L. The beam is loaded at mid-span by a concentrated load, and is simply supported over span l. A notch of depth a0 is cut into the cured beam at mid-length (Fig. 1). The loads are applied through one hinge and two rollers with the minimum possible rolling friction. The concentrated load as well as the support reactions, which represent uniformly distributed line loads across the beam width, are applied over bearing plates whose thickness is such that they could be considered as rigid. The bearing plates are either glued with epoxy or are set in wet cement. The distance from the end of the beam to the nearest support must be sufficient to prevent spalling and cracking at beam ends.
