抄録
In the previous paper, the structural anisotropy of concrete relative to the casting direction has been characterized by tensile tests and the effects of the internal defects shown by tensile anisotropy such as the fissures under aggregates or bleeding channels were discussed. In this paper, the effects of coarse aggregate size and content on the tensile anisotropy of concrete were investigated mainly. The outline of conclusions is shown in Fig.6 : (1) The larger the coarse aggregate size or content, the lower the tensile strength of concrete. (2) The extent of the reduction in strength of t_S, the tensile strength when the stress was applied in the same direction as casting, was more remarkable than that of t_R, the tensile strength when the stress was applied at right angles to the direction of casting. (3) So, the larger the coarse aggregate size or content, the more remarkable the tensile anisotropy, because t_S tends to be lower than t_R in usual concrete. (4) It is suggested that the defects under coarse aggregates affects the tensile strength more considerably than the bleeding channels do in usual concrete. (5) The tensile strength, especially when the tensile stress was applied in the same direction as casting, is possible to be a sensitive indicator of internal changes of concrete.
