ABSTRACT
Abstract This paper examines the interplay between aggregate size, interface toughness and structural effects in dictating the apparent size effect in aggregative solids like concrete. In concrete, tensile strength is limited by the growth of flaws around the mortaraggregate interface and subsequent branching into the matrix. Tension tests confirm that decreasing aggregate size increases tension strength, contrary to a power law size effect. A branching model is developed and used to explain experimental observations on size effect and to show that interface toughness affects brittleness. Keywords: aggregate size, interface fracture toughness, concrete, branching, brittleness.
1 Introduction The study of size effects in the failure of heterogeneous materials has been an important field of research for some time. The work began with the power law relationship between failure stress and specimen size given by Leicester [1], but gained considerable impetus through the size effect work of Bazant [2] and Carpinteri [3].
