The structural size effect is known to affect failure that is controlled by two regions. The first is dominated by a constant stress at failure ductile behaviour, whereas the second follows classical LEFM brittle behaviour. The transition region between represents the greatest interest with respect to size effect in quasi brittle materials. This paper presents experimental data for a low cement refractory pre-fired to 1200°C (but tested at ambient conditions), showing that specimens do exhibit a size effect, and that typical sizes used in the process industry often lie in the nonlinear transition region. Fracture toughness has been shown to vary as a function of specimen size until the material displays brittle characteristics at which point fracture toughness appears to be a constant material parameter. © 1995.
Palmer, G. B., & Baker, G. (1995). Specimen size effect on fracture toughness for a low cement refractory. Theoretical and Applied Fracture Mechanics, 22(1), 51–61. https://doi.org/10.1016/0167-8442(94)00048-6