Fracture of 0.1 and 2 m long mortar beams under three-point-bending

Two hugely different mortar beams with the volume ratio close to 1:1000 were tested under three-point-bending (3-p-b) to verify fracture predictions for the large and long (LL) structures from results of the small and short (SS) specimens. They differed by both size and geometry: SS specimens with span length S = 0.1 m, width W = 40 mm and S/W = 2.5, and LL beams with S = 2 m, W = 500 mm and S/W = 4. This study performed and analysed quasi-brittle fracture of 0.1 m SS specimens with initial notch a₀ from 1 to 25 mm for determination of tensile strength f_t and fracture toughness K_IC, from which fracture of 2 m LL beams with a₀ of 250 mm was accurately predicted. Experiment results from the two vastly different 3-p-b beams, highly heterogeneous SS and nearly homogeneous LL in comparison to aggregates, were analysed by the boundary effect model (BEM).