Experimental validation and fracture properties analysis on wedge splitting concrete specimens with different initial seam-height ratios

Abstract

In order to study the fracture properties of non-standard concrete wedge splitting tensile specimens with different initial seam-height ratios and the impact on concrete fracture toughness based on aggregates cohesive force, five groups non-standard concrete wedge splitting specimens with different initial seam height ratios as 0.2, 0.25, 0.3, 0.35 and 0.4 were designed and constructed for the experiment. Based on double-K fracture model and fictitious crack model, a new fracture toughness calculation model for non-standard concrete wedge splitting tensile specimen with different initial seam height ratios was built. The results showed that: the value of initial cracking load Pini and unstable fracture load Pun decreased gradually with the increase of specimens’ initial seam height ratio. With the increase of seam height ratios, the value of the critical effective crack length ac showed a linearly increasing trend, but the subcritical crack propagation length Δac showed a decrease trend. The unstable fracture toughness KunIC and the cohesive toughness KcIC were affected by seam height ratios, decreased with initial seam height ratios increasing, and the initial fracture toughness KiniIC was independent of it that could be treated as material constant. When calculating the initial fracture toughness KiniIC, the model in this paper could eliminate the errors caused at the moment of determining initial cracking load Pini, which proved its advantage. For the specimens with smaller initial seam height ratio, its fracture features was influenced by maximum tension stress and showed some shearing failure.