Quasi-brittle fracture analysis of large and small wedge splitting concrete specimens with size from 150 mm to 2 m and aggregates from 10 to 100 mm

• A simple closed-form solution is derived for determination of tensile strength f t and fracture toughness K IC from WS tests. • The solution is examined against three sets of concrete specimens with size up to 2.3 m and maximum aggregate size of 100 mm. • An effective average aggregate size d av is statistically determined for each concrete mix, and used in the analysis. • Both geometrically similar and dissimilar WS specimens can be analyzed together. • Common curve fitting is replaced by normal distribution analysis which provides reliability band (e.g. 95%) besides the mean. The wedge splitting (WS) test geometry, suitable for testing large concrete specimens up to a few meters in size because of the self-weight supports, will find more applications if a closed-form model is available. This study presented a linearized boundary effect model (BEM) on quasi-brittle fracture of large WS mass concrete specimens containing aggregates up to 100 mm. Two separate small WS specimens containing aggregates around 10 mm and 20 mm were also analyzed to show the versatility of the model and the necessity to include the aggregate size in modelling. Modelling concrete as a large particle composite led to a simple closed-form solution, and both the fracture toughness K IC and tensile strength f t for the formation of the crack/notch-tip fracture process zone (FPZ) were determined from the maximum splitting force P max-h of WS specimens. The material properties K IC and f t from the current WS model were also confirmed by three-point-bending (3-p-b) tests of the same concrete. Comparison between the linear BEM and the well-known size effect law (SEL) was provided for purposes of experimental data analysis and mathematical fitting principles.