Determination of Concrete Fracture Parameters from a Three-Point Bending Test

The mechanical behavior within the processing zone of concrete material can be well described by the crack bridging performance. The material properties related to the crack bridging are cracking strength, tensile strength, and the stress-crack width relationship. In general, the cracking strength is lower than the tensile strength of concrete. Crack propagation is governed by the cracking strength. This paper presents a method to determine the above material parameters from a three-point bending test. In the experiment, a pre-notched beam is used. Corresponding values of load, crack mouth opening displacement, and load point displacement are simultaneously recorded. From experimentally determined load-crack mouth opening displacement curves, the above-mentioned crack bridging parameters are deduced by a numerical procedure. The method can be used to evaluate the influence of coarse aggregate and cementitious matrix strength on the stress-crack width relationship, tensile strength, and fracture energy of concrete.