Tentative Characterization of Old Structural Concrete through Mechanical Fracture Parameters

Structural concrete of the building of Vítkovice railway station from 1970s is characterized via mechanical fracture parameters. In this paper, six core-drilled cylindrical specimens with diameter of 75 mm were provided by a Chevron type notch of depth of 12 mm. Three-point bending fracture tests were conducted on these specimens supported as beams with the span of 170 mm. Load vs. deflection and load vs. crack mouth opening displacement diagrams were recorded from which modulus of elasticity (E), fracture toughness (KIc) and fracture energy (GF) were determined using linear elastic fracture mechanics approach and work-of-fracture method. Mean values of these parameters (with their coefficient of variability) were obtained as follows: E = 39.4 GPa (29.1%), KIc = 0.90 MPa·m1/2 (18.5%), GF = 174.0 J/m2 (26.0%). These parameters can serve as first guess or indicative values for structural assessment and life-time predictions.