Determination of the Fracture Energy of Concrete:Comparison of the TPBT and the WST Method

In a NORDTEST project two methods for determination of the fracture energy of concrete are compared; the Three-Point Bend Test (TPBT) and the Wedge Splitting Test (WST).The methods involve notched beams and notched, grooved cubes, respectively. The two methods are compared in relation to handling and precision (repeatability, reproducibility). Concrete with a water/cement ratio of 0.43 including fly ash as well as silica fume is investigated.The results show that WST is significantly faster to work with compared to TPBT, although the sawing procedure is more time consuming. Only when using laboratory prepared specimens cast in moulds with a negative groove time can be saved.With the experimental setup used in the majority of the testing, the GF determined according to the TPBT methods is generally higher than the GF determined according to the WST method. The results however seem to indicate that care should be taken in designing the supports in the beam test (TPBT) in order to minimize the resistance to axial movements.