The Double Cantilever Beam (DCB) Mode I fracture testing has been widely used in fracture testing of especially fiber reinforced polymer composites and adhesive joints. Application of classical DCB testing to plain concrete or unreinforced ceramic specimens is not straightforward and cannot be carried out as in fiber reinforced polymer composites. Instead, an indirect tension approach is proposed in this study. Tests of notched geometrically similar DCB specimens made of normal and high strength concretes loaded eccentrically at the cantilever beam-column ends in compression have been carried out. Classical Type II size effect analyses of peak loads obtained from these tests are performed. The Microplane Model M7 is calibrated independently using uniaxial compression tests and employed to predict the peak loads of both tested and virtual geometrically similar DCB specimens. The same size effect analyses are performed on the predicted peak loads and the errors in the fracture parameters of the classical size effect analysis are determined. (C) 2018 Elsevier Ltd. All rights reserved.