Fracture of bonded cement based materials is complicated due to not only bonding itself but also heterogeneous genuine nature of cement-based materials. This study investigates the fracture parameters that obtained from the mechanical fracture tests and the post-peak behavior of bonded cement-based materials. Fracture parameters were analyzed such as the critical stress intensity factor, the critical crack length and the critical crack tip opening displacement. In addition, this study defines a new fracture parameter, the critical crack opening angle, which describes a crack opening resistance. In order to evaluate the fracture energy of quasi-brittle materials, it is typical to use the non-linear elastic fracture mechanics approaches. From the test results, however, it is known that the toughening action at the fracture process zone of the bonded interface has been significantly diminished because of the brittle fracture and the pre-determined weak crack path. Therefore, the post-peak behavior could be successfully estimated by using the suggested model that considered only the elastic deformations.