Abstract:The influence of mineral admixtures on brittle fracture of mortar was investigated through three-point-bending test.The research results show that the mineral admixtures have the ability of improving the brittleness of mortar in comparison with parameters of the fracture properties such as K_(1C),G_F and CTOD(crack tip opening displacement).It is also surely concluded that the replacement of 40%(by mass)mineral admixture has the best ability of enhancing K_(1C) and G_F.