13th International Conference on Fracture June 16–21, 2013, Beijing, China -3- 3.2. Fracture Resistance The values of the maximum loads obtained during the bending tests according to the notch root radius (ρ) of the specimens are presented in Tables 2, 3 and 4 for the different types of mortars. In these tables, the maximum load corresponds to the average of three tests. Table 2. Maximum load to the notch root radius for the plain mortar ρ (mm) Maximum Load (N) unnotched 1539.1 ± 17.3 0.5 359.1 ± 20.6 1.0 368.5 ± 15.3 1.5 391.9 ± 16.1 2.0 397.1 ± 6.4 2.4 437.2 ± 51.6 Table 3. Maximum load to the notch root radius for mortar reinforced with 25 mm fibers ρ (mm) Maximum Load (N) unnotched 2195.2 ± 66.5 0.5 801.0 ± 60.1 1.0 845.9 ± 99.7 1.5 858.4 ± 81.1 2.0 992.1 ± 52.2 2.4 1074.0 ± 83.9 Table 4. Maximum load to the notch root radius for mortar reinforced with 45 mm fibers ρ (mm) Maximum Load (N) unnotched 2453.2 ± 47.0 0.5 1014.8 ± 44.4 1.0 1127.9 ± 26.7 1.5 1190.6 ± 28.9 2.0 1225.4 ± 35.2 2.4 1494.9 ± 31.9 The load carrying capacity of all mortars considered in the present study decreased with the presence of notches in the specimens. Concerning the notched bend specimens for all mortar conditions, the ultimate load was found to decrease as the notch became sharper. However, the incorporation of sisal fibers by the mortar was associated with an appreciable increase of the ultimate load during the tests, with the long fibers being more effective in promoting mortar resistance than the 25 mm fibers. The J-integral values at maximum load (Jm) were calculated from the integrated energy (U) under the load displacement curve, using the Rice estimation formula [7]. The variation of Jm with the notch root radius for the plain mortar is presented in Fig. 1.
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