Many attempts have been focused on the textile reinforced mortar structures. The advantages of textiles are mainly a very good load bearing capacity, excellent ductility, thin size and light weight of components, resistance to corrosion, and no magnetic disturbances. Such structures are expected to have wide application foregrounds. The transfer of forces from reinforcement to mortar is accomplished through a bond. Therefore, understanding and further improving bond properties of textiles in mortar are important. In the paper, bond characteristics of various textiles in mortar obtained from pull-out tests and numerical simulations are shown and compared. The textiles used include carbon, alkali resistant glass and aramid. They were plain and impregnated with epoxy resin. Prestressed and nonprestressed specimens were tested. The experimental results show that epoxy resin impregnating and prestressing can strongly enhance the bond strength. Numerical simulations show good agreement with the experimental results and significantly contribute to a better understanding of the bond characteristics of textiles in mortar.

The influence of the fracture process zone (FPZ) on the fracture properties is one of the hottest topics in the field of fracture mechanics for cementitious meaterials. Within the FPZ in front of a traction free crack. Cohesive forces are distributed in accordance with the softening stress-separation constitutive relation of the material. Therefore, further crack propagation necessitates energy dissipation, which is the work done by the cohesive forces. In this paper gƒ the local fracture energy charaxterizing the energy consumption due to the cohesive forces, is discussed. The computaional expression of gƒ in the FPZ can be obtained for any stage during the material fracture process regarding the variation of FPZ, whether in terms of its length or width. Gƒa, the average energy consumption along the carack extension region. hsa also been computed and discussed in this paper. Thee experimental results obtained from the wedge splitting tests on specimens with different initial notch ration are employed to investigate the property of the local fracture energy gƒ and the average value Gƒa over the crack extension length. These results can be used to indicate the influence of the FPZ. Additionally, changes in the length of the FPZ during the fracture process are also studied.

A simplified method for determining the double-K fracture parameters Kini Ic and Kun Ic for three-point bending tests is proposed. Two empirical formulae are used to describe the crack mouth opening displacement CMOD and the stress intensity factor Kc I caused by the cohesive force σ(x) on the fictitious crack zone for threepoint bending beams. It has been found that the two empirical formulae are accurate for a large practical region of a/D. Experiments carried out by many researchers showed that the new formula of CMOD for three-point bending beams can be directly used to predict the initial crack length for precracked beams, the notch depth and the critical effective crack length, as well as the crack length in the post-critical situation with a satisfactory accuracy. Further verification is demonstrated to determine the double-K parameters Kini Ic and Kun Ic. They are very close to those determined by the method proposed in our previous work. Using the simplified procedure, the experiments can be performed even without a closed-loop testing facility and the calculation can be carried out on a pocket calculator.

Assuming the weakest link concept. A probalilistic model of fracure in concrete structures has been developed in terms of the critical stress intensity factors. The probabilistic model, wodel, which is expressed in the form of the Weiball distribution, has been compared with arange of experimental results in the literature. The results predicted by the formula are in good agreement with the values reported in the literature for four test secimen geometries-compact tension spectimens, notched three-point bend specinens, wedge splitting spectimens and compact compression specimens. The results presented in the paper have been applied to predict the fracture in large concrete dams and the results compare favourably with observed craking.

Continuing the experiments on the double-edge notched pecimens on which the mode Ⅱ fracture toughness KIIc of concrete was measured, a practical testing approach to determine mode Ⅱ fracture energy GIIF is studied using the same geometry.