Effect of Prefabricated Crack Length on Fracture Toughness and Fracture Energy of Fly Ash Concrete Reinforced by Nano-SiO2 and Fibers

This paper summarizes the test data obtained from an experimental investigation of nanoparticles and steel fiber-reinforced concrete. Tests were conducted to investigate the effect of prefabricated crack length on determining fracture parameters of concrete composite. The results reveal that most of the fracture parameters and the fracture relational curves of the concrete composite are influenced greatly by the prefabricated crack length of beam specimens, while the prefabricated crack length has little effect on the critical crack tip opening displacement. There is a tendency for effective crack length and the critical crack mouth opening displacement to increase with the increase in prefabricated crack length, while the initial fracture toughness, unstable fracture toughness and fracture energy gradually decrease. Besides, when the prefabricated crack length decreases from 50 to 20 mm, these relational curves become much larger, and the nonlinear stage of the curves become longer and longer, and the descent stage of the curves become flatter and flatter.