عنوان مقاله [English]
نویسندگان [English]چکیده [English]
Failure of many concrete and rock structures on the development of interior crack due to stress concentration at the crack tip shows the prominence of the fracture mechanism investigation of these structures. Using conventional methods for the design and analysis of steel, concrete and rock structures based on the criteria of stress and strength has raised many problems for the structure stabilities. Today, with increasing application of nanoparticles, studies focused on the effect of nanosilica on failure mechanism are rare. Addition of nanosilica to the concrete results in higher compressive, tensile and flexural strength; lower setting time and water permeability and higher resistance to chemical attacks. In this research, the internal mechanism of resistance and failure of concrete reinforced with silica nanoparticles was studied to achieve a better understanding of their mechanical behavior. For this purpose, various standard samples were studied including disc with a central crack (CSCBD) and cubes with similar mixtures (water, cement and aggregates), but different in the amount of silica nanoparticles (0, 0.5, 1, 1.5) in 7 and 28 days of curing time. Acoustic emission techniques (AE) was used for the monitoring of the failure process. It was revealed, parameters such as the number of count, stable and unstable crack growth, average frequency and RA index are also affected by varying the amount of silica nanoparticles in the concrete composition. The results showed that concrete with silica nanoparticles can withstand higher stress without unstable crack propagation. It is concluded that the addition of silica nanoparticles improves the fracture parameters of concrete.