Document Type : Research Article
Faculty of Engineering, Ferdowsi University of Mashhad
Due to existence of cracks in concrete structures, the conventional strength criteria may not be able to predict their failure. It has been shown that the theories of fracture mechanics can predict the behavior of these structures, appropriately. In this experimental and analytical study, by using fracture mechanics theories, fracture parameters of flexural different specimens made of Engineered Cementitious Composites (ECC) are investigated. 24 flexural specimens with notch at their mid-length were manufactured and tested. Six of these specimens with the dimensions of 350×100×100 mm were conducted under Work of Fracture test Method (WFM) and other 18 specimens with the dimensions of 190×70×70 mm, 380×140×70 mm and 760×280×70 mm were studied under Size Effect test Method (SEM). The materials used for ECC included polypropylene fibers, cement, iron furnace slag, silica fume and stone powder. Two ratios of fibers (1 and 2%) were used in different mixtures of ECC. It was observed that by increasing fibers from 1% to 2%, the amount of flexural strength, fracture energy and failure toughness (KIC) of the specimens increased. On the other hand, compressive strength, characteristic length (Lch) and brittleness number of specimens decreased. The Bazant size effect law was also discussed for the ECC specimens.