Determination of fracture mechanisms of reactive powder concrete (RPB) beams by acoustic emission method

Reactive powder concrete (RPB) is a high-performance-concrete that contains high amount of cement. With increase in structural use of RPB, recognition and standardization of its mechanical and fractural behaviour is in need. Although many studies have been conducted on material development, studies investigating bending behavior and fracture mechanisms of RPB beams are limited. Acoustic emission (AE) method is one of the frequently used nondestructive techniques to detect and monitor the defect and its progress. It is possible to determine development and motion of micro cracks under loading in RPB by using AE method. This study consists of three parts. Firstly, preliminary RPB castings were carried out and optimum RPB mixing was obtained. Afterwards RPB beams which were 125x250x1500 mm in dimension and containing 3 different reinforcement details were produced under the laboratory conditions. Finally, fracture mechanisms of these three beams were investigated by mechanical and AE tests. As a result of the tests, the points where the average frequency decreases and the AE energy increases indicate to fracture of the elements. The more ductile RPB beamhad much more micro cracks with more number and with less energy Steel fibers retard the development of macro cracks and thus, the beam behaves more ductile although it fails due to shear and gradual increases occur in AE graphs. Keywords: reactive powder concrete, RPC, acoustic emission, AE, fracture mechanism.