Micro crack characterization in concrete under uniaxial tension

The microcrack properties in concrete and low volume short fibre reinforced concrete under uniaxial tension have been characterized using an acoustic emission (AE) technique. To obtain overall information on micro cracking, a newly developed test method is used to ensure stable measurement of post-peak response. The phenomena of micro cracking localization are investigated by interpreting the locations of AE event sources. It is, found that localization does exist and starts before peak load. The AE activities are further investigated using a quantitative analysis technique. The 2-D moment tensor representation of each event, assumed to be a point source, is deduced. By interpreting the behaviour of the dipole, forces, the orientation, and the movement of micro cracks are inferred. The results show that the behaviour of a micro crack might be different from the behaviour of a macroscopic crack.