Tracking of Crack Formation in Concrete Using Acoustic Emission Method and Digital Image Correlation

The paper presents analysis of crack formation in a reinforced concrete beam using an acoustic emission method (AE) and a digital image correlation (DIC). The examined element was loaded monotonically until reaching 50 kN force during the three-point bending test. Six acoustic emission sensors (two on the left and right surfaces of the sample and the other two on the bottom surface) combined with three-dimensional location method were used to find the destructive processes. The optical measuring system ARAMIS (DIC) was used to verify the obtained results. This device help to specify the location of crack and track its development on the basis of the strain map. The crack width was measured in 6 sections, which were located in different positions of the element height with the use of ARAMIS software. First section was applied at the centre of gravity of the longitudinal reinforcement. The following cross-sections were set every 2 cm towards the top edge of the element. In the first part of the analysis, a graphical comparison of the strain map (obtained with ARAMIS system) and the location of events (obtained with AEWin software) was made. In the second part of the analysis, the obtained crack width results were compared with number of AE events counted in zones, which were defined around the previously mentioned sections. The statistical analysis (Pearson's linear correlation) shows that the number of recorded events depends on the maximum crack width, the average crack width as well as the crack width increase registered between successive load levels. The results of the study conclude that simultaneous use of DIC and AE methods provided complete information on local strain and damage location in concrete.