Acoustic emission signal ‘peak amplitude-distribution’ analysis related to concrete fracture under uniaxial compression

Abstract

Acoustic emissions (AE) released during the compressive fracture of cementitious materials have been subjected to analysis using ‘AE based b-value’ to study the fracture process. Identification of the ‘AE sources locations’ in three dimension is not always possible. With a minimum number of AE sensors mounted on the test specimen and by using the AE based b-value analysis, it is possible to study fracture process and the damage status in solids. The b-value of AE is calculated using the Gutenberg–Richter empirical relationship (G-R law), which is available in seismology. The details related to original G-R relation and it’s suitability for AE testing were discussed. In this article it has been tried to look into the variations of the AE based b-value in cementitious test specimens prepared with different cementitious mixture proportions. Effect of (i) coarse aggregate size in cementitious materials (ii) loading rate during compressive fracture process (iii) age of concrete on b-value variation were discussed. The trend of variation in AE based b-value during fracture process in concrete and mortar was different. It was observed that when the compression toughness of the cementitious material increases, higher b-values were observed. When the loading rate was high, quick cracking occurred and lower b-values were observed. As the coarse aggregate size in the cementitious material increases, the cumulative AE energy was higher. The reason may be due to the compression toughness of the cementitious material. The AE based b-value is useful to identify the different stages of compressive fracture process in solids.