An experimental study on acoustic emission energy as a quantitative measure of size independent specific fracture energy of concrete beams

Notched three point bend specimens (TPB) were tested under crack mouth opening displacement (CMOD) control at a rate of 0.0004 mm/s and during the fracture process acoustic emissions (AE) were simultaneously monitored. It was observed that AE energy could be related to fracture energy. An experimental study was done to understand the behavior of AE energy with parameters of concrete like its strength and size. In this study, AE energy was used as a quantitative measure of size independent specific fracture energy of concrete beams and the concepts of boundary effect and local fracture energy were used to obtain size independent AE energy from which size independent fracture energy was obtained.

Research highlights
► From the present experimental study, it was observed that AE energy released during fracture process of concrete could be related to fracture energy of concrete.
► Acoustic emission (AE) energy released during fracture process of concrete was used as a quantitative measure of size-independent specific fracture energy of concrete beams.
► The concepts of boundary effect and local fracture energy were used.
► It may be possible to obtain size independent AE energy from size independent fracture energy of concrete.
► Damage mechanics models related to concrete often use parameters such as crack density to predict changes in stiffness due to damage. Until now crack density has been a difficult thing to measure, but AE has the potential to provide information on crack density that could then be used to tune the continuum damage models.