Study on mechanical acoustic emission sources in fresh concrete

Acoustic emission testing has proven very useful as a non-invasive monitoring method for several material processes. Recently several studies have emerged related to fresh concrete monitoring, as AE has the sensitivity to record waves from many different processes, even though no external load is applied to the specimens. Due to the complexity of the activity including among others formation of hydrates, settlement, water migration, early age cracking, the accumulated AE cannot be easily explained. In the present paper, two mechanisms of mechanical origin (aggregate and bubble movement through the paste) are isolated and the characteristics of their emissions are studied. Experimental results are complemented with numerical simulations to enhance the understanding due to the complexity of the wave propagation problem.