Investigation of Damage Processes of Mortar in Different Aggregate Size by Acoustic Emission Characteristics

Abstract

In order to study acoustic emission (AE) characteristics of damage process of mortar in different aggregate size, mortar specimens were tested under axial compression in the experiment, the whole damage evolution processes were monitored by full-digital AE acquisition system. The effects of mortar in different aggregate size on damage processes and failure mode were conducted by cumulative AE energy, amplitude, peak frequency and the ratio N/E (hits/energy) respectively. The ratio of cumulative AE hits of each frequency band and amplitude band to the whole cumulative AE hits in different stress level were counted, and the difference and evolution process of microcracks of mortar in different aggregate size in the failure process were revealed. The results show that cumulative AE energy increase with the increase of aggregate size in mortar. Distribution of cumulative AE hits of each amplitude band versus the stress in different aggregate size are the same, and AE hits of each amplitude band increase sharply suggests that the specimen will be destroyed. Besides, AE hits focus on low-frequency band at low stress level, while all peak frequency bands are active at high stress level, and the aggregate size of mortar have significant influence on cumulative hits of each peak frequency band. The ratio N/E decreased with the increase of aggregate size, and which increased linearly with the increase of the stress.