Granular materials forming part of geotechnical structures like flexible pavements or embankments experience abrasion and crushing as a result of static and dynamic loads applied during the compaction process or during operation. Despite of the research that has been conducted to date on how to evaluate abrasion and crushing and what effect they will have on the engineering properties of these granular materials, most of the experimental techniques to evaluate crushing are based on destructive measurements made after testing. In this paper the Acoustic Emission technique is used as a tool to asses crushing in a non destructive way. The results show that there is a close relationship between the acoustic emission and the development of plastic strains. Also the results show that the acoustic emission in granular materials is the results of both: sliding between particles, and crushing.