With the recent developments in modelling the shear behaviour of reinforcement concrete (RC) members without transverse reinforcement, the contribution of aggregate interlock has been more and more recognized as one of the critical components in the shear resistance of RC members. This paper presents a study on the aggregate interlock action utilizing laser scanned crack surfaces including the shear crack surface of a 1.2 m concrete beam. The study extends the classic aggregate interlock model proposed by Walraven to enable the possibility of employing modern measurement technology.