Aggregate interlock is one of the most significant stress transfer actions in cracked concrete and its understanding is fundamental in order to predict the strength of many concrete structures, particularly members failing in shear. Several test programmes focusing on aggregate interlock have been reported in the literature. These programmes, however, often investigate a limited number of parameters and concrete properties, and do not account for different imposed kinematics of the cracked surface.This paper presents some preliminary results obtained by the authors by using a test setup which allows performing tests on double notched specimens subjected to mode I, mode {II} or mixed mode displacements with imposed kinematics. A series of mode I tests on small specimens have already been performed and the results are briefly summarized. These tests were categorized depending on the type of the cracked surface (crack through the concrete matrix or at the interface between matrix and aggregates), with results showing a significant dependency on this parameter. A preliminary mixed mode test on a pre-cracked specimen is presented as well and the results are compared to tests from the literature with similar assumed kinematics.