Theory of Critical Distances and static/dynamic fracture behaviour of un-reinforced concrete: length scale parameters vs. material meso-structural features

•Mesoscopic length scale parameters in un-reinforced concrete are investigated experimentally.•The experimental results are post-processed according to the Theory of Critical Distances.•Aggregates acts as barriers slowing down/affecting the crack propagation process.•The critical distance approaches the average distance between notch tip line and first aggregates.