•The number of articles on concrete healing being generated worldwide is increasing.•Basic mechanical tests are commonly used to prove the efficiency of healing.•Few studies investigate internal crack distribution and morphology during healing.•Healing is assessed using novel methods based on X-ray tomography, MIP tests.•Porosity, sphericity, single crack width, and Structure Model Index are discussed. Researchers have put significant effort into developing various healing agents for micro-crack closure to achieve a more durable structure and various destructive and non-destructive test methods are often used for the evaluation of concrete self-healing. In this paper, the use of the X-ray tomography and Mercury Intrusion Porosimetry is reviewed as the most advanced non-destructive test methodologies for the evaluation of concrete self-healing at the micro-structural level. The capabilities of the two test methods in correlation to self-healing in cementitious materials are presented via the void content, crack width/pore diameter and crack volume measurements. In addition, the paper suggests the geometrical aspect of voids as an alternative type of analysis for evaluating self-healing in cementitious materials.