Naveen Shetty¹, Georgios Livitsanos³, Dimitrios Aggelis³, Danny Van Hemelrijck³,
Martine Wevers², Koen Van Balen¹, and Els Verstrynge¹
1)  Building Materials and Building Technology Division, Department of Civil Engineering, KU Leuven,
Kasteelpark Arenberg 40, box 2448, 3001 Heverlee, Belgium
e-mail: naveen.shetty@kuleuven.be, koenraad.vanbalen@kuleuven.be, els.verstrynge@kuleuven.be
2)  Department of Materials Engineering, KU Leuven, Kasteelpark Arenberg 44, box 2450,
3001 Heverlee, Belgium
e-mail: martine.wevers@kuleuven.be
3)  Department of Mechanics of Materials and Constructions, Vrije Universiteit Brussel, Pleinlaan 2,
1050 Elsene, Brussels, Belgium
e-mail: georgios.livitsanos@vub.ac.be, daggelis@vub.ac.be, dvhemelr@vub.ac.be

Keywords: masonry, compression, crack propagation, failure mechanisms, Micro-CT

Abstract. The constituent materials of masonry include different brick and mortar types with various properties. The difference in the stiffness properties of these materials influence the observed failure modes under compression. The general hypothesis of the failure mechanisms in brick masonry under compressive loading relies on the difference between the Young’s modulus of brick and mortar. The aim of this paper is to visually confirm or question the above hypothesis about the behavior of masonry under compression using a high resolution X-ray micro-CT scanner. In this study, clay brick in combination with four different mortar types was analysed. Micro-CT is used to obtain insight in the triaxial stress state of the mortar joint under compressive loading. Tomographic scans were made at different load steps during compressive testing on small masonry samples of diameter 30 mm and height 48 mm. The failure progression in masonry which evolves from the initiation of micro cracks, over the propagation, interaction and coalescence into macro cracks has been observed. The crack propagation is observed based on the 2D processed images from the micro-CT scanning and is successfully linked to the hypothesis of the failure mechanisms in masonry.