Einfluss des Kontakts zwischen Mauerstein und Mauermörtel auf das Drucktragverhalten von Mauerwerk

At first, as part of a literature review, the state of knowledge on the load bearing behaviour of masonry under compressive load was comprehensively presented. It has been shown that the stress-strain curves of the materials significantly differ, and, particularly concerning the multiaxial behaviour, only few studies are available so far. With regard to the properties of the mortar in the joint, the suction behaviour of the masonry units was identified as an important influencing parameter. While the effect on the compressive strength of the joint mortar has already been subject of various investigations, there is little information about the influence of water abstraction on the deformation properties of the mortar in the joint. However, these investigations indicate that the modulus of elasticity of the joint mortar is only a fraction of the value determined on the unaffected mortar. After explaining the stress conditions prevailing in masonry under compressive load, the procedure used for deriving compressive strength values based on compression test on masonry walls was described. Furthermore, empirical approaches and theoretical models for the determination of the masonry compressive strength were presented and discussed. Based on the knowledge gained from the literature research, investigations were carried out on masonry units, masonry mortar and masonry pillars. It was found that in case of the masonry pillars made of autoclaved aerated concrete units the joint compressive strength increased significantly compared to the compressive strength of the mortar prisms hardened in steel formworks, whereas in case of the masonry pillars made of calcium silicate units, it fell due to the different capillary suction. In addition, the influence of the joint thickness on the compressive strength could be shown. The investigation of the bonding properties showed that the adhesive shear strength between units and mortar was comparatively low and the experimental values were strongly scattered within the test series. ...