Characterisation testing of mortar joints used in precast wall-slab-wall structures

As found very frequently in existing precast wall-slab-wall structures in some Northern European countries such as the Netherlands, high-strength mortar is commonly employed to execute both wall-wall and foundation-wall joints featuring no mechanical devices, whereas non-shrink low-strength mortar is used to make up wall-slab connections, replacing fabric felt material under certain circumstances. Material characterisation testing is deemed necessary to establish whether these wet joints are strong enough to allow horizontal forces on a building to be carried through them, thereby preventing the onset of damage in the connectors’ sockets as well as the sliding of precast walls and eventually their toppling. In view of this, standard compression and three-point flexural tests have been integrated with bond wrench and triplet tests so as to provide an estimate of the shear force transfer capacity at the base of actual buildings as well as along the boundaries of the connectors’ sockets by adhesion. Results from shake-table testing on a full-scale building mock-up – available at the Experiments platform of the Built Environment Data initiative – demonstrate the accuracy of information and analytical relationship derived here, thus making them applicable in numerical modelling efforts.