Masonry brick–cement mortar interface resistance to water transport determined with neutron radiography and numerical modeling

Masonry is one of the most common building envelope systems in the world, providing an excellent water protection solution against rain. Water transport in masonry walls composed of bricks and mortar joints can be strongly affected by the nature of the interface between brick and mortar. In this study, two-dimensional water uptake experiments and numerical simulations are performed to study the effect of interface resistance on moisture transport in masonry samples with horizontal and vertical interfaces. Neutron radiography is used to document the time- and space-resolved moisture content distribution in different masonry samples. In the simulation of moisture transport, an interface resistance models the imperfect contact between brick and mortar. A good agreement between measured and simulated moisture content distribution is observed for different masonry samples. Moisture transport in masonry could be strongly affected by the interface resistance, when interface is in proximity to moisture source. The orientation, horizontal or vertical, of the interface between brick and mortar does not have an influence on the value of the interface resistance. However, the interface resistance depends on the capillary pressure at the interface. In the range of capillary moisture transport, a lower capillary pressure at the interface will lead to a larger interface resistance.