Investigation of capillary rise in brick masonry models under controlled conditions

Capillary rise is a well-known decay factor of brick masonries and many studies focus on its evaluation. A comprehensive monitoring methodology to assess damp distribution in complex masonry structures in known conditions is still lacking. This study investigates the capillary rise process in brick masonry on several different experimental setups. Thirteen brick-grout mock-up walls were constructed with commercial or historical full bricks embedded in natural hydraulic lime or lime mortars. Some walls were rendered with traditional lime or hydraulic lime plasters to evaluate the behavior of both non-rendered and rendered masonries. The properties of each stand-alone material were characterized by including porosity, water absorption and permeability assessment. Instead, the mock-up walls were subjected to controlled rising damp conditions. Non-invasive and continuous monitoring methods, including visual assessments, capacitance probes, and electrical sensors were employed to measure moisture distribution over one year, while moisture content was assessed on brick samples drilled after one year. Additionally, experimental data were loaded into WUFI 2D hygrothermal simulation software to model rising damp behaviour. Comparison of the various methods of assessing the moisture distribution within the walls shows that non-invasive measurements allow extensive and repeated monitoring of the surface and, overall, provide information consistent with that assessed by the gravimetric method on drilled samples or by continuous electrical measurement. The results highlight the critical role of brick surfaces in evaporation, the effect of bedding mortars in hindering or not the rising damp process, and the influence of render layers. Furthermore, digital modeling demonstrated its capabilities in simulating rising damp in complex masonry structures.