Abstract
Hydrophobization lessens the water absorption by facade materials and is thus presumed to reduce moisture problems in internally insulated facades. However, to do this it should retain the water repellency performance throughout aging. The aim of this study is to evaluate the impact of aging on the durability of the hydrophobic treatment on bricks and mortars. The resulting absorption coefficient, after 635 repeating artificial aging cycles of alternating UV radiation (102 min) and water exposure (18 min) reveals that the hydrophobic layer maintains its water repellency performance both in brick and mortar. The samples were treated with two different water repellent agents in different concentrations and tested for capillary water uptake. Additionally, the findings show that cycles of weathering could contribute positively to further reduction of the absorption coefficient of hydrophobized brick and mortar samples. Subsequently, Karsten tube tests on samples from artificial aging illustrate the same water repellency performance as mock-up walls exposed to ambient conditions, six years after being hydrophobized. Contact angle measurements before and after artificial aging reveal that the beading effect declines through aging. However, the beading effect seems to be just a surface effect affected by UV-light. Moreover, after aging, hydrophobized brick and mortar samples, tested by visual inspection, maintain their appearance while untreated samples show signs of efflorescence. In total, these findings indicate that the water uptake of hydrophobized brick or mortar remains very low after aging including water spraying and UV light.
Highlights
Denmark is targeting to be independent of fossil fuels by the year 2050 [1]
Karsten tube tests on samples from artificial aging illustrate the same water repellency performance as mock-up walls exposed to ambient conditions, six years after being hydrophobized
Contact angle measurements before and after artificial aging reveal that the beading effect declines through aging
Summary
Denmark is targeting to be independent of fossil fuels by the year 2050 [1]. In the EU, existing buildings represent 99% of the building stock [2], which accounts for about 40% of the total energy consumption [3]. 10%–40% of these buildings [4] are historical, high energy-consuming buildings [3,5,6,7]. The household’s energy con sumption within EU-27 is dominated by space heating in a percentage of 67% [8] Often such buildings have worth preserving solid facades, making internal insulation the only feasible technique for thermal insulation [9]. Concrete impregnated with a water repellent agent in cream form illustrates resistance against salt formation [32] but there are no similar studies for brick and mortar Each of these factors highlights the need to investigate the durability of hydrophobized masonry and prior to that, the durability of masonry components, i.e. hydrophobized brick and mortar samples, expressed by the absorption coefficient, as well as the appearance of the hydro phobized materials after aging. Even though contact angle measurement is not a precise indicator to assess the water repellency performance [33], comparing the contact angle in hydrophobized ma terials before and after artificial aging could provide information on the influence of the aging on the beading effect
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