Study of nitrate contaminated samples from a historic building with the hygroscopic moisture content method: Contribution of laboratory data to interpret results practical significance

0480895 - ÚTAM 2019 RIV FR eng J - Journal Article
Nunes, Cristiana Lara - Skružná, Olga - Válek, Jan
Study of nitrate contaminated samples from a historic building with the hygroscopic moisture content method: Contribution of laboratory data to interpret results practical significance.
Journal of Cultural Heritage. Roč. 30, March-April (2018), s. 57-69. ISSN 1296-2074. E-ISSN 1778-3674
R&D Projects: GA MK(CZ) DG16P02H012
Keywords : soluble salts * hygroscopicity * moisture content * nitrate salts * deliquescence * porous building materials
OECD category: Materials engineering
Impact factor: 1.955, year: 2018
https://doi.org/10.1016/j.culher.2017.09.013

The assessment of moisture and soluble salt affecting the masonry materials of a historic building located in Prague triggered the present experimental research focused on the use of the hygroscopic moisture content method for the evaluation of nitrate salts in building materials. The building under study had been recently subjected to a rehabilitation intervention that encompassed the injection of a damp-proofing chemical at the ground level and the application of renovationmortar coats. The applied renovation plasters and renders showed striking moist stains within 6 months after their application. To unveil the reason behind the moist-related problems observed, several samples of repair plasters and renders were collected from affected areas. The HMC method combined with ion chromatography was used to investigate amount of soluble salts. Nitrates were generally found in a high content and located at high levels in the walls. The IC results and the generalised surface wetting observed on-site led us to infer that nitrocalcite was one of the main salts present. The results obtained instigated a laboratory study with the HMC method to assess the hygroscopic behaviour of single nitrate salts and salt mixtures. The selection of single salts and the design of the salt mixtures was based on the IC data of the selected materials’ samples aiming at replicating their hygroscopic behaviour. The results of the case study indicated that the rehabilitation strategy implemented reduced the rising damp phenomena, but that the choice of the type of mortar coats may have contributed to drawing existing moisture to higher levels in the walls. The evaluation of the hygroscopic behaviour of samples with the HMC method at a range of RH provided a better understanding of the on-site behaviour of the salt-contaminated materials in the building. The results of the laboratory study showed that the salt mixtures prepared simulated well the hygroscopic behaviour of the building samples.
Permanent Link: http://hdl.handle.net/11104/0276560