In Italian buildings, especially dwellings, walls are very often plastered with gypsum plaster for levelling purposes. The gypsum plaster is generally covered with waterborne wall paint for decoration which represents a barrier for the water absorption or desorption. To know the hygric performance of a room in such real conditions, the water transfer properties of the Painted gypsum must be known. Wall paints can be roughly divided into waterborne and solvent borne paints. Waterborne wall paints are increasingly being used for their low odour and fast environmental friendly drying. The newer waterborne paints are based on aqueous dispersions of synthetic vinyl-type binders, such as polyvinylacetate or polyvinylpropionate (co-)polymers, and acrylic polymers. Moreover, paints containing volatile organic components have recently been prohibited by the European Commission for professional indoor use. The pressure to reduce volatile organic components and the industrial trend towards friendlier products with low toxicity of the product formulation led to the current expansion of waterborne types of coating. In building physics literature, knowledge is lacking about the moisture transfer properties of waterborne wall paints. Also the behavior of painted substrates has not been examined sufficiently. The role of the paint constituents in the moisture transfer properties is unclear. This lack of knowledge is partly caused by the lack of simple measuring techniques. Also the moisture behavior of the gypsum plays an important role in controlling the relative humidity, as the experimental activity in the paper for measuring its hygroscopic properties (Moisture Buffer Value) highlights. Painting gypsum is not done to prevent deterioration of the substrate as usually done for wood; gypsum is mainly painted for decorative reasons: this can also be a means to control the moisture transfer properties of the gypsum. Anyway, aim of the present study is not the numerical modelling or measuring of waterborne paints, but their influence once applied to the gypsum substrate, of which the hygroscopic properties where calculated when coated and uncoated. The numerical simulation using an whole building HAM-transfer model is then used to simulate the hygroscopic performance of a room in different conditions.
|Titolo:||The influence of coatings on the environmental hygric inertia of plastered rooms|
|Data di pubblicazione:||2015|
|Digital Object Identifier (DOI):||10.1016/j.egypro.2015.11.178|
|Appare nelle tipologie:||1.1 Articolo in rivista|