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2011
Conference Paper
Titel
Ecological behaviour of mineral mortars and plasters
Abstract
CEN TC 351 WG1 is working on release scenarios for dangerous substances from building materials into the soil and groundwater. Therefore, different laboratory methods for the estimation of substance release are being discussed. In the evaluation scheme proposed by the German Working Group on Water Issues (Bund/Länder Arbeitsgemeinschaft Wasser, LAWA), concentration values are given for organic and inorganic substances, which are considered as non-critical for the groundwater. Results of laboratory leaching experiments are commonly used as input values for this evaluation scheme. The scope of these experiments is focussed on building elements in direct contact with the groundwater. To date no long-time real-climate surveys of irrigated façade materials regarding the leaching of organic and inorganic matter have been published. In a three year experiment, test speciments of mineral plasters and mortars were exposed to real climate conditions. The concentrations of selected organic and inorganic compounds in the run off rain water were measured after nearly each rainfall. Comparing concentrations or release rates measured for a single rainfall with the insignificance threshold values, shows that there is no simple way of evaluating the release behaviour of façade coatings using the values derived from building elements in direct contact with the groundwater. The release mechanisms of façade coatings under real climatic conditions are, due to the intermittent water contact, quite different. Concentrations and release rates determined in the exposition experiment give important about the leaching characteristics of plasters and mortars.