Leaching behaviour of mortars and renders - laboratory experiments vs. real climate exposition

There are two European standards describing test methods for the evaluation of the leaching properties and the environmental impact of construction materials in contact with water. CEN/TS 16637-2 is a harmonised horizontal testing method developed by CEN/TC 351 WG1 derived from a Dutch standard and a German guideline for concrete in permanent contact with groundwater, a so-called dynamic surface leaching test. During this 64-day test a specimen is stored under water. The water is replaced for eight times and the samples are not allowed to dry during this procedure. The test according EN 16105 is derived from a procedure for wood preservatives. It is deemed to be a test method suitable to evaluate the leaching behaviour of renders like façade coatings in intermittent contact with water within three weeks. Depending on the analytes and on the mortar or render types the findings of both laboratory experiments are quite different. So up to now it is not possible to decide which laboratory test reflects better the behaviour of the renders under real climate conditions. Therefore a large number of mineral and organic renders were exposed to the real climate and also subjected to both standardised tests. A set of sum parameters and compounds were analysed to get a first overview of the substance release under different experimental and realistic conditions. Compound concentrations in the leachates and the runoff are compared.