Validation of a leaching test for release from building products

All building products which come into contact with groundwater, rain or seepage water must be able to provide proof of their safety for the sake of the protection of soil and groundwater. Reliable test methods are necessary. These methods must be “horizontal“, or suitable for application to many different product groups, to ensure the comparability of different building products.

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Information on leaching behaviour to become standard information on building products

Users of building products do not yet have any information about the pollutant emissions or contents of a given building product. This is about to change. As a result of current efforts to harmonise the evaluation of emissions from building products in the EU, architects, construction firms and craftsmen will soon see that CE marking includes information like “Leaching of hazardous substances: Class I“. Years of European standardization work will have gone into that simple declaration.


New test standards require validation

In 2005 the European Commission requested the European Committee for Standardization (CEN) to develop methods to assess hazardous substances under the Construction Products Regulation. The main outcome of standardization work in recent years has been a number of test standards, which are currently being validated in round robin tests. Once they have been validated the harmonised methods can provide reliable measurement results for CE marking.

A Federal Environment Agency research project (see “Publications”) carried out by the central organisation of the German cement industry (VDZ) and the Institute of Building Materials Research at the RWTH Aachen University conducted validation tests for the new European “Generic horizontal dynamic surface leaching test (DSLT) for determination of surface dependent release of substances from monolithic or plate-like or sheet-like construction products” on cements and mortars. The tests demonstrated how varying test conditions (e.g. test temperature or ratio of eluent volume to surface area of test specimen) can affect results and constancy of results when the tests were repeated. Robustness testing confirmed that the leaching test is robust. No changes to the European draft standard were required as concerns the admissible range of test conditions.

The figure below illustrates the cumulated leaching amounts of TOC (total organic carbon) for all mortar tests. The very good correlation of the test results under the various test conditions shows that the examined test method is appropriate for testing the leaching of organic substances besides the release of inorganic substances from construction products. This will prove a great advantage in practice for it will help manufacturers to optimise the formula of their products by using only one leaching behaviour test.

Diagramm: TOC release of reinforcement plaster is rising to ca. 5,000 to 6,000 mg /m² after ca. 35 days, according to different test conditions
TOC release of reinforcement plaster under varying test conditions
Source: Umweltbundesamt diagram and legend as PDF file

Reliable information on release of hazardous substances soon to be state of the art

The application of the new method is recommended as soon as it is approved as a technical specification (CEN/TS 16637-2): both in a legal context under the new EU Regulation laying down harmonised conditions for the marketing of construction products ((EU) No 305/2011), as well as for voluntary labelling and environmental product declarations. The new method offers a solid foundation on which to establish the safety of construction products for soil and bodies of water and to implement the environmental protection requirements posed under the Construction Products Regulation and corresponding national building law.