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ECN publication
Mogelijkheden tot verbetering van de voorspellende waarde van laboratorium-uitloogproeven voor de praktijk (ANVM 228)
Sloot, H.A. van der; Rietra, R.P.J.J.; Mulder, E.; Hage, J.L.T.; Brouwer, J.P.
Published by: Publication date:
ECN 1-11-2001
ECN report number: Document type:
ECN-C--01-027 ECN publication
Number of pages: Full text:
72 Download PDF  

Subject of this study is an investigation for improvement of the relationship between laboratory leaching tests and observations in the field. Via a desk study the need to improve, differentiate, and/or adapt laboratory tests is addressed in order to improve the agreement between predictions based on laboratory tests and the real exposure of materials.For such a study one would ideally use the results of Iaboratory, lysimeter and field investigation from one project. However these results are not available for most materials and therefore certain generic processes are identified that determine the differences between leaching from materials in laboratory and leaching in field conditions. Important differences between leaching in laboratory and field conditions are the preconditioning of materials in laboratories such as grinding to a certain particle size, and the differences of environmental factors that can have a large influence on the leaching: pH and redox conditions. Differences between the pH in the laboratory test and in the field are due to carbonatation by CO2 from air or from the degradation of organic material (relevant for bottom ash, slags, cement stablised materials). Differences in pH in laboratory and the field can also be due to release of alkaline material after grinding of material in laboratory conditions (relevant for bottom ash and slags). Differences between the redox in laboratory test and in the field can be due to grinding of materials (relevant for slags). Differences between redox in laboratory and field conditions can be caused by application of material in reducing environmental conditions in sediments or in confined applications. The observed differences between the environmental conditions in the laboratory tests and the field do not have the same effect on the leaching of components and in many cases a good agreement has been established between leaching in the laboratory test and in the field. For a range of components the differences between the leaching in the laboratory test and in the field are significant and can lead to a different classification in the Dutch regulations for building materials (Building Materials Decree). There are technical possibilities to decrease the differences between the leaching conditions in the laboratory test and in the field. It is recommended to have at least a full characterization for each type building- and Waste material: leaching as a function of pH, acid-neutralising capacity, reducing capacity, columntest and diffusiontest. This enables one to determine the effect of the critical parameters on leaching and to assess if leaching in the lab can be strongly different from leaching in the field. It is also recommended to assess the leaching from materials that have been exposed in field conditions for a long time to determine the neoformation of minerals. For several materials improvements of the laboratory tests are suggested on the basis of the material applications. The suggested improvements are classified depending on the required research and according to their potential to be incorporated in legislation on the short term or long term.

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