Hazardous sustanaces emitted from concrete-first study on leaching properties

摘要

Some of the additives used in concrete contain substances regarded as environmentally hazardous. It is therefore relevant to see if these substances will be emitted by leaching, and in that case, under which conditions and at what rate. In an ongoing study, concrete test specimens with different additives were prepared. The additives are fly ash, granulated slag and different admixtures; two AEA's and one accelerator. The aim of the leaching tests is to give answers on the long-term leaching (the availability) and the time dependency. The results will be used to predict the environmental risk caused by hazardous substances in the additives. To predict this risk a model for the transport processes needs to be made. The leaching rates under real conditions could be found by calculating the effective diffusion coefficient. In addition, it is necessary to take into account e.g. the volume of relevant concrete elements, environmental conditions, realistic amounts of additives and the background values of the substances. Preliminary results show clearly detectable concentration levels.