Evaluation of asphalt cleaning water with the aid of biotests

Semi-dense asphalts are increasingly being used as road surfaces in Switzerland, as they reduce noise due to their structure (cavity content). The voids become clogged over time and the asphalt loses its acoustic effect. In order to slow down this acoustic ageing, individual system owners have opted for high-pressure cleaning with water. To improve cleaning efficiency, alternative cleaning methods have been tested at laboratory level, but it is not clear whether these have a negative impact on the toxicity of the wash water. To find out, the Ecotox Centre is investigating the wash water from asphalt samples using bioassays. It is applying a protocol that was used in earlier projects to analyse leachate from building materials and has been adapted by the German Institute for Building Technology (DIBt).

Biotests used

• Luminescent bacteria test for general toxicity
• Combined algae test: effects on photosynthesis and growth
• Chronic reproduction test with water fleas
• umuC test: determination of genotoxicity

Photo: Peter Mikhailenko