Chromium 6 (Cr6) is an important factor when recycling concrete. Elisabeth Helsing at Rise concludes in a recent article in Bygg & Teknik that the chromium 6 varies depending on:
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lower pH = leaching risk of Cr6 is tenfold when pH decrease from 12.5 to between 8-11
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higher carbonatization (due to porosity/smaller fraction size/aging etc) = increased leaching risk
Ways of decreasing leaching risk could be:
- to use ground granulated blast-furnace slag GGBS in the concrete.
- remove other conatminated materials from the concrete before recycling
- wash the concrete using a wet process
- covering the concrete aggregates under crushed rocks, asphalt or other types of isolation
Further reading:
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Article 2020-11-26 Bygg & Teknik Vad händer med sexvärt krom i återvunnen betong? (print version)
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Report 2019 RISE Krom i krossad återvunnen betong
What other methods do we have to decrease the risk of chromium 6 leaching?