Leaching of Carbon Reinforced Concrete-Part 1: Experimental Investigations

The composite material 'carbon concrete composite (C³)' is currently capturing the building sector as an 'innovative' and 'sustainable' alternative to steel reinforced concrete. In this work, its environmental compatibility was investigated. The focus of this research was the leaching behavior of C³, especially for the application as irrigated façade elements. Laboratory and outdoor exposure tests were run to determine and assess the heavy metal and trace element emissions. In the wake of this work, the validity of laboratory experiments and the transferability to outdoor behavior were investigated. The experimental results show very low releases of environmental harmful substances from carbon concrete composite. Most heavy metal concentrations were in the range of <0.1-8 µg/L, and higher concentrations (up to 32 µg/L) were found for barium, chromium, and copper. Vanadium and zinc concentrations were in the range of 0.1-60 µg/L, boron and nickel concentrations were clearly exceeding 100 µg/L. Most of the high concentrations were found to be a result of the rainfall background concentrations. The material C³ is therefore considered to be environmentally friendly. There is no general correlation between laboratory leaching data and outdoor emissions. The results depend on the examined substance and used method. The prediction and evaluation of the leaching of building elements submitted to rain is therefore challenging. This topic is debated in the second part of this publication.