The interaction between concrete pavement and corrosion-induced copper runoff from buildings

Abstract

Changes in chemical speciation of copper and the capacity of concrete pavement to retain copper in runoff water from external buildings have been investigated at urban field conditions, and in parallel laboratory experiments simulating outdoor scenarios. The research study showed the concrete surface to form a copper rich surface layer ( approximately 50 microm thick) upon exposure, and a high capacity to significantly reduce the bioavailable fraction of released copper (20-95%). The retention capacity of copper varied between 5 and 20% during single runoff events in the laboratory, and between 10 and 40% of the total copper release during single natural runoff events. The capacity to retain and reduce the bioavailable fraction of non-retained copper increased with increasing wetness of the concrete surfaces, increasing pH of the runoff water and decreasing flow rates. Bioassay testing with bacterial and yeast bioreporters showed the bioavailable fraction of non-retained copper to be significantly lower than the total copper concentration in the runoff water, between 22 and 40% for bacteria and between 8 and 31% for yeast. The application of generated data to simulate a fictive outdoor scenario, suggests a significant reduction of bioavailable and total copper to background values during environmental entry as a result of dilution, and the interaction with solid surfaces, organic matter and complexing agents already in the drainage system.

Long-term use of galvanized steel in external applications. Aspects of patina formation, zinc runoff, barrier properties of surface treatments, and coatings and environmental fate

“…1), and the capacity of pavement slabs of concrete to retain zinc was investigated. The study clearly illustrates, as in the case for copper investigated in a more thorough and detailed investigation (Bahar et al 2008), that already with a contact length between the runoff water and the concrete surface of approximately 1 m, zinc ions were retained by the concrete surface. Depending on rain intensities (flow rates) and length of dry conditions preceding the rain event, between 7% and 25% of zinc in the runoff water was retained by the concrete surface at laboratory conditions (Fig.…”

“…Considering dilution effects and changes in chemical speciation and interaction with other solid surfaces, an even faster retention is anticipated. These results imply, as in the case proven for copper runoff from roofs (Bahar et al 2008;Odnevall Wallinder et al 2009), that a large portion of zinc released from outdoor constructions induced by corrosion actually is retained by solid surfaces already in the near vicinity of a building.…”

“…To obtain a constant flow direction and to simulate a realistic scenario, the concrete slabs were inclined 2 • from the horizontal according to the Swedish standard building specifications (Swedish Building Standards 1984). Details for the experimental setup are given elsewhere (Bahar et al 2008). Artificial runoff water was prepared by mixing artificial rain water of pH 4.3, pH-adjusted to 6.2 using NaOH and ZnCl 2 to reach a total zinc concentration of 4.2 mg L −1 , a median value for roof runoff water from zinc sheet (Bertling et al 2002).…”

“…Artificial runoff water was prepared by mixing artificial rain water of pH 4.3, pH-adjusted to 6.2 using NaOH and ZnCl 2 to reach a total zinc concentration of 4.2 mg L −1 , a median value for roof runoff water from zinc sheet (Bertling et al 2002). Additional information is given in Bahar et al (2008).…”

Misapplication of generic hazard-classification schemes for versatile, sustainable building materials: Copper as an example

“…For example, 45% of the copper in a roof runoff water was removed as it flowed through a 57.9-m cast-iron-and-concrete internal piping network (Boulanger and Nikolaidis 2003). Likewise, copper can precipitate onto concrete slabs (e.g., sidewalks) and other surfaces as copper carbonate, copper hydroxide, or copper sulfate minerals, thus removing considerable percentages of the total copper released from copper roofing during runoff events (Liu et al 2005;Bahar et al 2008;Sondhi 2010). Additionally, soils and retention-basin sediments can retain copper as runoff water flows through them (Nightingale 1987b;Wilde 1994;Bertling et al 2006), making commonly installed stormwater management features such as retention ponds, bioretention planter boxes, biofiltration swales, and lawns effective sinks for copper (>90%) and other metals (Davis et al 2001(Davis et al , 2003LaBarre 2014;LaBarre et al 2016).…”