PhD thesis by Anne Mette T. Simonsen
The purpose of the research project is to determine and categorize critical mine waste characteristics for valorization as constituent in concrete with focus on the mechanical and environmental performance of the concrete.
Cement production is responsible for minimum 5 % of the global anthropogenic CO2-emission. Partial replacement by materials that contribute less CO2-emission thus has potential to significantly reduce climate impact of the construction industry. As cement production amounts to just above 4 billion tons annually, even partial replacement, however, requires large volumes of suitable material.
Almost 200 billion tons of mine tailings are produced annually. Mine tailings originate from the processing of metal and mineral ores and represent one of the largest waste streams. The processing generates a fine-grained slurry fine mineral particles, process water, chemicals and elevated concentrations of heavy metals. The deposition of mine tailings into on-land storage facilities or under water can cause severe environmental impacts especially due to the large volumes generated and the release of toxic heavy metals from the waste product.
As an alternative to deposition, mine tailings have shown potential to be used in construction materials especially as partial replacement of the binder material in concrete. The research on mine tailings join research fields of concrete technology, material science, environmental risk analyses, remediation technologies and statistical methods. The interdisciplinary research fields enable a thorough assessment of the usability of mine tailings as cement replacement in concrete.