RECYCLING WASTE IN CEMENT BASED MATERIALS: A STUDYING METHOD

摘要

This paper presents a studying method for the recycling of waste as secondary raw materials in cement-based materials used in civil engineering applications. The approach includes two parts carried out simultaneously: (ⅰ) a technological part, the aim of which is the evaluation of the effect of wastes on the chemical, physical and mechanical properties of fresh and hardened concrete; (ⅱ) an environmental part, mainly based on leaching tests, in order to evaluate the environmental impact of wastes used in concrete materials. When considering the results obtained, associated with past experience and current standards and regulations, two options are possible: either a setting in a controlled landfill, generally following a solidification and stabilisation treatment, or a reuse in building or road works (concrete, road foundations, embankments). This reuse is sometimes preceded by a physical or a chemical treatment, so as to improve the properties of the final product containing the waste material. The method is illustrated with various cases mainly involving by-products from incineration processes i.e. fly ash and bottom ash from municipal solid waste incineration, sewage sludge ash, meat and bone meal ash, bagasse ash (incineration of sugarcane residues). Other by-products, such as titanium fume, river and harbour polluted sediments and spent catalysts from the petroleum industry are also studied.