Abstract
The disposal or recycling of industrial wastes has been an important and complex issue for the last 20 years. Hydraulic binders have been widely use to treat and/or reuse waste materials. Synthetic wastes are commonly studied but it does eliminate synergistic waste/binder interference effects that can result from real wastes, which are often composed of complex chemical compounds. The objective of this research was to investigate the possibility of reusing waste from the foundry industry. For this purpose, 3 wastes from foundry plants have been selected based on their common metal contaminants. Therefore, the objective of this paper is to investigate the effects of the major metal contaminants, Pb, Zn and Mn, on the mechanical (setting time, unconfined compressive strength (UCS)) microstructural (X-ray diffractometry (XRD)) and leaching characteristics (acid neutralisation capacity test) of the solidified waste materials. The results showed that the addition of the wastes induced a retardation of the setting time, which is believed to be due to the presence of Zn, which is a known retardant. It was also revealed that, at equal water/cement ratio and after 28 days, the UCS of most waste products is within ±10% of the controls. The mineralogical composition, as depicted by the XRD results, was particularly affected as shown by the clear increase of the non-hydrated products. Finally, the addition of the different wastes was shown to have no effect on the buffering capacity of the solidified products.