This study investigated the effects of ageing on the physical and chemical properties of six stabilised/solidified materials. The materials were analysed to determine their total chemical content and subjected to the NRA leaching test method. Analysis of the leachate showed metals Cd, Hg, Ni, and Zn were effectively immobilised, as were low concentrations of hydrocarbons. Metal contaminants Al, Cr, Pb and organic contaminants phenols and TPAHs leached from one or more of the treated materials. Comparison of the leachate data with environmental quality standards and published dilution factors, showed four stabilised/solidified materials posed no threat to a water resource. Other findings from this study showed that contamination controlled the early strengths of all six materials and the long term strength of two materials. A crushed stabilised/solidified material met the physical and environmental specifications required for earthwork Class 1 and 6 materials, aggregate in a cement bound material and Type 1 sub-base road construction materials. The lack of testing of aged stabilised/solidified materials produced by commercial processes, has been highlighted by previous research. This study has shown that the physical and environmental properties of several stabilised/solidified materials improved with age. (A)

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