Release of pollutants from hydrated mixtures of cement and fly ash with a high sulphate and chloride content

Mixtures of cement and fly ash from Municipal Solid Waste (MSW), with a high content of sulphate and chloride as well as a large concentration of heavy metals, were appropriately hydrated. In the leaching test using deionised water, these mixtures showed an efficient interaction of the sulphate with the cementitious matrix. The behaviour of chloride release from pastes hardened has shown that an acceleration of the hydration process takes place. This acceleration was particularly intense for the mixtures with an intermediate fly ash content. The release of polluting elements as Cu, Zn, Cd, Pb, Cr(VI) from the solidified mixtures was correlated to the degree of stabilisation of the fly ash.