The aim of the paper was to determine values concerning elution of selected heavy metals from the C16/20 ordinary concretes containing fly ashes which had been produced in thermal conversion of sludge and constitute 15% of the calculated cement amount. The concrete samples were comminuted into two fractions – with graining under 4 mm and under 1 mm – which were subjected to elution and then the content of Cd, Cr, Cu, Ni, Pb, Zn, As, Sb and Se in the resulting eluat was assayed. The heavy metal contents which have been determined are considerably lower than the maximum values defined in the directives which must be fulfilled during introduction of sewages to water or soil – i.a. the directives on the substances which are particularly harmful for the water environment and on elution limit values required for wastes to pass them as fit for storage on dumps. It has been stated on these grounds that the migration of heavy metals from concretes with admixture of fly-ashes is negligible and probably does not present problems. However, the investigations require to be continued for various classes and types of concrete and for diversified conditions of elution.

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