Immobilization of Electric Arc Furnace dust toxic elements within the matrix of concrete based products

Electric Arc Furnace Dust (EAFD) generated through the production of carbon and alloy steel products
is classified as environmentally hazardous waste mainly because of its relatively high levels of Pb, Cd
and Cr. The aim of the present work was to investigate the effect of the EAFD addition on the properties
of concrete building products (e.g concrete bricks) and to stabilize the toxic elements contained in
EAFD in order to get environmentally accepted products. Concrete specimens were prepared by vibration
and press-forming of mixtures containing cement, sand, dolomite, calcium stearate with water and the
addition of different percentages of EAFD. For the immobilization of the toxic elements of EAFD within the
matrix of the specimens, different percentages of each one of NaH2PO4, H3PO4 and of a mixture of H3PO4
- FeSO4.7H2O were added successively to each one of the mixtures as stabilizing materials. Modulus of
rupture (MOR) and water absorption (WA) tests showed that the specimens produced had specifications
within accepted limits for relevant products. Leaching tests applied on the specimens proved the compliance
with imposed leachate Maximum Acceptable Limits (MAL), since the practiced stabilizing materials
effectively immobilize toxic elements within the prepared specimens.