Possibility of carbon steel eafd solidification/stabilization in concrete

Abstract

Steel scrap recycling is generally performed by direct smelting of scrap in an electric arc furnace, generating about 2% of dust per charge. Electric arc furnace dust (EAFD) is characterized as a hazardous material, due to its heavy metals content and a powder form. A present study indicates the possibility of domestic carbon steel EAFD stabilization by using cement as the main stabilizer; fly ash as an additive, and controlling the EAFD particle size by milling. EAFD replaced 0-50 % of fine aggregate and fly ash replaced 10-25% of cement in mixtures, with different milling times applied. S/S samples were tested for compressive strength and heavy metals leachability. The results of compressive strength testing showed that the maximum EAFD replacement is 15%, after which compressive strength decreases rapidly. The best fly ash compressive strength was attained at 10% replacement of both fine aggregate and cement. The milled EAFD produced the best results at three hours of milling, however, the addition of fly ash resulted in a slight compressive strength decrease in these samples. The TCLP analysis of concrete samples indicated that Zn and Pb were stabilized in the cement matrix even at 30% of fine aggregate replacement with EAFD. From the physical-mechanical and environmental aspects, EAFD can be used as a component in cement Mixtures in instances when the Zn and Pb content is not sufficiently high for justifiable valorization of these metals.