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 (S/S process), 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 teachability. 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 In and Pb were stabilized in the cement matrix even (toxicity characteristic leachiing procedure) at 30% of Fine aggregate replacement with EAFD. From the physico-mechanical and environmental aspects, EAFD can be used as a component in cement mixtures in instances when the In and Pb content is not sufficiently high for justifiable valorization of these metals.