Ceramics-Silikáty 57 (2) 126-132 (2013)

HYDRAULIC AND LEACHING BEHAVIOUR OF BELITE CEMENTS PRODUCED WITH ELECTRIC ARC FURNACE STEEL SLAG AS RAW MATERIAL

Three belite-rich cements consisting of a clinker made with 0 (BC), 5 (BC5) and 10 wt. % (BC10) electric arc furnace steel slag (EAFS) as raw material, were studied for their hydraulic and leaching behaviour. Hydration behaviour was studied by FTIR, TG/DTG and SEM analyses. The cements with EAFS resulted in a higher C₂S/C₃S and C₄AF/C₃A ratio compared to the reference body. As a result, the rate of hydration was low at early days whereas the structure was porous with scattered AFm and C–S–H crystals. At 28 days, a comparable dense microstructure consisting largely of C–S–H is observed in all mortars. Leaching was studied for V and Cr by means of tank test according to standard NEN 7345. The results showed V release below 2 μg/l. Chromium release calculated per 24 h was 1.4 μg/l in BC5 and 2.4 μg/l in BC10, which is much lower than the parametric value of 50 μg/l specified by the European Directive for drinking water (98/83/EC).

Keywords: Belite cement, Electric arc furnace steel slag, Raw material, Hydration, Leaching