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. The hydration behaviour was studied using FTIR, TGA/DTA and SEM. The cements with EAFS had a higher C2S/C3S and C4AF/C3A ratio compared to the reference body and as a result the rate of hydration was low initially whereas the structure was porous with scattered AFm and C-S-H crystals. After 28 days, a comparable dense microstructure consisting largely of C-S-H was observed in all the mortars. Leaching of V and Cr was studied using a tank test according to standard NEN 7345. The results showed V release < 2 microg/l. Chromium release calculated per 24 h was 1.4 microg/l in BC5 and 2.4 microg/l in BC10, which was much lower than the parametric value of 50 microg/l specified by the European directive for drinking water (98/83/EC).