The purpose of this study is to utilize an electroplating sludge for belite-rich clinker production and to observe the influence of heavy metals on the polymorphs of dicalcium silicate (C2S). Belite-rich clinkers prepared with 0.5-2% of NiO, ZnO, CuO, and Cr2O3 were used to investigate the individual effects of the heavy metals in question. The Reference Intensity Ratio (RIR) method was employed to determine the weight fractions of gamma-C2S and beta-C2S in the clinkers, and their microstructures were examined by the transmission electron microscopy (TEM). The results showed that nickel,zinc, and chromium have positive effects on beta-C2S stabilization (Cr3+ > Ni2+ > Zn2+), whereas copper has a negative effect. The addition of up to 10% electroplating sludge did not have any negative influence on the formation Of C2S. It was observed that gamma-C2S decreased while beta-C2S increased with a rise in the addition of the electroplating sludge. Moreover, nickel and chromium mainly contributed to stabilizing beta-C2S in the belite-rich clinkers produced from the electroplating sludge. (C) 2009 Elsevier B.V. All rights reserved.