Effect of CuO-doping on the hydration mechanism and the chloride-binding capacity of C4AF and high ferrite Portland clinker

Ongoing marine development has drawn considerable attentions on reinforcing the construction of marine engineering. A high ferrite Portland clinker (HFPC) with 47% C3S, 27% C2S, 6% C3A, and 20% C4AF was designed in this study. Compared with traditional Portland cement, there is larger amount of C4AF and hydration products like AH3 and FH3 that can absorb Cl−, SO42−, Mg2+ from seawater in the high ferrite cement. The activities of C4AF and C3S could be changed by adding Cu2+ under first-Principle calculation. The hydration activity of the high ferrite Portland clinker (HFPC) can be significantly enhanced by doping with Cu2+ because Cu2+ solidifies better in C4AF. This study aims to explore the mechanism of CuO-doping on the hydration performance and chloride-binding capacity of HFPC by using different microscopic analysis methods, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and nuclear magnetic resonance (NMR). The results show that C4AF has the better hydration activity when it is incorporated with 1.0% CuO. According to our calculations by Density Functional Theory and our experimental results, C4AF was easily influenced by the doping Cu2+. As for C4AF, the site of ferrite element can be replaced by copper element, accounting for the improvement of the hydration activity of it when the moderate amount of CuO was doped. As for C3S, it had the less influence of CuO-doping on it when few amounts of CuO was doped into the clinker. The polymorph of C3S was transferred from R to MIII, when the CuO amount was up to 0.8% which made a has unsatisfactory hydration activity under this condition. Taking all the results into consideration, HFPC has the better hydration activity and chloride-binding capacity when 0.2%CuO is doped into the clinker.