Hydration characteristics and hydration products of tricalcium silicate doped with a combination of MgO, Al 2O 3 and Fe 2O 3

Abstract

Tricalcium silicate is the major component of ordinary Portland cement and the hydration products are responsible for the high strength of cementitious products. It is known that the crystal structure of tricalcium silicate depends on the kind and amount of foreign oxides incorporated into the lattice. In this study the influence of multiple doping with MgO, Al 2O 3 and Fe 2O 3 on the hydration characteristics was analysed by isothermal heat-conduction calorimetry. The hydration products were characterised by differential scanning calorimetry, X-ray diffraction, 29Si solid-state nuclear magnetic resonance spectroscopy and scanning electron microscopy. The hydration is dominated by the kind and concentration of foreign oxides, independent of the influence of the doped oxide on the crystal structure of C 3S. Combined doping with MgO + Al 2O 3 or MgO + Fe 2O 3 shows no interactions between the foreign oxides on their influence on hydration. In the case of combined doping with Al 2O 3 + Fe 2O 3, the retarding effect of Fe 2O 3 on the main reaction is much stronger in the presence of Al 2O 3.