The Mechanism of Synergistic Hydration of C3s-C4af and the Micromechanical Properties of its Hydration Products

The effects of C4AF on the hydration reaction rate of C3S and the phase and micromechanical properties of the synergistic hydration products are evaluated through isothermal calorimetry, XRD, TGA, and 27Al and 29Si magic-angle spinning NMR spectroscopy. The accelerated hydration reaction of C4AF and its participation in the formation of an extragranular hydration reaction coating of C3S delays the early hydration reaction of C3S. C4AF enhances the hydration response of mid-late C3S at the end of the induction period. The growth of the hydration product of C4AF is inhibited, which decreases its hydration rate. The deconvolution results of the nanoindentation test data indicate that the doping of the disordered phase C-(A,F)-H increases the mean elastic modulus and volume fraction of the low-density calcium-silicate-hydrate phase. The hydration mechanism of C3S-C4AF and micromechanical properties of the products can be used to explain the evolution of the mechanical properties of high-ferrite Portland cement.