Microindentation creep of secondary hydrated cement phases and C–S–H

Microindentation creep measurements were obtained on compacted specimens of several secondary hydrated cement phases in equilibrium with water vapor at 11%RH. Values of creep modulus, indentation modulus and indentation hardness for calcium hydroxide, ettringite, gypsum and calcium carbonate are reported. The porosity dependence of these parameters was established and the significance of porosity on the time-dependent deformation of these materials was discussed. In addition the microindentation creep behavior of pure C–S–H and C3S paste hydrated 32 years was determined. The discussion focuses on the relative importance of the contribution of the secondary phases in hydrated cement-based materials to creep with respect to the more ‘active’ C–S–H phase.