Creep of 45 year old cement paste: the role of structural water

Abstract Microindentation creep and dynamic mechanical thermo-analysis measurements were carried out on compacted specimens of cement paste prepared at water/cement ratios of 1.00, 0.50 and 0.40 and hydrated for 45 years. Similar data was obtained for pastes prepared at w/c = 0.40 and hydrated only 2 months. Creep modulus–mass-loss curves were plotted for all the systems studied. These curves were used to emphasize salient differences between all the paste systems. The influence of degree of hydration, volume concentration of C–S–H, capillary porosity, C–S–H chain-length and the restraining effect of the unhydrated cement particles on creep are parameters that are used to provide a possible explanation for the observation that the creep of the old pastes is higher than creep of the young pastes. The structural role of water in the creep process at various stages of equilibrium drying from the 11 % RH condition is discussed.