Early Age Hydration, Microstructure and Micromechanical Properties of Cement Paste Modified with Polymeric Vesicles

摘要

The influence of limited concentration, of 0.025 wt.% per cement weight, poly (ethylene oxide) -block -polystyrene vesicles on the hydration process, microstructure and micromechanical properties of cement paste at early hydration age of maximum 7 days are discussed. Isothermal calorimetry and non-evaporable water content tests indicate that the admixed vesicles have no apparent influence on the process of cement hydration, but affect microstructural properties. Whereas nitrogen adsorption tests reveal that the gel pore structure of the vesicles-modified matrix is almost identical to the vesicles-free one, mercury intrusion porosimetry proves refined capillary porosity and reduced total porosity in the presence of admixed vesicles. Nano-indentation supports the above observations and indicates that the admixed vesicles act as nucleation sites, leading to a more uniform distribution of low density hydration products.