Fred P. Glasser

Chloride ingress in cement paste and mortar

In this paper chloride ingress in cement paste and mortar is followed by electron probe microanalysis. The influence of several paste and exposure parameters on chloride ingress are examined (e.g., water-cement ratio, silica fume addition, exposure time, and temperature). The measurements are modelled on Ficks law modified by a term for chloride binding. Inclusion of chloride binding significantly improves the profile shape of the modelled ingress profiles. The presence of fine aggregate and formation of interfacial transition zones at paste-aggregate boundaries does not significantly affect diffusion rates.

Clinker mineral hydration at reduced relative humidities

Abstract Vapour phase hydration of pure cement clinker minerals at reduced relative humidities is described. This is relevant to modern high performance concrete that may self-desiccate during hydration and is also relevant to the quality of the cement during storage. Both theoretical considerations and experimental data are presented showing that C 3 A can hydrate at lower humidities than either C 3 S or C 2 S. It is suggested that the initiation of hydration during exposure to water vapour is nucleation controlled. When C 3 A hydrates at low humidity, the characteristic hydration product is C 3 AH 6 , hydrogarnet.