Study of Cement Paste Setting at Microstructural Level

Synopsis: In this study, various fresh cement paste microstructure evolutions were observed during setting in a conventional SEM by employing a new sample technique called Quantomix capsuling system. Individual cement particle and different phases growths were studied quantitatively by using image analysis techniques on observed micrographs. The ASTM C191 method was used to determine the cement pastes setting times and further the developments of different phases in the cement pastes microstructure were studied at various stages of setting. It was observed that irrespective of the water to cement (w/c) ratio, cement particle connectivity plays a major role in Vicat needle settlement (or in cement paste setting); however, it was observed that w/c ratio influences the hydration rate in mixtures. It was also observed that during setting water phase depletion wholly depends on richness of the mixture, whereas solid phase growth is a combined effect of cement particle growth and connectivity.