Fractographic studies of microstructural development in hydrated Portland cement

A comprehensive study of early hydration and morphological development in freeze-dried Portland cement paste has been carried out using scanning electron microscopy in conjunction with energy dispersive x-ray analysis. The microstructure develops from its early appearance as a porous C - S - H spherulite structure containing hexagonal CH crystals, with Hadley grains and large inherent pores being significant features, to one of large CH dispersions in massive C - S - H. Some aspects of microstructural influence on mechanical properties are discussed.