ABSTRACT
In spite of the intensive research of the last fifty years, the hydration process of pure Portland cement-based concrete is not clear. Then, one cannot expect to understand the mechanism or mechanisms involved in the hydration process of the binder which often consists of mineral admixtures; fly ash, blast furnace slag, silica fume, rice husk ash etc., and chemical admixtures; water reducers, air entraining agents etc. These interact both physically and chemically during the hydration process. The microstructure depends very much upon the behaviour of these constituents, which control the properties of concrete.
