SEM image of cement clinker

The image shows a Scanning Electron Microscope (SEM) image of a cement clinker particle. The image was taken with a SEMQuant Scanning Electron Microscope at the Physics Department of Aristotle University Thessaloniki, Greece. In the manufacture of Portland cement, clinker is the solid material produced in the cement kiln stage by heating the rawmix in oxidising conditions to around 1400-1450°C, at which temperature partial melting (sintering) takes place, producing hard spherical nodules around 5-20 mm in diameter. These are rapidly cooled to preserve their reactive mineral constituents. The clinker is primarily composed of tricalcium silicate (alite), dicalcium silicate (belite), tricalcium aluminate (3CaO.Al2O3), and calcium aluminoferrite (2CaO.(Al,Fe)2O3). The major raw material for making clinker is usually limestone(CaCO3):