Hydration of alinite cement produced from soda waste sludge

Alinite cement is an alternative inorganic, low-energy binding material. This experimental study investigated hydration characteristics of alinite cement which was produced by using soda waste sludge as a raw material. Paste microstructures were studied by X-ray powder diffraction and scanning electron microscopy. Heat of hydration and compressive strength values were also determined. Formation of C-S-H gel and calcium chloroaluminate hydrates which resemble Friedel's salt was observed. Induction period of alinite cement was around 15-20 min and unlike Portland cement, hydration did not practically stop during this period. Up to 12% gypsum addition to alinite cement resulted in increased compressive strength.