Preparation of beta-dicalcium silicate (beta-C2S) and calcium sulfoaluminate (C(3)A(3)(CS)over-bar) phases using non-traditional nano-materials

This paper describes the synthesis of some nano-compounds such as SiO2, Al(OH)(3), Ca(NO3)(2) and gypsum which can be used in the preparation of nano-beta-C2S as well as nano-C(3)A(3)(CS) over bar. The preparation of beta-C2S from nano-SiO2 and Ca(NO3)(2) in comparison with traditional materials such as Ca(CH3COO)(2), CaCO3 and silica quartz fired at different temperatures has been studied. Also, C(3)A(3)(CS) over bar, can be prepared from nano-materials such as Ca(NO3)(2) and Al(OH)(3) with pure gypsum in comparison with Ca(CH3COO)(2), CaCO3 and calcined Al2O3. The rate of formation of beta-C2S and C(3)A(3)(CS) over bar, can be also studied after firing with chemical and XRD methods. These phases were obtained by crystallization processing at differenr temperatures. The formation of these phases were monitored by measuring the free lime and insoluble residue contents as well as with the aid of XRD technique. The results showed that the extent of formation was found to be much higher with nano-materials as compared to those prepared in a conventional manner. The prepared belite phase with nano-silica and calcium nitrate reduces the temperature synthesis to 1150 degrees C. Also the preparation of C(3)A(3)(CS) over bar from nano-Al(OH)(3) and Ca(NO3)(2) and pure gypsum fired at 1290 degrees C, was the perfect composition to produce a well formed calcium sulfoaluminate phase i.n comparison with traditional materials. (C) 2012 Elsevier Ltd. All rights reserved.