Preparation of β-dicalcium silicate (β-C_2S) and calcium sulfoaluminate (C_3A_3CS) phases using non-traditional nano-materials

摘要

This paper describes the synthesis of some nano-compounds such as SiO_2, Al(OH)_3, Ca(NO_3)_2 and gypsum which can be used in the preparation of nano-β-C_2S as well as nano-C_3A_3CS. The preparation of β-C_2S from nano-SiO_2 and Ca(NO_3)_2 in comparison with traditional materials such as Ca(CH_3COO)_2, CaCO_3 and silica quartz fired at different temperatures has been studied. Also, C_3A_3CS, can be prepared from nano-materials such as Ca(NO_3)_2 and Al(OH)_3 with pure gypsum in comparison with Ca(CH_3COO)_2, CaCO_3 and calcined Al_2O_3. The rate of formation of β-C_2S and C_3A_3CS, can be also studied after firing with chemical and XRD methods. These phases were obtained by crystallization processing at different 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 ℃. Also the preparation of C_3A_3CS from nano-Al(OH)_3 and Ca(NO_3)_2 and pure gypsum fired at 1290 ℃, was the perfect composition to produce a well formed calcium sulfoaluminate phase in comparison with traditional materials.