Preparation and accelerated carbonation of low temperature sintered clinker with low Ca/Si ratio
A novel clinker with low Ca/Si ratio and low sintering temperature was synthesized, and the property of the clinker was tested. A clinker sintered from industrial raw materials mainly contains rankinite (Ca3Si2O7), pseudowollastonite (Ca-3(Si3O9)) and ferrosilite ((Ca,Mg,Fe,Al)(2)Si2O6). Quantitative analysis of the mineral composition was performed via X-ray powder diffraction using the Rietveld method. Results showed that the optimal formation region of the clinker was at 1300 degrees C for 4 h, resulting in a Ca/Si ratio of 1.27 and 72.7% rankinite, 24.6% pseudowollastonite and 2.7% ferrosilite. The hardening of the clinker occurred mainly due to the carbonation of rankinite and pseudowollastonite yielding CaCO3 and SiO2. Carbonation depth was determined using confocal laser scanning microscopy (CLSM). Experiments indicated that the carbonation depths of the clinker in accelerated carbonation conditions were 659 +/- 20 mu m, 787 +/- 18 mu m and 1118 +/- 98 mu m for 1, 3, and 28 days of carbonation, respectively. Moreover, well-developed calcite crystals could form a network-like and interconnected structure, further enhancing its performance. (C) 2016 Elsevier Ltd. All rights reserved.