Study on activation of calcium-added coal gangue with composite mineralizers

Coal gangue from Yixing, Jiangsu was investigated. After calcium was introduced into coal gangue, activated samples were prepared under different high temperatures by adding composite mineralizers. X-ray diffraction(XRD) method and infrared absorption spectrometry(IR) method were used to analyze their structure characteristics. Cementitious properties of activated samples were also detected. The research results were listed as follows: Under all activation conditions from 1000°C to 1100°C, CA is produced in activated samples due to the effect of composite mineralizers. CS, Ca3Al10O18 may exist in low activation conditions, such as under 1000°C and holding 0.5 h or 1.0 h. And when it comes to 1050°C with holding 0.5 h, Ca3Al10O18 disappears. CS disappears at 1050°C with holding 1.0 h and at the same time [Ca4(Al2O4)]3- generates. Different activated samples have different cementitious properties. Activated samples calcined at 1050°C, 0.5 h show the greatest influence on cement strength, and its compressive strength of 28d can reach 70.16 MPa, with substituting 30% mass of cement.