Study on Properties of Alkali-Activated and Thermal Modification Coal Gangue-Based Grouting Material
In order to increase the use of coal gangue in grouting materials,the activity and performance of activated coal gangue-based grouting materials were studied.The influences of activation temperature,coal gangue proportion,and chemical activators on the fluidity,setting time and compressive strength of thermally modified coal gangue-based grouting materials were analyzed.The phases of coal gangue materials before and after thermal activation were analyzed using X-ray fluorescence spectroscopy(XRF)and X-ray diffraction analysis(XRD),and the leaching characteristics of silicon and aluminum of activated coal gangue were analyzed using inductively coupled plasma optical emission spectroscopy(ICP-OES).The activated material was further activated by adding two chemical activators,NaOH and Na2SiO3.The results show that the cementitious material with an activation temperature of 800 ℃,a coal gangue proportion of 66.7％,and a Na2SiO3 dosage of 4％has the best activation effect,which has a flow distance of 19.3 cm and a compressive strength of 13.47 MPa at 28 d.Thermogravimetric analysis of the hydration process shows that under this activation condition,the mass loss was the highest between 650-800℃,and the amount of calcite generated reached 8.81％.Adding dolomite will delay the agglomeration effect of coal gangue during thermal activation,making its optimal activation temperature reach 800 ℃.Moderate addition of chemical activators can accelerate the hydration process,while the opposite will delay the hydration process.
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