微波活化煤矸石对水泥基材料的性能影响

Effect of Microwave Activated Coal Gangue on Properties of Cement-based Materials

本研究采用微波对煤矸石粉进行高温辐射以激发其潜在活性,使其作为掺合料高效运用于水泥基材料中。通过红外温度仪测量煤矸石粉微波温度,进一步利用激光粒度分析、XRD和SEM对活性煤矸石粉的矿物组成和微观形貌进行表征,对比分析了未活化和活化后煤矸石胶砂的流动度及力学性能,研究了活性煤矸石粉的水化机理。结果表明:微波高温后,煤矸石粉的粒度整体减小,颗粒圆润化和粒径均匀化。此外,微波高温使得煤矸石结构疏松多孔,所需游离水增加,胶砂流动度下降。当微波温度为500~600℃,煤矸石粉掺量为10%、20%、30%时,试块的28 d抗压强度比未活化组分别提高了46.5%、37.9%、51.1%。活性煤矸石浆体中煤矸石粉表面生成了水化活性较好的C-S-H和C-A-S-H凝胶,发挥了火山灰效应,而未反应的煤矸石粉则填充在浆体空隙中,进而提高了胶砂的力学性能。

In this study,high-temperature microwave radiation was used to stimulate the potential activity of coal gangue powder,so that it could be used as an admixture in cement-based materials.The temperature of coal gangue powder was measured by infrared thermometer.Further,laser particle size analysis,XRD and SEM were used to characterize the mineral composition and microscopic morphology of activated coal gangue powder.The flowability and mechanical properties of unactivated and activated coal gangue mortar were compared and analyzed,and the hydration mechanism of activated coal gangue powder was studied.The results showed that after microwave heating,the particle size of coal gangue powder decreased as a whole,and the particles were rounded and uniform.In addition,the high temperature of the microwave caused the structure of coal gangue loose and porous,the required free water added,and the flowability of mortar reduced.When the microwave tempe-rature was 500—600℃and the content of coal gangue powder was 10%,20%and 30%,the 28 d compressive strength of the specimen was 46.5%,37.9%and 51.1%higher than that of the unactivated group,respectively.The C-S-H and C-A-S-H gels with good hydration activity were formed on the surface of coal gangue powder in the active coal gangue slurry,which played a pozzolanic effect,while the unreacted coal gangue powder was filled in the gap of the slurry,thus improving the mechanical properties of the mortar.