微波场下微珠对碱激发粉煤灰早期力学性能的影响

基于多级微波养护制度,在经浮选、磁选后的焙烧粉煤灰中掺入炭粒、漂珠和磁珠等微珠,研究微珠在微波场下的水化行为及其对碱激发粉煤灰基胶凝材料早期力学性能的影响,并采用X射线衍射(XRD)、傅里叶红外光谱(FTIR)、场发射扫描电子显微镜(FESEM)分析其微观结构.结果表明:掺加5%炭粒对微波养护碱激发粉煤灰基胶凝材料的早期抗压强度没有影响,5%漂珠和磁珠能够显著提升其早期抗压强度;微波养护试样中都生成了羟基方钠石和钠系菱沸石,炭粒、漂珠和磁珠均不会改变水化产物的类型;碱激发反应能够在结构中空的漂珠内外同时进行,因此可以适当缩短富含漂珠的碱激发粉煤灰试样的微波养护时间.

Effect of Fly Ash Micro beads on the Early Age Mechanical Property of Alkali Activated Fly Ash Materials under Microwave Field

Based on the multi stage microwave curing regime, fly ash groups rich in various micro bead(carbon particle, floating bead and magnetic bead) were prepared in incorporation various micro bead into roasted fly ash, which were obtained by flotation, magnetic separation and roasting. The hydration behavior of the above micro beads under microwave field and its effect on the early mechanical properties of alkali activated fly ash based cementitious materials(AAFA) were studied. And microscopic of samples were analyzed by X ray diffraction(XRD), Fourier transform infrared spectrometer(FTIR) and field emission scanning electron microscope(FESEM). The results show that the incorporation of 5% carbon particle has little effect on the early age compressive strength of microwave cured alkali activated fly ash based cementitious materials, while the addition of 5% floating bead and magnetic bead can significantly enhance their early compressive strength. In all samples, hydrosodalite and chabazite Na form during microwave curing process. The addition of carbon particle, floating bead and magnetic bead has not cause the change of hydration products type of samples. The alkali activating reaction take place both inside and outside the hollow floating bead simultaneously, thus floating bead can shorten the microwave curing duration of the samples to reach its peak strength.