流化床气相沉积法改性粉煤灰及其水化特征  

Modification of Fly Ash Using Fluidized Bed Reactor-Vapor Deposition and Its Effect on Hydration of Cement Paste and Mortar

作　　者：李晨[1] 朱洪波[1] 吴梦雪[1] 蒋正武[1] 

机构地区：[1]同济大学先进土木工程材料教育部重点实验室,上海201804

出　　处：《建筑材料学报》2016年第6期1004-1012,共9页Journal of Building Materials

基　　金："十二五"国家科技支撑计划项目(2014BAL03B02);国家自然科学基金资助项目(51678442;51478348);国家高铁联合基金资助项目(U1534207);上海市科委重点项目(14DZ1202302;15DZ1205003)

摘　　要：采用流化床气相沉积法,将NaOH,Na_2SO_4等改性材料进行雾化,沉积于粉煤灰颗粒表面.采用扫描电子显微镜(SEM)及傅里叶变换红外光谱仪(FTIR)分析了改性材料结晶特征及其对粉煤灰的溶蚀机理,测试并分析了改性粉煤灰-水泥净浆、改性粉煤灰-水泥砂浆的强度发展,同时通过SEM,X射线衍射(XRD)研究了改性粉煤灰-水泥净浆水化进程.结果表明:NaOH可以与粉煤灰发生溶蚀反应,使其中的Si—O键断裂,粉煤灰的水化活性得以提高;Na2SO_4在粉煤灰表面晶粒尺寸更小、分布更均匀,并能在水化过程中存留于粉煤灰表面,促进了粉煤灰及其附近水泥熟料的水化;采用流化床气相沉积法,上述两种改性材料均可提高粉煤灰颗粒与水泥基体的锚固力,促进水泥石强度发展;当NaOH和Na2SO_4掺量(质量分数)分别为0.23%,1.17%时,水泥净浆和砂浆强度显著提高,并高于同等掺量下用传统化学激发法制备的水泥净浆和砂浆强度.Fluidized bed reactor-vapor deposition（FBR-VD） was utilized to modify fly ash, in which NaOH or Na2 SO4 was deposited onto the surface of the fly ash beads. The crystallization and leaching processes were investigated by scanning electron microscopy （SEM） and Fourier transform infrared spectrometer （FTIR）. The strength developments of cement paste and mortar with modified fly ash were analyzed. The hydration process of cement paste was investigated based on SEM and X-ray diffractometer（XRD）. Results figure out that leaching happens between fly ash and NaOH, breaking the Si-O bond and improving the hydration activity of fly ash. The crystals of Na2 SO4 are smaller in size and better distributed and it remains undissolved in the cement paste, which enhances the hydration of the fly ash as well as the cement clinker nearby. These two effects may strengthen the anchor between the cement matrix and the fly ash and benefit the strength development. When the contents （by mass） of NaOH and Na2SO4 are 0.23% and 1.17% respectively, higher strengths of the cement paste and cement mortar are achieved, as compared to those with traditional chemical activation.

关 键 词：粉煤灰 表面改性 流化床气相沉积法 水化进程 

分 类 号：TQ172.9[化学工程—水泥工业]