粉煤灰基地聚物水泥胶凝材料的早期工作性能

Early Workability Performance of Fly Ash-based Geopolymer Cement Binder

采用水泥净浆流动度和流变测试两种方法研究了粉煤灰-硅灰-偏高岭土地聚物体系的早期性能,运用水化放热、X射线衍射仪(XRD)、热重分析(TG)和红外光谱(FTIR)等手段深入分析了掺入硅灰和偏高岭土后粉煤灰地聚物水化反应和产物的变化情况。研究结果表明,当静置时间相同时,纯粉煤灰组地聚物浆体的流动度最大。硅灰和偏高岭土的掺入使得胶凝体系屈服应力和塑性黏度有所增加。所有浆体的剪切应力-剪切速率均表现为Bingham线性模型的增长趋势。复掺10%粉煤灰和10%偏高岭土组屈服应力和塑性黏度在四组配合比中最高,分别为1.73 Pa·s^(-1)和65.8 Pa。纯粉煤灰在激发剂作用下的水化放热速率曲线在经历了初始的溶解放热后趋于平缓,而硅灰和偏高岭土的加入则使体系在水化10~20 h的峰强有所提高。XRD等微观分析结果表明,粉煤灰-硅灰-偏高岭土地聚物的早期水化产物包括莫来石、石英,方沸石和碳酸钙,其中以莫来石和石英为主。

The early workability performance of fly ash-silica fume-metakaolin polymer system was studied by two methods,i.e.,cement paste fluidity and rheological test.The hydration reaction and product changes of fly ash geopolymer incorporating silica fume and metakaolin were analyzed by means of hydration exothermic,X-ray diffraction(XRD),thermogravimetric analysis(TG)and Fourier-transform infrared spectroscopy(FTIR).The results show that when the resting time was the same,the fluidity of pure fly ash geopolymer was the largest.The addition of silica fume and metakaolin increased the yield stress and plastic viscosity of the geopolymer system.The relation of shear stress shear and rate of all pastes showed the growth trend of Bingham linear model.The yield stress and plastic viscosity of the group mixed with 10% fly ash and 10% metakaolin were the highest among the four groups,which are 1.73 Pa·s^(-1) and 65.8 Pa,respectively.The hydration exothermic rate curve of pure fly ash under the action of activator tended to be flat after the initial dissolution exothermic,while the addition of silica fume and metakaolin increased the peak of the system at 10-20 h of hydration.XRD and other microscopic analysis results showed that the early hydration products of fly ash-silica fume-metakaolin geopolymer included mullite,quartz,analcite and calcium carbonate,mainly showing mullite and quartz.