碱激发高钙粉煤灰发泡地聚合物的制备及机理

Preparation and Mechanism of Foaming Geopolymer with Alkali Activated High Calcium Fly Ash

为促进高钙粉煤灰高附加值利用,以粉煤灰为主要原料,采用水玻璃碱激发方式,获得具有优异力学性能的地聚合物,进而以过氧化氢为发泡剂,十二烷基磺酸钠(SDS)为稳泡剂,优化发泡工艺,制备多孔发泡地聚合物,并采用Image-Pro Plus图像软件对发泡截面孔径分布进行分析,利用XRD、FTIR和SEM-EDS对发泡地聚合物微观结构进行表征。结果表明:在液固比为0.50、碱当量为10%(质量分数)、水玻璃模数为1.50、H_(2)O_(2)掺量为3%(质量分数)、SDS掺量为0.3%(质量分数)和80℃发泡4 h条件下,标准养护制备的试块28 d抗压强度为1.78 MPa,表观密度为631 kg/m^(3)。发泡地聚合物孔径小且分布均匀,密度较低。聚合产物为少量C-S-H凝胶和大量钙铝钠协同反应产生的N(C)-A-S-H凝胶,保证了发泡地聚合物的机械强度。

In order to promote the high value-added utilization of high calcium fly ash,the geopolymer with excellent mechanical properties was prepared using fly ash as main raw material by water glass alkali excitation.Then,hydrogen peroxide was introduced as foaming agent,sodium dodecyl sulfate(SDS)was used as foaming stabilizer and the foaming process was optimized to prepare porous foaming geopolymer.The pore size distribution of foaming section was analyzed by Image-Pro Plus image software and the microstructure of foaming geopolymer was characterized by XRD,FTIR and SEM-EDS.The results show that under the conditions of liquid-solid ratio of 0.50,alkali equivalent of 10%(mass fraction),water glass modulus of 1.50,H_(2)O_(2)content of 3%(mass fraction),SDS content of 0.3%(mass fraction)and foaming at 80℃for 4 h,the 28 d compressive strength of specimen after standard curing is 1.78 MPa,and the apparent density is 631 kg/m^(3).Foaming geopolymer has small pore size and uniform distribution,resulting in low density.The polymerization product is a small amount of C-S-H gel and a large amount of N(C)-A-S-H gel produced by the synergistic reaction of calcium,aluminum and sodium,which ensures the mechanical strength of foaming geopolymer.