ESEM追踪K-PSDS型地聚合物水泥的水化

In Situ Quantitatively Tracking the Hydration Process of K-PSDS Geopolymer with ESEM

应用环境扫描电镜原位定量追踪K PSDS型地聚合物水泥在相对湿度80%条件下水化产物生成—发展—演化的全过程.结果表明:在水化早期,偏高岭土颗粒松散地堆积在一起,存在许多大空隙;随着龄期的增长,生成的大量海绵状胶体积淀在颗粒表层,并向外扩充;到了后期,颗粒被胶体厚厚包裹,空隙被填满,基体变得非常致密.通过能量散射分析(EDXA)发现,随着水化的进行,K2O与Al2O3,SiO2与Al2O3的摩尔比逐渐减小,最终产物的这两个比值分别为1.28,6.54,接近理论值.另外,在任何龄期均未出现外形规则的结晶产物,而仅生成了一种均匀的海绵状胶体.

A technique of environment scanning electron microscope(ESEM) was used to in situ quantitatively observe and record the hydration process of K-PSDS geopolymer matrix under RH 80%. The ESEM micrographs and corresponding EDXA show that metakaolinite grains pile up loosely at 10 min after mixing, which lead to many large voids. As hydration proceeds, a lot of gel is seen and is gradually precipitated on these grain surfaces. At late stage, these grains are packed by thick gel layers, and voids are fully filled. In situ studies on K-PSDS matrix by EDXA display that the values of n(K_2O)/n(Al_2O_3) and n(SiO_2)/n(Al_2O_3) are continuously reduced with the development of hydration, the values of n(K_2O)/n(Al_2O_3) and n(SiO_2)/n(Al_2O_3) of hydration products at 9 h after mixing are 1.28 and 6.54 respectively, which are near to the theoretical values (1.0, 6.0). In addition, well-developed crystals are not found at any ages, while sponge-like gel is always been observed.