用环境扫描电镜原位定量研究K-PS型地聚合物水泥的水化过程

Quantitative in situ study on the hydration process of K-PS geopolymer with ESEM

应用环境扫描电镜原位定量追踪K PS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 .实验结果表明 :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 ;随龄期的增长 ,生成了大量的海绵状胶体 ,积淀在颗粒表层 ,并向外扩充 ;到后期颗粒被胶体厚厚包裹 ,大空隙被逐渐填满 ,基体变得比较致密 .通过能量散射X射线能谱分析(EDXA)发现随着水化的进行 ,n(K) /n(Al)不断增大 ,而n(Si) /n(Al)逐渐减小 ,水化 4h的n(K) /n(Al) =0 99,n(Si) /n(Al) =1 49.另外 ,在任何龄期均未出现形貌规则的结晶产物 。

A technique of environmental scanning electron microscope (ESEM) was used to in situ quantitatively observe and record the hydration process of K-PS geopolymer matrix under relative humidity 80%. The ESEM micrographs and corresponding energy dispersive X-ray analysis (EDXA) show that the metakaolinite grains pack loosely at 10 minutes after being mixed, which leads to many large voids. As hydration proceeds, a lot of gels are formed and gradually precipitate on the metakaolinite grain surfaces. At later stage, these grains are covered by thick gel layers, and voids are mostly filled. EDXA displays that there is an increase in the ratio of n(K)/n(Al), but a decrease in the ratio of n(Si)/n(Al) of products with the development of hydration. The contents of n(K)/n(Al) and n(Si)/n(Al) of hydration products at 4 h after being mixed are 0.99 and 1.49, respectively, which are close to the theory values(n(K)/n(Al)=1.0, n(Si)/n(Al)=1.0), In addition, well-developed crystals are not found at any ages, while the sponge-like gel is always observed.