早期地聚合反应过程的~1H低场核磁共振

Geopolymerization Process at Early Age by ~1H Low Field Nuclear Magnetic Resonance

在地聚合物体系中,浆体的组成及微观结构对于其硬化后的性能有着重要的影响。利用1H低场核磁共振仪对比研究了纯偏高岭土基(MK-100)及掺高钙粉煤灰(MK-85)的地聚合物的早期反应过程,探测了不同结合状态的水分子的质子信号,获得了水的纵向弛豫时间(T1)和横向弛豫时间(T2)。研究表明:1H低场核磁共振法适宜于研究地聚合物的早期反应过程,根据浆体纵向弛豫时间T1的加权平均值,可以将早期地聚合反应过程划分为加速期、减速期和稳定期3个阶段;高钙粉煤灰的加入使地聚合物浆体加速期缩短,减速期延长。早期地聚合反应过程中水的横向弛豫时间T2可以很好地表征毛细水或凝胶水的变化趋势。高钙粉煤灰的加入会延缓毛细水向凝胶水的转变过程。

In a geopolymeric system, the composition and microstructure of the geopolymer paste have effects on the performance of the hardened system. The pure metakaolin based (MK-100) and metakaolin-fly ash based (MK-85) geopolymers were characterized by 1H low field nuclear magnetic resonance (1H-NMR). In order to explore the geopolymeriztion process at early age, the proton signal of different combinations of water state was examined, and the spin-lattice relaxation time (T1) and longitudinal relaxation time (T2) were obtained. The results show that it is suitable to analyze the geopolymeriztion process at early age by the 1H NMR. According to the evolution curve of the weighted average value of T1, the geopolymerization process at early age could be confirmed and divided into three successive stages, i.e., acceleration period, deceleration period and stabilization period. The incorporation of fly ash in the metakaolin based geopolymer system would shorten the acceleration period and extend the deceleration period. The weighted average value of T2 could cause capillary water and gel water. The transformation from capillary water to gel water in the presence of fly ash could be retarded.