钙质掺合料对碱激发低品位粉煤灰混凝土性能的影响

以碱激发低品位粉煤灰混凝土为研究对象,探究了钙质掺合料(石灰、硅酸盐水泥)种类与掺量对粉煤灰混凝土凝结特性、工作性能及力学性能的影响,并结合SEM/EDS、压汞法等微观测试方法,分析了石灰的引入对碱激发低品位粉煤灰混凝土的作用机理。结果表明,在一定掺量范围内(≤10%),两种掺合料都能显著加快碱激发低品位粉煤灰混凝土的凝结硬化,而对其工作性能无明显不良影响。石灰对低品位粉煤灰的激发效果要优于硅酸盐水泥,且能够较好地提高混凝土的早期强度。微观分析表明石灰与激发剂共同作用,加速粉煤灰地质聚合反应,促使N-A-S-H和C-A-S-H、C-S-H等凝胶生成,从而提高混凝土强度。

Effects of admixtures on alkali-activated low rank fly ash concrete

It aims to investigate the influence of calcareous admixture (including lime and Portland cement) on the properties of alkali activated low rank fly ash.The setting time,workability and mechanical properties of the binder and concrete were measured.The role of lime in the concrete was discussed by using SEM/EDS and MIP.The results show at the content of no more than 10%,the admixtures can greatly accelerate the setting and hardening of the alkali-activated fly ash,and have no obvious adverse effect on the workability of the concrete.The activation of lime on low rank fly ash is better than that of Portland cement,and lime can obviously improve the early strength of fly ash concrete.According to microstructure analysis,the geopolymerization of fly ash will be accelerated by the interaction of lime and alkali solutions due to the formation of N-A-S-H,C-A-S-H and C-S-H gels.Therefore,the strength of fly ash concrete is improved.