硅酸盐通报2024，Vol.43Issue(1)：61-70,10.
低温环境下液体速凝剂的适应性及强度增强机理研究
Adaptation and Strength Enhancement Mechanisms of Liquid Accelerators in Low Temperature
摘要
Abstract
Accelerators are generally applied in shotcrete to achieve rapid setting and hardening of the concrete.Alkaline and alkali-free liquid accelerators were investigated for their setting-promoting mechanism and strength enhancement at 20 and 5 ℃,and the effect of different types of accelerators on the hydration process and setting-promoting mechanism of cement were analyzed by using heat of hydration analysis,XRD,TG and SEM.The results show that when alkali-free liquid accelerators content of 8％(mass fraction,the same below),alkaline liquid accelerators content of 5％the requirements of the initial setting time not more than 5 min,the final setting time not more than 12 min were met.The environment 5 ℃ will delay final setting time of the slurry and reduce early strength of the mortar mixed with accelerator.Alkali-free accelerator still increases in strength at 28 d in 20 and 5 ℃ environments,while alkaline accelerator shows strength collapse.Highly-concentration aluminum sulfate,conventional aluminum sulfate and hydrofluoric acid are hydrated to generate ettringite(AFt)and calcium silicate hydrate(C-S-H)gel to provide early strength and shorten the setting time,while sodium aluminate accelerator is through the consumption of gypsum and the generation of C-S-H and calcium hydroxide(CH)to provide early strength and shorten the setting time.The low-temperature environment will reduce hydration products content such as AFt and C-S-H in cement acted by high-concentration aluminum sulfate,conventional aluminum sulfate,and hydrofluoric acid-based accelerator,resulting in a decrease in strength.The hydration product of cement mixed with sodium meta-aluminate type accelerator is reduced by the generation of CH under the influence of low-temperature environment,which is able to attenuate the adverse effect of CH on the late strength.关键词
速凝剂/温度/水化/抗压强度/微观形貌/促凝机理Key words
accelerator/temperature/hydration/compressive strength/microstructure/setting-promoting mechanism分类
建筑与水利引用本文复制引用
杜爽,王伟,乔敏,曾鲁平,赵爽,陈俊松,吴庆勇,朱伯淞..低温环境下液体速凝剂的适应性及强度增强机理研究[J].硅酸盐通报,2024,43(1):61-70,10.基金项目
国家重点研发计划(2021YFB2601000) （2021YFB2601000）
江苏省自然科学基金(BK20221199,BK20211030,BK20211031) （BK20221199,BK20211030,BK20211031）
