低温环境下液体速凝剂的适应性及强度增强机理研究

硅酸盐通报 ›› 2024, Vol. 43 ›› Issue (1): 61-70.

低温环境下液体速凝剂的适应性及强度增强机理研究

杜爽, 王伟, 乔敏, 曾鲁平, 赵爽, 陈俊松, 吴庆勇, 朱伯淞

江苏苏博特新材料股份有限公司,高性能土木工程材料国家重点实验室,南京 211103

收稿日期:2023-08-02 修订日期:2023-10-16 出版日期:2024-01-15 发布日期:2024-01-16
通信作者: 王伟,博士,工程师。E-mail:wangw@cnjsjk.cn
作者简介:杜爽(1996—),男,助理工程师。主要从事速凝剂与喷射混凝土的研究。E-mail:dushuang@cnjsjk.cn
基金资助:
国家重点研发计划(2021YFB2601000);江苏省自然科学基金(BK20221199,BK20211030,BK20211031)

Adaptation and Strength Enhancement Mechanisms of Liquid Accelerators in Low Temperature

DU Shuang, WANG Wei, QIAO Min, ZENG Luping, ZHAO Shuang, CHEN Junsong, WU Qingyong, ZHU Bosong

State Key Laboratory of High Performance Civil Engineering Materials, Jiangsu Sobute New Materials Co., Ltd., Nanjing 211103, China

Received:2023-08-02 Revised:2023-10-16 Online:2024-01-15 Published:2024-01-16

摘要/Abstract

摘要： 速凝剂广泛应用于喷射混凝土中,可实现混凝土的快速凝结硬化。本文研究了碱性和无碱液体速凝剂在20和5 ℃环境下的促凝机理和强度增强规律,并结合水化热、XRD、TG和SEM等测试手段,分析了不同类型速凝剂对水泥水化进程和促凝机理的影响。结果表明:当无碱速凝剂掺量为8%(质量分数,下同)和有碱速凝剂掺量为5%时即可满足《喷射混凝土用速凝剂》(GB/T 35159—2017)中初凝时间不大于5 min,终凝时间不大于12 min的要求;低温(5 ℃)环境会延缓净浆终凝时间,降低掺速凝剂砂浆的早期强度;无碱速凝剂在20和5 ℃环境下的28 d强度仍在增加,而有碱速凝剂出现强度倒缩现象。高浓硫酸铝、常规硫酸铝、含氢氟酸类速凝剂均是通过水化生成钙矾石(AFt)和水化硅酸钙(C-S-H)凝胶等水化产物来提供早期强度和缩短凝结时间,而偏铝酸钠类速凝剂则是通过消耗石膏和生成水化铝酸钙(C-A-H)凝胶和氢氧化钙(CH)等水化产物来提供早期强度和缩短凝结时间;低温环境会使高浓硫酸铝、常规硫酸铝、含氢氟酸类速凝剂作用的水泥中AFt和C-S-H等水化产物含量减少,使强度下降。而掺偏铝酸钠类速凝剂的水泥水化产物受低温环境的影响,导致CH的生成量减少,减弱了CH对后期强度的不利影响。

关键词: 速凝剂, 温度, 水化, 抗压强度, 微观形貌, 促凝机理

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.

Key words: accelerator, temperature, hydration, compressive strength, microstructure, setting-promoting mechanism

中图分类号:

TU528

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.

DU Shuang, WANG Wei, QIAO Min, ZENG Luping, ZHAO Shuang, CHEN Junsong, WU Qingyong, ZHU Bosong. Adaptation and Strength Enhancement Mechanisms of Liquid Accelerators in Low Temperature[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2024, 43(1): 61-70.

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