摘要
本研究以硫酸铝和高活性氢氧化铝为原料,制备出一种无氯无碱液体速凝剂。分析了速凝剂对水泥凝结时间、砂浆力学性能的影响及速凝剂的促凝机理。针对所制备速凝剂早期稳定性较差的问题,采用乙二胺四乙酸(EDTA)对其进行改性,成功提高了稳定性,稳定存放期大于30 d。采用X射线衍射(XRD)分析、pH值检测等手段研究其稳定机理,结果表明:速凝剂掺量为5%时,水泥净浆的初凝时间为200 s,终凝时间为380 s,1 d强度大于7 MPa,3 d强度达18.56 MPa,28 d强度保留率为89.3%。速凝剂的主要促凝机理是通过早期形成大量钙矾石,使水泥快速达到初凝的同时大量Ca(OH)_(2)析晶也显著缩短了诱导期;EDTA的加入一方面可降低速凝剂的pH值,抑制NaSiF_(6)的水解析晶;另一方面可与Al^(3+)、Ca^(2+)形成稳定的五元环螯合物,抑制Al^(3+)的水解聚沉失稳与CaSO_(4)、AlF_(3)的析晶沉淀,提高速凝剂的稳定性。
Aluminum sulfate and homemade high-activity aluminum hydroxide were used as raw materials to prepare a chlorine-free and alkali-free liquid accelerator.Effects of the accelerator on the setting time of cement,mechanical properties of mortar,and stable mechanism were analyzed.In view of the poor stability of the accelerator in the early stage,ethylenediamine tetraacetic acid(EDTA),which successfully improved the stability,was used to modify the accelerator.The stable storage period is more than 30 days.The stability mechanism was studied by XRD analysis and pH value detection.Results show that the initial setting time,the final setting time,the compressive strength of 1 d,the compressive strength of 3 d,and the 28 d strength retention rate are 200 s,380 s,greater than 7 MPa,18.56 MPa,and 89.3%,respectively,when the content of accelerator is 5%.The setting mechanism of the accelerator is to form a large amount of ettringite at early age,so that the cement can quickly reaches the initial setting.Large amount of Ca(OH)_(2)crystallization significantly shortens the induction period and make the cement quickly approach the final setting.EDTA reduces the pH value of the accelerator and inhibits the hydrolytic crystals of NaSiF_(6).On the other hand,EDTA binds with Al^(3+) and Ca^(2+) to form a stable five-membered ring chelate,as well as suppresses the hydrolysis of Al^(3+),and the crystallization or precipitation of CaSO_(4)and AlF_(3),which all improves the stability of accelerator.
作者
张国丽
武志红
邓悦
刘佳元
王耀
王宇斌
ZHANG Guoli;WU Zhihong;DENG Yue;LIU Jiayuan;WANG Yao;WANG Yubin(College of Materials Science and Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,China;State Key Laboratory of Advance Refractories,Sinosteel Luoyang Institute of Refractories Research Co.,Ltd.,Luoyang 471039,China;School of Resources Engineering,Xi’an University of Architecture and Technology,Xi’an 710055,Shaanxi,China)
出处
《材料科学与工程学报》
CAS
CSCD
北大核心
2022年第3期466-472,536,共8页
Journal of Materials Science and Engineering
基金
国家自然科学基金资助项目(51974218)
西安建筑科技大学基础研究基金资助项目(JC1496)
先进耐火材料国家重点实验室开放基金资助项目(SKLAR201905)。
关键词
无碱液体速凝剂
乙二胺四乙酸
稳定性
机理
Alkali-free liquid accelerator
Ethylene diamine tetraacetic acid
Stability
Mechanism
