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流化床气相沉积法改性粉煤灰的性能及改性机理
Performance and Modification Mechanism of Fly Ash Modifiedby Fluidized Bed Reactor Vapor Deposition
投稿时间:2018-11-21  修订日期:2019-01-30
DOI:103969/j.issn1007 9629202002018
中文关键词:  粉煤灰  流化床气相沉积  表面改性  火山灰反应
英文关键词:fly ash  fluidized bed reactor vapor deposition(FBR VD)  surface modified  pozzolanic reaction
基金项目:“十三五”国家重点研发计划(2016YFC0701003 03)
     
作者单位
朱洪波
ZHU Hongbo
同济大学先进土木工程材料教育部重点实验室,上海201804
Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Tongji University, Shanghai 201804, China
苟鸿翔
GOU Hongxiang
同济大学先进土木工程材料教育部重点实验室,上海201804
Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education, Tongji University, Shanghai 201804, China
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中文摘要:
      根据粉煤灰(FA)的工业存储条件,开发了流化床试验装置,并且以HCl(HC)、H2SO4(HS)、NaOH(NH)、Na2SO4(NS)和NaCl(NC)为改性材料,通过流化床气相沉积方法(FBRVD)来改性FA.结果表明:HC明显提高了FA水泥浆体的流动性,其他改性材料对FA水泥浆体流动性基本无影响;除了NS略微降低FA水泥浆体各龄期的强度外,其他改性材料均在不同龄期起到增强作用;采用含Cl-改性剂的FA水泥浆体中绝大部分Cl-被固化,可溶性Cl-含量远未达到国家标准规定的限值,不会影响钢筋的安全性;FBRVD方法可将改性材料均匀地沉积于FA表面,沉积微粒尺度在500nm以下;HC和NH改性的FA表面及周围分布的氢氧化钙(CH)呈细长条状,均匀地将FA与水泥石牢固地连接为一体,起到增强作用;NC改性FA颗粒表面呈现密集堆积的CH,对FA水泥浆体7d前的增强效果最为显著;NS改性FA表面虽然堆积了厚层CH,但与水泥石的结合松散,反而造成FA水泥浆体强度略有下降;HS改性FA表面吸附的CH量较少,对FA水泥浆体强度的贡献不大.
英文摘要:
      A fluidized bed experimental device was developed according to the industrial storage condition of the fly ash(FA), and HCl(HC),H2SO4(HS), NaOH(NH), Na2SO4(NS) and NaCl(NC) which were used as the modified materials to modify FA.The results show that all the modified materials have less effect on liquidity of FA by the fluidized bed reactor vapor deposition method(FBR VD), except that HC obviously improved the liquidity. In addition, NS slightly reduces the strength of FA cement paste at different ages, other modified materials all play an enhanced role at different ages, and NC has the most significant enhancement effect before 7d with the activity index over 110%. Although the concentration of Cl- in the hardened paste dissolved in water is significantly increased by using the modifier containing Cl-, the majority of Cl- is cured by FA cement paste. The soluble Cl- content in the cement paste modified with FA does not reach the limit specified by the national standard and does not affect the safety of steel reinforcement. The modified material can be uniformly deposited on the FA surface by FBR VD method, and the scale of sedimentary particles is below 500 nm. A large amount of calcium hydroxide crystal(CH), the cement hydration product, is added to the surface of the modified FA particles in cement, and the FA spheres are overlapped with the cement stones around them. Different modified materials have different effects on the hydration reaction of FA surface, so they show different strength. The CH distributed on the FA surface with HC and NH form a slender strip, which uniformly connect FA firmly with cement stone to enhance the effect. The surface of FA particles modified by NC show dense accumulation of CH, which has the most significant enhancement effect before 7d. Although the thick CH is deposited on the surface of FA modified by NS, it is loosely bound to cement stone, resulting in a slight decrease in strength. The amount of CH adsorbed on the surface of FA modified by HS is less, and its contribution to strength is less.
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