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加速碳化对水化硅酸钙显微结构的影响
作者:常钧 房延凤 尚小朋 王静茹 
单位:大连理工大学土木工程学院 辽宁大连 116024 
关键词:水化硅酸钙 加速碳化 显微结构 核磁共振 
分类号:TU528
出版年,卷(期):页码:2015,43(8):0-0
DOI:10.14062/j.issn.0454-5648.2015.08.01
摘要:

废弃水泥石等固体废弃物碳酸化不仅能够永久固碳,还可实现固体废弃物的再利用,减少对环境的污染。水化硅酸钙(C-S-H)是最主要的可碳化成分之一。本研究合成了钙硅(C/S) 比为1.50 C-S-H,研究了加速碳化对其显微结构的影响。用Rietveld 全谱拟合的方法和热重-质谱联用的方法对碳化产物进行定量分析,用扫描电镜,N2 吸附和29Si 固体核磁共振对碳化前后的显微结构进行表征。结果表明:在99.9% CO20.2 MPa 压力下加速碳化2 h 之后,生成了3 种不同晶型的碳酸钙和的硅胶,碳酸钙从300℃开始分解,文石和球霰石具有较低的分解温度,结晶良好的方解石分解温度较高;多孔结构硅胶具有更高的吸附能力,但C-S-H 碳化后的平均孔径从10.33 nm 减小到6.69 nm,比表面积85.6 m2/g 减小到67.7 m2/g,这是由于大量的结构致密的碳酸钙晶体堆积造成的;C-S-H 双层硅氧链之间的CaO 层逐渐脱去与CO2 反应,硅氧四面体被质子化或与邻近的硅氧四面体链接,形成了聚合度更高的Q3 Q4 结构。

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Mineral carbonation of alkaline solid waste such as waste cement paste is a promising way for carbon capture and storage.The solid waste can be reused, leading to the reduction of environmental pollution. Calcium silicate hydrate(C-S-H) is one of thedominant mineral phases that can be carbonated. In this paper, C-S-H with C/S ratio of 1.50 was synthesized, and the microstructurechanges induced by accelerated carbonation were investigated. The carbonation products were characterized by the Rietveldrefineness (QXRD), and the microstructure was analyzed by scanning electron microscopy, nitrogen physisorption and nuclearmagnetic resonance, respectively. The results indicate that the carbonation leads to the formation of calcium carbonate with threedifferent polymorphs and silica gel, calcium carbonate begins to decompose at 300 , aragonite and vaterite show a relatively lowdecomposition temperature, and well-crystallized calcite decomposes at a higher temperature. In porous silica gel, the average porediameter decreases from 10.33 nm to 6.69 nm, and the specific surface area decreases from 85.6 m2/g to 67.7 m2/g due to the stackof dense calcium carbonate. The Ca-O decalcifies from inter layer of C-S-H and the residual silica tetrahedron protonates or links withother silica tetrahedron to form Q3 or Q4 with more polymerization degree.

基金项目:
国家自然科学基金(51172096);教育部“新世纪优秀人才支 持计划”和中央高校基本科研业务费专项资金资助。
作者简介:
通信作者:常 钧(1970—),男,博士,教授。
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