由硅酸钙渣组成的胶凝材料的水化特性及环保性能。

Hydration characteristics and environmental friendly performance of a cementitious material composed of calcium silicate slag.

机构信息

School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China; Beijing Key Laboratory of Rare and Precious Metals Green Recycling and Extraction, University of Science and Technology Beijing, Beijing 100083, China.

School of Metallurgical and Ecological Engineering, University of Science and Technology Beijing, Beijing 100083, China.

出版信息

J Hazard Mater. 2016 Apr 5;306:67-76. doi: 10.1016/j.jhazmat.2015.11.055. Epub 2015 Dec 2.

DOI:10.1016/j.jhazmat.2015.11.055

PMID:26691955

Abstract

Calcium silicate slag is an alkali leaching waste generated during the process of extracting Al2O3 from high-alumina fly ash. In this research, a cementitious material composed of calcium silicate slag was developed, and its mechanical and physical properties, hydration characteristics and environmental friendly performance were investigated. The results show that an optimal design for the cementitious material composed of calcium silicate slag was determined by the specimen CFSC7 containing 30% calcium silicate slag, 5% high-alumina fly ash, 24% blast furnace slag, 35% clinker and 6% FGD gypsum. This blended system yields excellent physical and mechanical properties, confirming the usefulness of CFSC7. The hydration products of CFSC7 are mostly amorphous C-A-S-H gel, rod-like ettringite and hexagonal-sheet Ca(OH)2 with small amount of zeolite-like minerals such as CaAl2Si2O8·4H2O and Na2Al2Si2O8·H2O. As the predominant hydration products, rod-like ettringite and amorphous C-A-S-H gel play a positive role in promoting densification of the paste structure, resulting in strength development of CFSC7 in the early hydration process. The leaching toxicity and radioactivity tests results indicate that the developed cementitious material composed of calcium silicate slag is environmentally acceptable. This study points out a promising direction for the proper utilization of calcium silicate slag in large quantities.

摘要

硅酸钙渣是从高铝粉煤灰中提取 Al2O3 过程中产生的一种堿浸出废渣。本研究开发了一种以硅酸钙渣为胶凝材料的胶凝材料，研究了其力学性能、物理性能、水化特性和环保性能。结果表明，通过含有 30%硅酸钙渣、5%高铝粉煤灰、24%矿渣、35%熟料和 6%FGD 石膏的试件 CFSC7 确定了硅酸钙渣胶凝材料的最佳设计。该混合系统具有优异的物理和机械性能，证实了 CFSC7 的实用性。CFSC7 的水化产物主要为无定形 C-A-S-H 凝胶、棒状钙矾石和六方片状 Ca(OH)2，以及少量沸石状矿物，如 CaAl2Si2O8·4H2O 和 Na2Al2Si2O8·H2O。作为主要的水化产物，棒状钙矾石和无定形 C-A-S-H 凝胶在促进浆体结构密实化方面发挥了积极作用，从而在早期水化过程中促进了 CFSC7 的强度发展。浸出毒性和放射性测试结果表明，开发的硅酸钙渣胶凝材料在环境上是可接受的。本研究为大量合理利用硅酸钙渣指出了一个有前景的方向。