Fly Ash-based Geopolymers:Effect of Slag Addition on Efflorescence  

作　　者：姚晓 YANG Tao ZHANG Zhuhua 

机构地区：[1]Faculty of Materials Science and Engineering,Nanjing Tech University,Nanjing 210009,China [2]Faculty of Engineering and Surveying,University of Southern Queensland,Toowoomba 4350,Australia

出　　处：《Journal of Wuhan University of Technology(Materials Science)》2016年第3期689-694,共6页武汉理工大学学报（材料科学英文版）

基　　金：Funded by the Jiangsu Higher Education Institutions for a project PAPD(Priority Academic Program Development),Program for Changjiang Scholars and Innovative Research Team in University(PCSIRT);(No.IRT1146);Graduate Education Innovation Project in Jiangsu Province(No.CXLX13_409);supported by University of Southern Queensland and an ARC-linkage project

摘　　要：Blended fly ash/blast-furnace slag geopolymers are focused on due to their excellent mechanical and chemical resistant properties. We investigated the effect of slag partial substitution for fly ash on the efflorescence of the resulting geopolymers. The efflorescence of geopolymer binders was inspected and evaluated through leaching tests. The efflorescence deposits on surface of the geopolymer binders were analyzed using XRD and SEM-EDS. The results showed that sodium and calcium cations leached from geopolymer binders reacted with the atmospheric CO2 and formed the crystal deposits, gaylussite and calcite, in the forms of granular and angular crystal particles. The slag addition led to a refinement of the pore structure of fly ash-based geopolymers, but an increment in the concentration of alkali leaching. The crystal deposits gradually developed in the pore volume of the binders, and finally exceeded the capacity of pore volume. The extent of efflorescence on the surface of specimens increased with the slag substitution. The visible efflorescence is therefore a result of available alkalis and pore sizes and volumes. Higher concentration of available alkalis and smaller pores （and volume） will lead to more intensive efflorescence.Blended fly ash/blast-furnace slag geopolymers are focused on due to their excellent mechanical and chemical resistant properties. We investigated the effect of slag partial substitution for fly ash on the efflorescence of the resulting geopolymers. The efflorescence of geopolymer binders was inspected and evaluated through leaching tests. The efflorescence deposits on surface of the geopolymer binders were analyzed using XRD and SEM-EDS. The results showed that sodium and calcium cations leached from geopolymer binders reacted with the atmospheric CO2 and formed the crystal deposits, gaylussite and calcite, in the forms of granular and angular crystal particles. The slag addition led to a refinement of the pore structure of fly ash-based geopolymers, but an increment in the concentration of alkali leaching. The crystal deposits gradually developed in the pore volume of the binders, and finally exceeded the capacity of pore volume. The extent of efflorescence on the surface of specimens increased with the slag substitution. The visible efflorescence is therefore a result of available alkalis and pore sizes and volumes. Higher concentration of available alkalis and smaller pores （and volume） will lead to more intensive efflorescence.

关 键 词：GEOPOLYMER EFFLORESCENCE pore structure fly ash SLAG 

分 类 号：TQ317[化学工程—高聚物工业]