Characterization of Pozzolanic Reaction and Its Effect on the C-S-H Gel in Fly Ash-cement Paste  

作　　者：王磊 何真 

机构地区：[1]State Key Laboratory of Water Resources and Hydropower Engineering Science,Wuhan University

出　　处：《Journal of Wuhan University of Technology(Materials Science)》2011年第2期320-325,共6页武汉理工大学学报（材料科学英文版）

基　　金：Funded by the National Basic Research Program of China (973 Program)(No. 2009CB623201);the National Natural Science Foundation of China (No. 50972109);the Doctoral Program of Higher Education (No. 20090141110021)

摘　　要：High resolution solid-state 29Si MAS NMR,combined with XRD,SEM and FTIR were used to characterize the pozzolanic activity of FA,type of main pozzolanic reaction products,and the effect of pozzolanic reaction on the C-S-H microstructure in fly ash-cement （FC） paste.The experimental results indicate that in the hydrated FC paste with 30% dosage of FA at 3 d,FA partially participated in the pozzolanic reaction,while,at 120 d,FA largely reacts.During the hydration of FC paste at laboratory temperature,the pozzolanic reaction products are C-S-H gel rather than zeolitic gel.Moreover,after the covalent bonds of Si-O-Si,Si-O-Al and Al-O-Al in the structure of FA are broken,monosilicates Si-OH and Al-OH groups form,these chemical species can connect C-S-H dimers,thus producing more Al-free C-S-H and aluminous C-S-H than in the plain cement paste.The increased content of Al for Si substitution in the bridging tetrahedra of C-S-H may decrease the stability of C-S-H,which results in a rather obvious loss in the mechanical strength of hardened FC paste.High resolution solid-state 29Si MAS NMR,combined with XRD,SEM and FTIR were used to characterize the pozzolanic activity of FA,type of main pozzolanic reaction products,and the effect of pozzolanic reaction on the C-S-H microstructure in fly ash-cement （FC） paste.The experimental results indicate that in the hydrated FC paste with 30% dosage of FA at 3 d,FA partially participated in the pozzolanic reaction,while,at 120 d,FA largely reacts.During the hydration of FC paste at laboratory temperature,the pozzolanic reaction products are C-S-H gel rather than zeolitic gel.Moreover,after the covalent bonds of Si-O-Si,Si-O-Al and Al-O-Al in the structure of FA are broken,monosilicates Si-OH and Al-OH groups form,these chemical species can connect C-S-H dimers,thus producing more Al-free C-S-H and aluminous C-S-H than in the plain cement paste.The increased content of Al for Si substitution in the bridging tetrahedra of C-S-H may decrease the stability of C-S-H,which results in a rather obvious loss in the mechanical strength of hardened FC paste.

关 键 词：NMR C-S-H microstructure DIMER POLYMERIZATION 

分 类 号：X773[环境科学与工程—环境工程]