TY - JOUR
T1 - Adsorption and Desorption Characteristics of Alkali Ions in Hydrated C3S-nano SiO2 Pastes
AU - Lu, Guosen
AU - Deng, Min
AU - Mo, Liwu
N1 - Publisher Copyright:
© 2018, Wuhan University of Technology and Springer-Verlag GmbH Germany, part of Springer Nature.
PY - 2018/10/1
Y1 - 2018/10/1
N2 - C3S pastes containing 0%, 5%, 10%, and 15% nano-SiO2 mixed with de-ionized water and alkali solutions were prepared. When C3S was completely hydrated, the pastes were ground into powders with a particle size less than 80 μm. Adsorption and desorption characteristics of alkali ions adsorbed by C3S-nano SiO2 pastes mixed with de-ionized water immersed in alkali solutions and those in C3S-nano SiO2 pastes mixed with alkali solutions, were investigated. Meawhile, the adsorption mechanisms of alkali ions were discussed. Results showed that the contents of alkali ions adsorbed by C3S-nano SiO2 pastes mixed with de-ionized water increased with increasing substitution levels of nano-SiO2 and/or the initial alkali concentrations. In C3S-nano SiO2 pastes mixed with de-ionized water, each paste was characterized by having a fixed alkali-adsorption capacity that was essentially independent of alkali concentration. No obvious difference between the adsorption capacity of a given paste for K+ and Na+ was observed. Adsorption of alkali ions in the pastes is considered to be caused by surface force which is related to the BET specific surface area of the paste, and charge compensation of C-S-H gel, mainly by electrostatic interactions. In C3S-nano SiO2 pastes mixed with alkali solutions, alkali ions may enter the structure of C-S-H gel to replace a part of Ca2+ in the interlayer. This assumption is supported by the structural characterization of C-S-H gel using 29Si MAS NMR.
AB - C3S pastes containing 0%, 5%, 10%, and 15% nano-SiO2 mixed with de-ionized water and alkali solutions were prepared. When C3S was completely hydrated, the pastes were ground into powders with a particle size less than 80 μm. Adsorption and desorption characteristics of alkali ions adsorbed by C3S-nano SiO2 pastes mixed with de-ionized water immersed in alkali solutions and those in C3S-nano SiO2 pastes mixed with alkali solutions, were investigated. Meawhile, the adsorption mechanisms of alkali ions were discussed. Results showed that the contents of alkali ions adsorbed by C3S-nano SiO2 pastes mixed with de-ionized water increased with increasing substitution levels of nano-SiO2 and/or the initial alkali concentrations. In C3S-nano SiO2 pastes mixed with de-ionized water, each paste was characterized by having a fixed alkali-adsorption capacity that was essentially independent of alkali concentration. No obvious difference between the adsorption capacity of a given paste for K+ and Na+ was observed. Adsorption of alkali ions in the pastes is considered to be caused by surface force which is related to the BET specific surface area of the paste, and charge compensation of C-S-H gel, mainly by electrostatic interactions. In C3S-nano SiO2 pastes mixed with alkali solutions, alkali ions may enter the structure of C-S-H gel to replace a part of Ca2+ in the interlayer. This assumption is supported by the structural characterization of C-S-H gel using 29Si MAS NMR.
KW - CS pastes
KW - adsorption
KW - alkali ions
KW - desorption
KW - nano-SiO
UR - http://www.scopus.com/inward/record.url?scp=85054324711&partnerID=8YFLogxK
U2 - 10.1007/s11595-018-1950-5
DO - 10.1007/s11595-018-1950-5
M3 - 文章
AN - SCOPUS:85054324711
SN - 1000-2413
VL - 33
SP - 1176
EP - 1185
JO - Journal Wuhan University of Technology, Materials Science Edition
JF - Journal Wuhan University of Technology, Materials Science Edition
IS - 5
ER -