摘要
The adsorption behaviors and dispersing properties of polycarboxylate superplasticizer(PCE) with different functional groups were systematically analyzed to reveal the theory and methods of modifying PCE molecular structures and regulating PCE performances. By substituting carboxylic groups with sulfonic groups, ester groups or acylamino groups, respectively, modified PCEs with different functional groups were synthesized. Results show that introducing low amount of ester groups or sulfonic groups into the PCE molecules has no negative effects on the fluidity of cement paste, while introducing acylamino groups into PCE molecules significantly weakens the fluidity of cement paste. At low amount(when the molar ratio of sodium methallyl sulfonate to TPEG is lower than 0.4), the rapid adsorption of sulfonic groups onto the cement particles contributes to the high dispersing performance of the sulfonic group modified PCEs. When the substitution ratio of acrylic acid by sulfonic acid is higher than 0.4, the viscosity and the yield stress of cement paste increases sharply. Redundant sulfonic groups lead to the excessive charge density of the PCE, which contributes to the inhomogeneous adsorption on the cement grains and hence results in the decline of the dispersing performance. Substitution of carboxylic group by acylamino group or ester group slightly changes the viscosity as well as the yield stress of cement paste. Introducing sulfonic group into PCE molecule improves the adsorption behavior of PCEs, while introducing ester group or acylamino group into PCE depresses the adsorption properties.
The adsorption behaviors and dispersing properties of polycarboxylate superplasticizer(PCE) with different functional groups were systematically analyzed to reveal the theory and methods of modifying PCE molecular structures and regulating PCE performances. By substituting carboxylic groups with sulfonic groups, ester groups or acylamino groups, respectively, modified PCEs with different functional groups were synthesized. Results show that introducing low amount of ester groups or sulfonic groups into the PCE molecules has no negative effects on the fluidity of cement paste, while introducing acylamino groups into PCE molecules significantly weakens the fluidity of cement paste. At low amount(when the molar ratio of sodium methallyl sulfonate to TPEG is lower than 0.4), the rapid adsorption of sulfonic groups onto the cement particles contributes to the high dispersing performance of the sulfonic group modified PCEs. When the substitution ratio of acrylic acid by sulfonic acid is higher than 0.4, the viscosity and the yield stress of cement paste increases sharply. Redundant sulfonic groups lead to the excessive charge density of the PCE, which contributes to the inhomogeneous adsorption on the cement grains and hence results in the decline of the dispersing performance. Substitution of carboxylic group by acylamino group or ester group slightly changes the viscosity as well as the yield stress of cement paste. Introducing sulfonic group into PCE molecule improves the adsorption behavior of PCEs, while introducing ester group or acylamino group into PCE depresses the adsorption properties.
作者
HE Yan
ZHANG Xiong
WANG Yiting
KONG Yaning
JI Tao
SHUI Liangliang
WANG Xiaofu
WANG Haoren
何燕;ZHANG Xiong;WANG Yiting;KONG Yaning;JI Tao;SHUI Liangliang;WANG Xiaofu;WANG Haoren(School of Civil Engineering,Suzhou University of Science and Technology,Suzhou 215011,China;State Key Laboratory of Silicate Materials for Architectures,Wuhan University of Technology,Wuhan 430070,China;State Key Laboratory of Green Building Materials,China Building Materials Academy,Beijing 100024,China;Key Laboratory of Advanced Civil Engineering Materials of Education Ministry,Tongji University,Shanghai 201804,China;School of Architecture and Engineering,Nanjing Institute of Technology,Nanjing 211167,China;Shanghai Municipal Engineering Design Institute(Group)Co.,Ltd.,Shanghai 200092,China)
基金
Funded by the National Natural Science Foundation of China(No.51808369)
the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.18KJB560016)
the Opening Project of State Key Laboratory of Green Building Materials(No.YA-615)
the State Key Laboratory of Silicate Materials for Architectures(No.SYSJJ2018-09)
Science and Technology Project of Jiangsu Provincal Department of Housing and Urban-Rural Construction(No.2018ZD049)
the Natural Science Foundation of Suzhou University of Science and Technology(No.XKQ2018009)
