Effects of β-Cyclodextrin Modified PCE on Rheological and Hydration Performance of Cement Paste
In order to systematically investigate β-cyclodextrin(β-CD)modified polycarboxylic acid superplasticizer(PCE),the β-CD/HPEG inclusion compound was obtained by modifying HPEG monomer with β-CD,and then the β-CD/HPEG inclusion compound partially replaced HPEG to synthesize polycarboxylic acid superplasticizer.The dispersing performance as well as their effects on cement hydration process was investigated.The results showed that the insertion of β-CD into the side chain performed higher steric hindrance effect.The dispersing performance of β-CD modified PCE varied with the insertion ratio of β-CD modified HPEG.And the dispersion force of β-CD modified PCE was caused by the steric hindrance formed by the structure of β-CD modified PCE and the electrostatic repulsion produced by-COO-and-OH groups adsorbed on cement surface.β-CD modified PCE exhibited enhanced retardation effect on cement hydration,resulting in prolonged induction period,decreased hydration products at early age.But,due to the enhanced dispersing performance of β-CD modified PCE,the hydration degree was promoted at 28 d,resulting in more hydration products formed in the matrix.
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