Influence of the Structural Modification of Polycarboxylate Copolymer with a Low Dispersing Ability on the Set-retarding of Portland Cement

Two structurally modified polycarboxylate (PC) copolymers were synthesized to explore the influence of structural modification with these polymers on the set-retarding of Portland cement. The dispersion ability of these polymers was eliminated by introducing very short graft side chains. The synthesized copolymer structures were verified by fourier transform infrared spectroscopy (FTIR), GPC and proton nuclear magnetic resonance ¹H NMR analyses. The initial and final setting times, polymer adsorption capability, strength development, paste fluidity, and x-ray diffraction (XRD) of hardened pastes were tested. The test results indicate that the PC copolymers do not increase the cement paste fluidity due to their short graft side chain length, while a significant set-retarding effect is observed when the polymer structure is highly anionic, with the set-retarding effect increasing linearly with polymer dosage up to 1%. The adsorption of copolymer on cement grains rapidly reaches saturation within 5 minutes after mixing for both polymers. Adding these PC copolymers does not noticeably change the early strength development, although the polymers selectively affect the hydration behavior of C₃S and C₂S at very early ages. Early hydration of groups, such as C₃S, C₂S, C₃A and C₄AF, is not likely to be significantly involved in the mechanism by which carboxylate copolymers with very short graft chains delay cement setting.

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    • © Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg 2015
  • Authors:
    • Jun, Yubin
    • Jeong, Yeonung
    • Oh, Jae Eun
    • Park, Jongnam
    • Ha, Ju-hyung
    • Sohn, Seok Gyu
  • Publication Date: 2015-9

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  • English

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  • Accession Number: 01633017
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 28 2017 10:40AM