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Investigation of Plasticizing and Slump Retaining Properties of
PEG-Based Tri-Block Copolymers in Cementitious Systems

Doroudian, Mohadese | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43498 (03)
  4. University: Sharif University of Technology
  5. Department: Chemistry
  6. Advisor(s): Pourjavadi, Ali
  7. Abstract:
  8. Plasticizers in cementitious systems are additives that upon addition at a low dosage can change the workability, mechanical strength and other properties of cement paste effectively. In this study, tri-block copolymers based on poly ethylene glycol (PEG) was synthesised and their applications in the cementitious systems investigated. The main purpose is the verification of plasticizing effects of these copolymers in the cement paste. ABA tri-block copolymers with PEG (1000 and 1500 g/mol) as B block, poly caprolactone, poly caprolactam, poly lactide and poly glycolide (with different weight ratio) as A block were synthesised via ring opening polymerization with stannous octanoate as catalyst. The poly citric acid and poly tartaric acid as A block were synthesised with esterification reaction by the elimination of the produced water. In the second section of the project, the plasticizing effects and rheological propertiesof the samples was studied by mini-slump test and cylinder-cup rheometer. The Results show that by adding some of these copolymers to the cement paste, the flowability increases. The copolymers of citric acid disperse the cement particles more effective than the other copolymers because of the existence steric hindrance rather than electrostatic repulsion. For tartaric acid, citric acid and their copolymers the time of setting of hydraulic cement were also determined by Vicat Needle instrument. Finally the rheological parameters of the cement paste were determined with Bingham and Herschel-Bulkley models for quantifying study of flowability of cement paste upon addition of the synthesised plasticizers.
  9. Keywords:
  10. Polyethylen Glycol (PEG) ; Cementitious Systems ; Triblock Copolymer ; Plasticizing Effect ; Slump ; Rheological Parameters

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