Rate of thixotropic rebuilding of cement pastes modified with highly purified attapulgite clays

Shiho Kawashima*, Mohend Chaouche, David J. Corr, Surendra P. Shah

*Corresponding author for this work

Research output: Contribution to journalArticle

46 Scopus citations

Abstract

This study investigates the influence of highly purified, nano-sized attapulgite clays on the rate of structural rebuilding of cement pastes. A shear rheological protocol is implemented that measures the rate of rebuilding of pastes after being broken down under shear and maintained under stress corresponding to the weight of the material. This simulates a real casting situation during which the concrete is initially in motion, then cast in place and measures how quickly it gains green strength immediately after placement. The rate of recovery for different resting times and preshear conditions are considered. The strain rate decay curves are fitted with a compressed exponential model to obtain relaxation time. The results show that the purified attapulgite clays significantly accelerate rate of recovery of pastes, especially at early ages. However, this accelerating effect diminishes at longer resting times as hydration mechanisms begin to dominate.

Original languageEnglish (US)
Pages (from-to)112-118
Number of pages7
JournalCement and Concrete Research
Volume53
DOIs
StatePublished - Jul 16 2013

Keywords

  • Clay (D)
  • Formwork pressure (E)
  • Oscillatory shear (B)
  • Rheology (A)
  • Thixotropy (C)

ASJC Scopus subject areas

  • Building and Construction
  • Materials Science(all)

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