Temperature-Induced Aggregation in Portlandite Suspensions

Sharu Bhagavathi Kandy, Iman Mehdipour, Narayanan Neithalath, Mathieu Bauchy, Edward Garboczi, Samanvaya Srivastava, Torben Gaedt, Gaurav Sant

Research output: Contribution to journalArticlepeer-review

Abstract

Temperature is well known to affect the aggregation behavior of colloidal suspensions. This paper elucidates the temperature dependence of the rheology of portlandite (calcium hydroxide: Ca(OH)2) suspensions that feature a high ionic strength and a pH close to the particle's isoelectric point. In contrast to the viscosity of the suspending medium (saturated solution of Ca(OH)2 in water), the viscosity of Ca(OH)2 suspensions is found to increase with elevating temperature. This behavior is shown to arise from the temperature-induced aggregation of polydisperse Ca(OH)2 particulates because of the diminution of electrostatic repulsive forces with increasing temperature. The temperature dependence of the suspension viscosity is further shown to diminish with increasing particle volume fraction as a result of volumetric crowding and the formation of denser fractal structures in the suspension. Significantly, the temperature-dependent rheological response of suspensions is shown to be strongly affected by the suspending medium's properties, including ionic strength and ion valence, which affect aggregation kinetics. These outcomes provide new insights into aggregation processes that affect the temperature-dependent rheology of portlandite-based and similar suspensions that feature strong charge screening behavior.

Original languageEnglish (US)
Pages (from-to)10811-10821
Number of pages11
JournalLangmuir
Volume36
Issue number36
DOIs
StatePublished - Sep 15 2020
Externally publishedYes

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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