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Temperature-induced heteroaggregation in polydisperse portlandite suspensions

Published

Author(s)

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

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 (IEP). 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 enhancement of heteroaggregation (i.e., of polydisperse Ca(OH)2 particulates; "aggregation" hereafter) due to the diminution of electrostatic repulsive forces at elevated temperatures. The temperature dependence of the suspension viscosity is further shown to diminish with increasing particle volume fraction as a result of of volumetric crowding and the formation of denser fractal structures in the suspension. Significantly, the temperature-dependent rheological response of suspension is shown to be strongly affected by the suspending medium's properties, including ionic strength and ion valence, which affect aggregation kinetics. These data provide insights into heteroaggregation processes that may affect the temperature-dependent rheology of portlandite-based, and similar suspensions.
Citation
Langmuir
Volume
36

Keywords

rheology, activation energy, interaction potential, aggregation, fractal structuring

Citation

Garboczi, E. , Sant, G. , Mehdipour, I. , Neithalath, N. , Bauchy, M. , Srivastava, S. and Kandy, S. (2020), Temperature-induced heteroaggregation in polydisperse portlandite suspensions, Langmuir, [online], https://doi.org/10.1021/acs.langmuir.0c01798 (Accessed April 24, 2024)
Created August 17, 2020, Updated February 7, 2023