Rheophysics of pastes: a review of microscopic modelling approaches

Abstract

Pastes are materials intermediate between solids and liquids which are of great practical interest as they keep the shape they have been given. Despite their various internal structures it is possible to draw up a generic rheophysical scheme from which one qualitatively understands, from a physical point of view, their main mechanical characteristics, i.e. solid regime, solid-liquid transition, liquid regime, thixotropy and aging. Here we review in detail these different properties as they are generally observed with most pasty materials and the attempts to describe them using microscopic structure-based theoretical models. For real systems a unified, qualitative, conceptual description is provided. For some model systems (e.g., foams, colloidal gels...) there exist consistent microscopic approaches providing quantitative relationships between rheological parameters in the solid regime and physical parameters of the system. For the liquid regime and thixotropy the situation is more complex.

Rheological study of mudflows at Lianyungang in China

“…Knowledge of these properties is important to assess the sensitivity to fluidization and erodibility, the damping of turbulence and the prediction of density currents and fluid mudflow. The rheology of sediment and water mixtures was discussed in detail by Berlamont et al (1993) for the marine sediment transport and by Coussot (1997Coussot ( , 2007 for the mudflow, respectively. Overall, at low sediment concentrations, the mixtures usually exhibit Newtonian fluid behavior, while at high sediment concentrations the mixtures become non-Newtonian shear-thinning or viscoelastic behaviors.…”

A laboratory study of rheological properties of mudflows in Hangzhou Bay, China

“…), dynamic rheological data for natural mud are rare-the published data for the rheological properties of mud motions focused primarily on the rheology of steady mudflows. (Coussot (1997) for excellent reviews on current knowledge in non-oscillatory mudflows, and Coussot (2007) for a review on rheology for both steady and oscillatory mudflows.) Published data on dynamic rheology of natural mud are rare.…”

Um Modelo Constitutivo Fenomenológico Irreversível Para Descrição Reológica De Pastas De Cimento

“…Neste sentido, a perturbação mínima é análoga a tensão limite (yield stress). A existência da tensão limite implica na transição entre sólido-líquido, em geral as pastas enquadram-se neste cenário (22,77).…”

“…A Dinâmica de Partículas e principalmente a Mecânica Estatística são ferramentas utilizadas neste tipo tratamento (77,83,84), através do emprego de funções de correlação obtém-se informações em nível macroscópico, como tensão limite e módulo de rigidez (77,84). Diferentes teorias são exploradas na abordagem microscópia, entre elas:…”

“…Por definição, todo dado coletado para compor uma curva de escoamento deve corresponder ao regime permanente (77). Entretanto, para pastas de cimento, é difícil ou impossível atingir o regime permanente, devido as reações químicas presentes (hidratação).…”