The Nonequilibrium Crystallization Force

TL;DR

This paper demonstrates that nonequilibrium effects significantly influence the forces exerted by growing crystals in geological processes, especially in large pores, challenging traditional equilibrium-based predictions.

Contribution

It introduces a physical model incorporating nonequilibrium kinetics and disjoining pressure, revealing size-dependent detachment of crystals from pore walls.

Findings

Crystallization force drops in large pores due to nonequilibrium effects.

Critical pore size depends on kinetic coefficient ratios, not thermodynamics.

Maximum pore size for sustained forces varies from micrometers to millimeters.

Abstract

The forces exerted by growing crystals on the surrounding materials play a major role in many geological processes, from diagenetic replacement to rock weathering and uplifting of rocks and soils. Although crystallization is a nonequilibrium process, the available theoretical prediction for these forces are based on equilibrium thermodynamics. Here we show that nonequilibrium effects can lead to a drop of the crystallization force in large pores where the crystal surface dissociates from the surrounding walls during growth. The critical pore size above which such detachment can be observed depends only on the ratio of kinetic coefficients and cannot be predicted from thermodynamics. Our conclusions are based on a physical model which accounts for the nonequilibrium kinetics of mass transport, and disjoining pressure effects within the thin liquid film separating the crystal and the surrounding walls. Our results suggest that the maximum size of the pores that can sustain crystallization forces close to the equilibrium prediction ranges from micrometers for salts to a millimetre for low solubility minerals such as calcite. These results are discussed in the light of recent experimental observations of the growth of confined salt crystals.