The Physical Basis of Frost Weathering: Toward a More Fundamental and Unified Perspective

Abstract

Frost weathering of rock is widely held to be related fundamentally to the volumetric expansion of pore water during freezing. This hypothesis is in fact at odds with much of the work on freezing of soils and porous building materials; freezing-induced damage in these materials is strongly related to water movement and often unrelated to specific-volume change of the pore fluid during freezing. Not surprisingly, the traditional view of the mechanics of frost weathering leads to predictions, such as the existence of a “critical degree of saturation,” that are contradicted by some freezing experiments conducted on rocks. Working within the traditional framework, it is also difficult to explain in a self-consistent fashion the observed importance of freeze-thaw cycling. We elaborate on these and other objections to the volumetric-expansion hypothesis, and suggest how fundamental considerations of the thermodynamics of water and ice in porous media, and of the fracture-mechanical behavior of rock, can lead to a unified view of frost-weathering.