Crystallization pressure

The weathering of rocks due to salts, known as haloclasty, can be linked to three types of processes: crystal growth in confinement, thermal expansion and crystal hydration. Nevertheless, the main mechanism that explains this damage is related to the crystallization pressure. This chapter discusses the concept of crystallization pressure and its relation to disjoining pressure. In the Correns equation, the crystallization pressure exerted by a salt crystal is simply related to the degree of supersaturation of the solution in which it grows. The disjoining pressure opposes the contact between the crystal and the wall by maintaining the liquid film. The disjoining pressure therefore sets an upper limit to the crystallization pressure. The chapter also details direct measurements of the force exerted by the spontaneous precipitation of a salt microcrystal during evaporation in confinement, like that found in porous materials.