Growth and Dissolution of Crystal under Load: New Experimental Results on KCl

Abstract

From the first experiments of Lavalle in 1853, it has been concluded, following Taber and Correns’s publications, that a growing crystal can exert a linear pressure. This pressure has long been accounted for the stone degradation by salt crystal, as observed on cultural heritage objects. Nevertheless, according to both Riecke’s principle and crystal growth theories, a mechanically constrained crystal has a higher solubility than an unstressed one; since the local supersaturation is reduced, the loaded faces may dissolve whereas the crystal still grows along the unloaded faces. In view of these contradictory predictions, we performed new experiments of loaded KCl crystal growth under strictly controlled conditions, with accurate measurement devices. We show that (1) the loaded crystal immersed in a slightly supersaturated solution dissolves along the loaded faces and grows along the unloaded ones, (2) the dissolution rate depends on the topology of the loaded face, and (3) the crystal is not able to grow against any applied pressure nor to develop any “crystallization pressure”. These results verify Riecke’s principle and contradict Taber’s and Correns conclusions and related experiments. Therefore we also discuss the artifacts which were identified during our experiments and have not been monitored in these reference works.