Rock salt is considered as a pure aggregate of halite (mineral NaCl) crysta
ls and its behaviour is investigated by a micro-macro approach. The behavio
ur of the polycrystalline aggregate is deduced from the properties of the c
onstituent halite crystals. A model For the elastoplastic behaviour ui hali
te crystal has been deduced from experimental data available in the literat
ure. The basic equations of the micro-macro model for the polycrystalline m
edium and the calculation method are then presented and the elastoplastic b
ehaviour of rock salt is investigated by this method. The hardening effects
obtained for the polycrystal are found to be very different from those obt
ained for FCC metal polycrystals. The differences are explained as a conseq
uence of differences of families of glide systems in these crystals. Finall
y, the internal stresses in the polycrystal are studied in order to elucida
te the origin of cracking and damage of the rock salt. (C) 2000 Editions sc
ientifiques et medicales Elsevier SAS.