salt weathering

(geology) The granular disintegration or fragmentation of rock material produced by saline solutions or by salt-crystal growth.

A form of weathering, especially important in hot deserts, which combines physical weathering (crystal growth) with some chemical weathering (hydration). When saline solutions in rock pores and joints begin to crystallize, stresses are set up within the rock, and surface flaking or granular disintegration result.

The salts concerned may come from earlier chemical weathering or may have been carried inland from the sea by spray, snow, or rain. Salt weathering arising from saline groundwater also attacks built structures in arid lands; concrete, in particular, is liable to disintegration, so that foundations which penetrate to zones near the groundwater need special sheathing, and cement must be salt-free. Salt blisters, which form under thin, heat-attracting, bitumen surfaces like roads, car parks, and runways, can heave the surface into small domes, or cause cracks to develop.