Abstract:
This recommendation is devoted to testing the resistance of natural stone and fired-clay brick
units against salt crystallization. The procedure was developed by the RILEM TC 271-ASC to evaluate the
durability of porous building materials against salt crystallization through a laboratory method that
allows for accelerated testing without compromising the reliability of the results. The new procedure is
designed to replicate salt damage caused by crystallization near the surface of materials as a result of
capillary transport and evaporation. A new approach is proposed that considers the presence of two stages in
the salt crystallization test. In the first, the accumulation stage, salts gradually accumulate on or near the
surface of the material due to evaporation. In the second, the propagation stage, damage initiates and
develops due to changes in moisture content and relative humidity that trigger salt dissolution and
crystallization cycles. To achieve this, two types of salt were tested, namely sodium chloride and sodium
sulphate, with each salt tested separately. A methodology for assessing the salt-induced damage is
proposed, which includes visual and photographical observations and measurement of material loss. The procedure has been preliminarily validated in round robin tests.
