Durability tests on sandstones

The sandstone is widely used as cladding stone, even in historic building. Its decay its commonly associated with the action of salts or with sulphation in polluted conditions. In fact, in many cases, the decreasing of mechanical properties under the action of salt crystallization and SO2 is higher than the one induced by frost and by thermal shock action. The results of durability tests performed in laboratory or coming from literature data, referred to sand-stones even with differences in petrographic and mineralogical properties, are analysed. Three durability tests are object of this study: the determination of resistance to salt crystallisation according to EN 12370, the resis-tance to ageing by SO2 action in the presence of humidity according to EN 13919, the determination of frost resistance according to EN 12371. The evaluation of the decay degree has been performed by means of de-structive and non destructive tests, with further investigation than required by the standards, to evaluate which property (physical or mechanical) is more suitable to detect the weathering on this kind of rock. Often the method to evaluate the decay forecast by the standards does not underline the real alteration occurred in the stone sample, while other measurements of different characteristics do it. For example the mass weighing difference is not always satisfactory to appreciate the decay of the stone after salt crystallization while the water absorption, well correlated with the physical mechanical characteristics of the stones, together with visual inspection, is a good index of the decay for a distinction, in terms of durabil-ity, between different sandstones even of a same geological district.