ABSTRACT
The resistance of natural stones to decay not only concerns a worsening of its aesthetical properties, but also and above all a decrease in its mechanical strength. The comparison of results of artificial ageing tests, executed in a laboratory with long-term natural weathering, is useful for the study of the behavior of natural historical building stone elements. Three different kinds of stone, that is, marble, gneiss and granite, have been tested by means of two different artificial weathering tests: determination of the resistance to ageing by means of thermal shock and freeze and thaw cycles. The in situ marble building elements have shown different signs of decay, while the granite and gneiss have shown ruptures and defects, mainly as a result of erroneous project calculations or installations. In laboratory instead marble seem to be more sensible to thermal shock and freeze-thaw action than in situ, while gneiss and granite are resistant to ageing tests.
