The influence of the humidity on the decay of marbles

The effect of humidity on the weathering of marbles with different petrographic fabric, has been pointed out performing two different kind of accelerated ageing test methods: thermal cycles and hydric expansion. In the first test, the stone specimens have been subjected to variations of temperature from -10°C to +70 °C both in dry and wet conditions. The loss in flexural strength and the increase of water absorption has been evaluated on set of 5 specimens for each step of ageing. In the second test the tendency to expansion of the marbles placed in a water tank heated until 80°C has been measured. The results show the influence of humidity on the loss of mechanical resistance of marble, but the different resistance to ageing among the same kind of stone (all calcite made) is strictly related to the habit of the crystals. The tests are part of the program work of the European Project TEAM ("Testing and Assessment of Marble and Limestone") belonging to the EU - DG XII GROWTH program.