Physical weathering of building stones induced by freeze-thaw action: a laboratory long-term study

Damages to natural building stones induced by the action of frost are considered to be of great importance. Commonly, the frost resistance of building stones is checked by standardised freeze-thaw tests before using. Corresponding tests normally involve 30-50 freeze-thaw action cycles. In order to verify the significance of such measurements, we performed long-term tests on four selected rocks over 1,400 freeze-thaw action cycles. Additionally, numerous petrophysical parameters were analysed to compare the behaviour of rocks in the weathering tests according to the current explanatory models of stress formation by growing ice crystals in the pore space. The long-term tests yield more information about the real frost sensibility of the rocks. A clear deterioration cannot be determined in most cases until 50 weathering cycles have been completed. In the freeze-thaw tests, the samples are also stressed by changing temperature and moisture, indicating that different decay mechanisms can interfere with each other. Thus, thermohygric and moisture expansion are important damage processes.