Abstract

The aim of this study is to evaluate how the ambient temperature and salt concentration affect the salt decay of a sedimentary stone. Samples of a detritic limestone which have experienced cycles of accelerated ageing at 5, 25 (room temperature, RT) and 50 °C with brines which had different sodium sulphate concentration were analysed. The weight of the samples and of the pieces fallen off during the cycles was monitored. The results show that the damage is more important at 5 °C than at RT. The samples at 50 °C were intact at the end of the experiment. Second, the size of the pieces fallen from the samples is significantly smaller for low temperatures: at 5 °C, the decay produces a fine powder; at RT, the pieces fallen off are of millimetre to centimetre scale. The weathering patterns are therefore different at these two temperatures: fine crumbling at 5 °C; coarse crumbling and contour scaling at RT. The salt uptake seems quite similar for a given concentration whatever the temperature. The decay also seems to be of a different kind for each concentration at RT: crumbling at low concentration, contour scaling at high concentration. Crystallization seems to take place deeper inside the porous network of the stone when the concentration of salts in the brine is higher, that is to say when the brine viscosity is higher.