The crystallization of salts in building stones is one of the most common and severe deteriorating phenomencndeveloped on Historic Buildings. To evaluate their mechanical effects in treated and non-treated stones, experimental salt crystallization tests and the monitoring of the corresponding acoustic emission / microseismic activity, AE/MS, have been planned.
Salt crystallization tests have therefore been performed on a high porosity (30%) limestone used in the building of the Cathedral of Murcia (Spain). Each test consisted of 11 and 20 cycles (for the non-treated and treated specimens, respectively) of immersion of specimens in salt solution (14% Na2SO4. 10H2O) for 4 h., drying in an oven at 60 °C for 14 h. and final cooling at room temperature for 6 h. The treated specimens were consolidated by total immersion in ethyl silicate -Tegovakon V- and protected with a water repellent, oligomeric polysiloxane -Tegosivin HL- 100-, (both from Th. Goldschmidt, FRG).
The AE/MS, was monitored in the 100-300 KHz range. The preliminary results show a very different AE/MS behaviour between the non-treated and the treated specimens.