Mechanical Stresses Generated by Crystallization of Salts Inside Treated and Non-Treated Monumental Stones; Monitoring and Interpretation by Acoustic Emission / Microseismic Activity.

Abstract

AbstractThe 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.