ESTIMATING MAXIMUM TEMPERATURES ATTAINED DURING FIRES IN BUILDING STONEWORKS BY THERMOLUMINESCENCE: A CASE STUDY FROM UNCASTILLO, SARAGOSSA (SPAIN)

Abstract

Knowing the maximum temperatures attained by stonework during past fires in historical buildings is important to understand the damage caused to the materials and the subsequent weathering history after the fire. Thermoluminescence (TL) provides a tool to assess such temperature but different protocols exist. TL has been tested to assess the maximum temperature reached by a past fire on the surface of calcitic sandstone (frequently used in historical buildings in Saragossa, Central Eastern Spain). We have prepared subsamples of this sandstone annealed from 200°C to 700°C. Quartz extracts from such samples were used for testing different TL protocols, from measuring the erosion of the whole TL glow curve of quartz extracted to test the Thermal Activation Characteristic (TAC) and other more recent approaches, such as comparing the sensitization of the integrated 110, 200 and 250-400°C peaks at different irradiation doses or a full predose protocol. The erosion of the TL glow curve of quartz seems to underestimate the attained temperature while the other tested protocols indicate that the temperature reached was 400°C.