IMPACTS OF FIRE ON HISTORIC STONE MASONRY STRUCTURES: PHYSICOCHEMICAL ANALYSIS AND APPLICATION TO THE AL-MUSAFIRKHANA PALACE (CAIRO)

Abstract

The current paper investigates the influence of fire on historic stone masonry structures, for the purpose to assess stones structures deterioration, based on non-destructive measurements for significant changes in the physical properties and mineralogical composition of limestone. Different cubic samples of limestone used in historic buildings، were selected and subjected to increasing temperatures, from room temperature to heating at 200°C, 400°C, 600°C, 800°C in the oven for a period of 6 hours. The induced changes in the microstructure, petrophysical and mechanical properties of the limestone were examined and correlated with The petro-graphic analyses (polarizing microscope, XRD, SEM) and physical parameters (density, porosity, water ab-sorption), mechanical properties (uniaxial compressive strength). Results showed that fires and high temper-atures cause significant changes in the physical properties and mineralogical composition of limestone، par-ticularly at temperatures beyond 300oC, produces considerable microcracking and causes colour changes in limestone. The developed cracks act to increase the porosity and significant reduction in compressive strength in limestone. The study included the methods of treatment through for the use of some consolidation materials (Paraloid B72) mixed with nanocomposites in the process of consolidation. Results showed demonstrated the superiority of the Paraloid B72 mixed with Nano calcium hydroxide in the consolidation and filling the spaces between the mineralogical composition for building stones. The results of this paper indicate that the deterio-ration of limestone depends on mineralogical composition and fabric. The consideration of mineralogical com-position and rock fabric parameters, however, helps provide a more comprehensive evaluation and interpre-tation limestone damage.