ABSTRACT Portuguese tiles and embrechados rare colonial historical and artistic heritage capable of safeguarding the luso-bazilian cultural link over time. The inappropriate use of mortars to resettle these elements gives rise to diverse pathological manifestations. Therefore, this article aims to characterize mineralogical mortars used in ancient Brazilian restorations to ascertain their composition and the presence of cementitious material or other contamination. To this end, the microstructure of mortar samples from the Cloister of the Church and Convent of São Francisco (BA) and samples from the Bom Jesus of Martírios Church (AL) were mapped. In this way, the XRD, XRF and SEM/EDS methods were applied. The mortars originating from the construction period of the works (18th and 19th century), mostly made of lime, had a porous microstructure, presence of medium silicon content, absence of chlorine, high calcium oxide content and little contamination. Those from subsequent restorations, mostly cementitious, presented dense microstructure, medium aluminum oxide content, high silicon dioxide content, low to medium calcium oxide content and contamination. It is suggested, therefore, that there be continuous documentary recording of interventions throughout the useful life of the building, to evaluate the performance of practices and thus obtain data with a view to improving processes and readjusting materials. In this sense, preparing detailed reports on the condition of the work before, during and after rehabilitation becomes essential.
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