Caracterização de argamassa antiga: Estudo de caso: casa amarela - Unidade Municipal de Educação Infantil - UMEI Timbiras

Abstract

This dissertation addresses some of the theories, principles and criteria for the conservation, rehabilitation and restoration used during the intervention on old buildings. It deals on the major types of coatings used in mortars until the end of the twentieth century. The mortars are studied based on their constitution and properties that determine their performance, in particular, the lime-based mortars. It includes the case study of the Casa Amarela (Yellow House), a building of the late nineteenth century, located in Belo Horizonte City, which has been restored to house an unit of Municipal Kindergarten named UMEI Timbiras. An experimental study was developed to characterize the mortar lining of this old building aiming to support future interventions/proposals for a mortar recovery compatible in terms ofphysical, chemical and mechanical properties with the original mortar. From analyses of samples of the old mortar coating, removed during the restoration work, it was possible to identify its composition. The characterization of this ancient mortar has been performed based on microstructure, physical, chemical and mineralogical analyses. The old mortars specific surface area by the Brunauer-Emmett-Teller (BET) method yielded a relatively low value, which contributes to exclude the possibility of the presence of clay in the sample. Accordingly, the sample showed a small volume of pores in the lower range of mesopores. The microstructure studies were performed mainly by scanning electron microscopy with a strong support of EDS microanalysis (SEM-EDS), but also with important contribution of the stereoscopic microscope. To identify the chemical and mineralogical composition of the mortar, other techniques were used: X-ray fluorescence (XRF) chemical analysis, X-raydiffraction (XRD), infrared spectrometry (FTIR) and thermogravimetric analysis (TG). The following phases have been found: quartz (SiO2), calcite (CaCO3) and microcline (KAlSi3O8). Guided by the SEM images, it was possible to select suitable microareas in the sample for EDS semiquantitative chemical analyses. All these results indicated that it is a lime-based mortar without the presence of Portland cement or additions of organic materials.