Title: SEM-EDS analysis of adscititious layers in partitions historical buildings

Abstract

The aim of the study was a qualitative analysis of the composition of adscititious layers in partitions historic buildings, taking into account the differences in the microstructure of the tested composites. Representative material samples were taken for the tests, all of them were taken from the historical structural fragments of brick walls of the Bishop's Castle and the Roman Catholic Church of St. John the Baptist in Janow Podlaski. The samples were dried at room temperature and then placed on a carbon tape. In the surface and point analyzes, an accelerating voltage of 15 kV was used, the samples were not sputtered with conductive material. Based on the results of SEM-EDS analyzes for various areas of the studied samples of supplementary material, it can be concluded that the main elements included in the tested samples are: silicon, carbon, calcium, as well as aluminum, iron, potassium and magnesium. In addition to the exchangeable elements, the material tested also contained small amounts of sodium, sulfur and chlorine. The Hitachi TM3000 scanning microscope was used to determine the chemical composition in the micro-area of the main mineral components of the examined supplementary layers, equipped with a chemical composition analysis system based on X-ray energy dispersion - EDS by Swift ED 3000 Oxford Instruments. The elemental composition of the samples taken is a consequence of the chemical composition of the original clay deposits used to make the brick. The oxide composition of such deposits is: Al2O3, SiO2, Fe2O3, MgO, CaO, Na2O and K2O. A significant amount of silicon and aluminum was due to the presence of aluminosilicates, the main material of brick clay. The presence of iron confirmed the presence of oxides of this metal in the composition of the supplementary layers, mainly Fe2O3, giving the material a characteristic brown-red color. The uniform presence of most elements (except S, Na) in the complementary layer indicated a similar elemental composition of the complementary layer with the parent material. The particle distribution of most elements coincided with each other. Directly in the supplementary layer, more calcium and a smaller amount of silicon were visible, which may indicate that it was a separate technological layer, but with a similar composition to the substrate.