Microstructural Changes in Lime Mortars of Ancient Brick Masonries

The results of studying the recrystallization of calcite in lime mortars of ancient brickwork, associated with the mechanism of transformation of portlandite, which originally constituted the basis of lime mortar, into calcite, are presented. It has been established that under natural conditions this process takes from 100 to 200 years. Examples are given showing that portlandite is completely transformed into calcite in masonry solutions of the 18th century. The study of the fine fraction of newly formed calcite, with a grain size of up to 5 microns, by X-ray diffraction methods, makes it possible to determine the degree of relative recrystallization of calcite. This is done based on the estimate of the peak width at half height (FWHM) for its main reflection from the plane – 3.03 Å, which allows using these data to estimate the relative age of brick and masonry of various monuments of architectural heritage. Factual data are presented, confirming that the degree of recrystallization of calcite in older lime solutions is significantly higher than in younger ones. The use of the proposed considered method for the relative assessment of the age of brick and masonry is especially important for the South of Russia, where many objects characteristic of the northern provinces of the Byzantine oikumene and other cultures erected using lime mortars have survived.

V.D. KOTLYAR¹, Doctor of Sciences (Engineering) (This email address is being protected from spambots. You need JavaScript enabled to view it.),
V.V. PISHCHULINA¹, Doctor of Architecture (This email address is being protected from spambots. You need JavaScript enabled to view it.);
Yu.V. POPOV², Candidate of Sciences (Geology and Mineralogy) (This email address is being protected from spambots. You need JavaScript enabled to view it.);
B.V. TALPA², Candidate of Sciences (Geology and Mineralogy) (This email address is being protected from spambots. You need JavaScript enabled to view it.)

¹ Don State Technical University (1, Gagarin Square, 344000, Rostov-on-Don, Russian Federation)
² Southern Federal University (105/42, B. Sadovaya Street, Rostov-on-Don, 344006, Russian Federation)

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