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Advanced Construction Materials and Technologies
of such minerals as ilmenite (FeTiO3) and dusty magnetite (FeO·Fe2O3).
Fig. 1. Dependence of the area of red inclusions
at the surface of labradorite samples on the
temperature of heating
deposit No. 1 – Ocheretyansky; deposit No. 2 – Neviryvsky; deposit No. 3 – Osnikivske; deposit
No. 4 – Katerinovsky
The results of this study provide an opportunity to compare labradorite deposits and evaluate the content of Fe2+-elements in minerals. That would help selecting construction materials from labradorite for exterior cladding of buildings. Since at natural temperatures the oxidation of Fe2+- elements occurs in labradorite over time under the influence of aggressive environments, red stains emerge at the surface.
Estimation of velocity of ultrasonic wave propagation in samples at labradorite heating. In the temperature range of 200–400 °C, labradorite demonstrates the disclosure of previously existing microcracks (Fig. 2). The most significant changes occur in a range from 500 to 600 °C, where there is an increase in pore openness. This is due to the formation of gaps between minerals, and merging the breaks with open pores. These phenomena are caused by the anisotropy of natural stone. The dependence of propagation velocity of ultrasonic wave on temperature is almost the same in labradorite samples. A decrease in the ultrasonic wave velocity by 80 % of the initial values occurs when heating the samples to a temperature of 900 °C. At a temperature of 700– 900 °C, most labradorite samples demonstrate a decrease in the velocity of ultrasonic wave. This is explained by that the number of cracks in the studied samples reaches a threshold value. A change in the velocity of ultrasonic wave propagation in labradorite samples under the influence of temperature is nearly the same for all represented deposits.
4. Conclusions:
• Digital processing of images of labradorite samples has shown that the oxidation of minerals
containing Fe2+ occurs permanently. At temperatures up to 600 °C, this process proceeds
slowly in most labradorite samples. At a temperature above 600 °C, the oxidation of metals
occurs more intensively. Red spots at the surface of samples is the result of oxidation of metal
2+
compounds Fe , at various deposits of labradorite they cover a different area of the sample’s
surface of natural stone, which varies within 39‒60 %.
• The dependence of ultrasonic wave propagation velocity in labradorite samples on temperature is almost the same. On average, there is a decrease in the ultrasonic wave velocity by 80 % of the initial values when samples are heated to a temperature of 900 °C. At a temperature of 700–900 °C, most labradorite samples demonstrate a decrease in the ultrasonic wave velocity. This is explained by that the number of cracks in the examined samples reaches a threshold value.
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Fig. 2. Dependence of ultrasonic wave propagation velocity in labradorite samples on temperature, sample from