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minerals as pyroxene and magnetite to Fe
total area of the sample, it was found that the area of red spots in the labradorite samples (Fig. 1) increased when heated to 300 °C. For example, for the Ocheretyansky labradorite, from 0.91 % to 4 %, for the Osnikivske labradorite, from 1 % to 3 %, and for other samples from deposits the growth amounted to 1 %. At a temperature of 400 °C, one observes an increase in red spots in labradorite samples from the Osnikivske deposit by 2.7 times, from 3 to 8 %. A sharp increase in red spots was observed in labradorite samples from the Ocheretyansky deposit at a temperature of 600 °C. At 900 °C, red spots cover the surface of the samples by 39 to 60 % of the area. The spots manifested themselves the least on labradorite samples from the Neviryvsky and Katerinovsky deposits, by 41 and 39 %, respectively. Red spots were most visible on labradorite samples from the Ocheretyansky and Osnikivske deposits by, respectively, 60 and 46 %, due to a higher content
New Trends in Green Construction
INFLUENCE OF HIGH TEMPERATURES ON PHYSICO-MECHANICAL AND DECORATIVE PROPERTIES OF LABRADORITE
Valentyn Korobiichuk , Oleksandr Sydorov, Iryna Leonets, Viktor Kravets, Stanislav Stovpnyk
1. Introduction
The ventilated facades that are decorated by natural stone are widespread. Although the natural stones are non-combustible materials, the effect of fire and heat can cause irreversible changes to their structure and physical-mechanical properties that influence the durability and static behavior of stone-made structures. Following a fire in buildings, there is an issue related to the renovation of these facilities. In this case, it is necessary to take into consideration the change in the physical- mechanical and decorative properties after exposure to high temperatures.
2. Material and methods
We studied the influence of heat treatment on the physical-mechanical properties of large-grain labradorite from Ukraine, which has a violet irisation of labrador grains. We experimentally examined samples from the four fields of labradorite, every deposit of labradorite was represented by 4 samples.
Samples of labradorite were heated in a furnace at a rate of 1 °C/min to the nominal temperature. A low rate of rise in temperature is used to maximize the temperature effect. The samples were heated in the electrical furnace to 200, 300, 400, 500, 600, 700, 800, 900 °C, followed by cooling to a temperature of 20 °C.
The front surface of labradorite samples was digitized using the Canon scanner CanoScan LiDE 700F. To determine the strength of natural stone and patterns in the development of cracks, we measured (in a stone sample) the velocity of surface ultrasonic wave propagation using the ultrasonic device UK-14MP, which is equipped with a surface sound sensor with a fixed base of 120 mm. We measured the propagation of ultrasonic waves along the diagonals of samples; the data acquired were averaged.
3. Results
Determining the surface area of the sample occu-pied by the oxidized metal at labradorite heating. The heating of labradorites led to the emergence of red spots at the polished surface of samples. This is explained by a phase transformation of crystals and the oxidation of Fe2+-elements in such
3+
. When computing the area of red spots relative to the
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