Modification of basalt fibers to improve operational efficiency in aggressive environments

DOI: 10.62564/M4-ID9285

Iryna Diduk¹, Yurii Chuvashov¹, Olga Yashchenko¹, Nataliya Koshelenko¹, Ganna Grytsak<sup>2

1</sup>Frantsevich Institute for Problems of Materials Science National Academy of Science of Ukraine
²SE STC "Basalt-fibre materials" IPM NAS of Ukraine


The use of basalt fibre as a reinforcing element, including in cement-concrete compositions, is increasing. However, the surface layer of fibers is dissolved during long-term use in the cement matrix, which is associated with cement hydration. Increasing the corrosion resistance of basalt fibers can be achieved by modifying the fibers by heat treatment. The influence of the temperature and processing time of basalt fibers on the chemical stability of fibers in alkaline and acidic environments is studied. For the experiment, fibers with a surface area of 5000 cm2 were taken and kept in solutions of 2N NaOH and 2N HCl at boiling for 3 hours. Chemical resistance was evaluated by the loss of fibre weight. The fibres were preliminarily subjected to thermal treatment in a muffle furnace in the temperature range from 300 to 800 C every 100 C, and the time of treatment was 10, 20, and 30 min at each temperature. The average diameter of the studied fibres was 10-14 µm. The fibres were produced under the same forming parameters on a single-filament laboratory stand. The raw material used was basalt with an acidity modulus of Mk = 4.7 and an initial fibre stability in 2N NaOH of 83.8 % and in 2N HCl of 78.7 %. It has been determined that the maximum increase in alkali resistance is observed at holding temperatures of 400 C and 800 C. The maximum increase in acid resistance is observed during heat treatment at higher temperatures of 600, 700, 800 C and is an increase of 20-25 % from the initial one. With an increase in treatment time, the values in both cases decrease, so the optimal isothermal treatment time does not exceed 10 minutes. In the process of heat treatment of fibres, structural changes occur due to phase transitions of iron oxides Fe2+ to Fe3+, with a change in colour, basalt fibres acquire a browner (reddish) shade of colour. The phase transition is accompanied by the appearance of crystalline phase, which causes an increase in fibre density by 10-20 % [1].

Keywords
modified basalt fibers; alkali resistance, acid resistance of basalt fibers

Acknowledgments
Not provided

References
[1] Diduk I.I., Chuvashov Yu.M., Yashchenko O.M., Gorbachov G.F., Klevtsov V.M., Study of the effect of iron oxides in the composition of rocks and technological parameters of obtaining melts and fiber characteristics Scientific notes [in Ukranian], Lutsk: LDTU, 2007. Issue 20, №2, P.47-50.