PSI - Issue 30

A.A. Kychkin et al. / Procedia Structural Integrity 30 (2020) 64–70

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A.A.Kychkin et al / Structural Integrity Procedia 00 (2019) 000 – 000

1. Introduction Fiber reinforced plastics are widely used in various industries as a competitive alternative to traditional materials such as steel as they address the issue of infrastructure aging and failure due to corrosion in Jiang (2012), Wu (2007), and Stepanova et al. (2013).

Nomenclature F

force, N

period, month

t

strength limit, MPa elastic modulus modulus of loss

σ

E’

E’ ’ tgδ

mechanical loss tangent BFRP basalt fiber reinforced polymer CFRP carbon fiber reinforced polymer FPR fiber reinforced plastics GFRP glass fiber reinforced polymer

FRP rebars are usually based on glass, aramid, and carbon fibers. Davalos et al. (2011) suggest that GFRP rebars are more widely used due to their lower cost, whereas in Wu et al. (2015), the use of CFRP rebars is limited by the higher cost. Lately, BFRP rebars have aroused considerable interest, with more attention being given to a possible replacement for GFRP rebars as in Sahin (2018) and Kychkin (2015). BFRP rebars are considerably cheaper than CFRP, they are soundproof, demonstrate better resistance to thermal cycles than CFRP and GFRP rebars, they also exhibit comparable fatigue behavior as shown by Cao (2008), Lu (2016), Shi (2014), and Wu (2010). Lebedev et al. (2020) compared changes in physical-mechanical factors of GFRP and BFRP in aggressive environments. The analysis shows that basalt fiber is a good alternative to glass fiber for production of composite materials for various applications. Fedorov et al. (2016) estimated changes in properties of rebars made of an epoxy matrix reinforced with glass and basalt fiber exposed to cold climatic conditions during 3 years, without exposure to direct sunlight. The strength and elastic modulus in longitudinal bending of rebars were found to remain constant at 20°С and - 60°С. Dong (2018) found that BFRP and steel BFRP composite rebars show a decrease in the shear and bending strength. After conditioning, the residual rupture strength of rebars was found to be 45.2 % of the tensile strength. Startsev et al. (2018) compared effects of moderate warm marine and cold climates on properties of basalt reinforced plastic rebars during 30 months. It was suggested that the values of mechanical properties decrease in warm climates and increase in cold climate. Therewith the linear thermal expansion was shown to shift and increase. In this respect, we continue experiments to estimate BFRP climatic resistance exposed to extremely cold (Yakutsk) and moderate warm marine (Gelendzhik) climates. The purpose of the study is to determine the effects of environmental aging in BFRP rebars in the later stages of exposure applying sensitive physical methods. 2. Materials and methods The selected samples for research were unidirectional basalt fiber reinforced plastic 6 and 8 mm diameter rebars of an epoxy resin matrix produced in one product line at the same time interval based on State Standard 31938-2012 “Composite polymer reinforcement for concrete structures”. The test results after fabrication were taken as the reference values. To evaluate effects of climatic factors on property changes, the BFRP rebars were studied after 30 and 50 month exposure to extremely cold (Yakutsk) and moderate warm marine (Gelendzhik) climates in open testbeds.