PSI - Issue 20

A.K. Kychkin et al. / Procedia Structural Integrity 20 (2019) 198–205 A.K.Kychkin et al / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction Progress in development of composite materials industry provides for designing, implementing and production of new materials in high- technology industries. Emergence of new materials implies necessity of research and applied studies on refining of technological solutions in the production of goods and constructions. Effectiveness of use of new materials depends on the solution of a number of scientific and technical problems, including the problem of assessment and prediction of operational firmness of polymer-composite materials (PKM) and products under simultaneous impacts of climatic and operational factors. The diversity of types and structures of PKM, as well as varieties of mechanisms of development of damages (defects) arising in materials at their exploitation as a component of a product under severe climatic conditions, lead to understanding that solution of the problem of improved physical, mechanical and operational properties of materials is impossible without obtaining a representative volume of reliable experimental information. Moreover, a natural experiment is recognized as the single reliable method to determine lifetime of materials or elements. Composite reinforcement made of the plastic reinforced with different types of continuous filaments, aramid and carbon fibers, fiber glasses, and basalt fibers, packed into a polymeric matrix is a modern and perspective product for re-placement of steel reinforcement. The main advantages of composite reinforcement as compared with metal one are: - higher strength rates (1.5-2 times higher, than those of steel reinforcement); - smaller weight (3.5-4 times lighter than that of steel reinforcement); - high elastic modulus with the small coefficient of relative elongation, high resistance to stress; - good rheological characteristics; - resistance to corrosion, minor changes of mechanical properties under impacts of acids, salts and alkalis; - electromagnetic properties – dielectric, radio transparent, magneto-inert (changes of strength properties under impacts of electromagnetic fields are excluded); - resistance to impacts of cold temperatures (doesn't lose its strength properties); - 100% adhesion with concrete, the linear expansion coefficient, equal with that of concrete, excluding rushes of reinforcement and cracking in an armor coat of concrete under impacts of temperature cycles. World -wide experience in use of composite reinforcement as effective substitute makes more than 30 years. Regulations on application and calculation of fiberglass reinforcement in construction are used in a number of countries according to ACI (2006), ACI (2004), CSA (2002), CSA (2006), JSCE, CNR-DT 203 (2006), GOST 31938 (2012), GOST 32492 (2015), СП 295.1325800.2017 (2017) . Composite basalt plastic reinforcement (BPA) is a new, innovative structural material with the similar unique properties as compared with traditional materials. The advantages of polymer materials reinforced with basalt fibers, according to their mechanical properties, cost, resistance to severe environs, and biological resistance are discussed by Dhand V. (2015),. R. Parnas (2007), Alaimo G. (2016), Wu G. (2015), Liu Q. (2006), Li H. (2012), Xie Y. (2016), Ammar M. A. (2014), Najafi M. (2016), Khalili S.M.R. (2017), El Refai A. (2014). By Parnas R. (2007), it has been shown that basalt plastics are resistant against impacts of water and reactive solutions. After 250 days of exposure to these environs at room temperatures, the ultimate tensile strength and elastic modulus change by 10 – 20%. According to data by Wu G. (2015), plates and pressed layers of impregnated basalt fiber are resistant to impacts of arid and humid climates, however, their mechanical properties are unstable, ranging within 30 – 40%. In work by Liu Q. (2006), durability and destruction of basalt plastics are compared to similar properties of fiber-glasses and coal plastics after exposure to damp environment and reactive solutions. It has been shown that the systems reinforced by basalt fibers have high resistance to these aggressive effects. The similar comparison is performed by Li H. (2012), Xie Y. (2016) Ammar M.A. (2014), and it is shown that ultimate strengths and elastic moduli in tension, bending and shear are not inferior to those of fiberglass. By Najafi M. (2016), Khalili S.M.R. (2017), El Refai A. (2014), the resistance of basalt plastic to effects of low and high temperatures, and also of thermocycles has been investigated, and stability of these materials to the specified effects has been shown. In works by El Refai A. (2013), Pandian A. (2014), similar conclusions about high resistance of BPA to effects of severe environs have been arrived at after assessment of impacts of water, salt and alkaline solutions on mechanical properties of rods with 11-12 mm diameter at normal and increased temperatures. By Chikhradze N.M. (2012),