Building Materials and Products
DOI: http://www.dx.doi.org/10.24866/2227-6858/2020-3-14

Makarova N., Komarov А., Tsuprik V.

NATALIA MAKAROVА, Candidate of Engineering Sciences, Senior Researcher, Laboratory of Irreversible Deformation,
ORCID: http://orcid.org/0000-0002-2581-8066, ResercherID: Q-2525-2016, ScopusID: 35610298200, e-mail: maknat@bk.ru
Institute of Automation and Control Processes of Far Eastern Branch of RAS
Vladivostok, Russia
ALEXEY KOMAROV, Postgraduate, e-mail: komarov.ai@dvfu.ru
VLADIMIR TSUPRIK, Candidate of Engineering Sciences, ScopusID: 6507239252, e-mail: tsuprik.vg@dvfu.ru
Politechnical Institute
Far Eastern Federal University
Vladivostok, Russia

Strength and deformation properties of the contact
of composite reinforcement with fine-grained concrete

Abstract: At the time being, the use of composite reinforcement with inclusion of various types of fibers and polymers has increased in construction practice; extensive experimental studies are being conducted to assess its mechanical characteristics. However, the interaction between reinforcing bars and concrete is still poorly understood due to the diversity of materials and surface types. This paper presents the results of tests to study the bond behavior of FRP bars with fine-grained concrete. Five series of concrete cylinders with basalt-plastic embedded in them and fiberglass bars produced at industrial enterprises of the Primorsky Krai were tested for direct pulling. For comparison, two series of samples with steel bars of cold-drawn wire of classes B-I and Bp-I have also been tested. As the parameters studied, not only the strength properties of the adhesion boundary have been considered, but also the parameters of the stress-strain curves in the entire test range, including the descending branch. Deformations directly in the reinforcing bar have been recorded using an extensometer mounted on the reinforcing bar. Subsequent data analysis showed that the bong strength was mainly affected by the pitch of the ribs on the surface of the rods. It was found that the greatest bond strength was in the rods with a step of ribs of 15–20 mm. At the same time, in samples with such rods, initial high bond stiffness and almost no descending branches on the stress-strain curves were noted, which indicates brittle nature of bond failure. The use of similar reinforcement in the elements of building structures can lead to brittle fracture until their bearing capacity is exhausted, which is extremely undesirable. The bond strength of metal rods to concrete was lower than that of all tested rods of composite reinforcement bars. Thus, it was concluded that the quality of the FRP samples presented for the study and the prospects of using composite reinforcement as an alternative to steel bars in reinforced concrete elements are sufficiently high. At the same time, when developing new types of products, it is necessary to consider not only the strength of the reinforcement bar, but also its joint work with concrete in the structure throughout the entire operation, while ensuring the requirements of the Codes for ultimate adhesion stress.
Keywords: composite reinforcement, fiberglass reinforcement, basalt-plastic reinforcement, fine-grained concrete, bond between reinforcement and concrete.

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