Elaboration of a technology of class A500 reinforcing bar production with a complex of additional properties as per GOST 34028–2016 at JSC EVRAZ ZSMK

Abstract

On 01.01.2019 the interstate standard GOST 34028–2016 “Reinforcing bars for concrete structures. Technical specifications” will come into force, which will replace the standards GOST R 52544 (in the part of A500S class), GOST 10884 and GOST 5781. The new standard will introduce a complex of additional properties for reinforcing bars of A500 class to provide reliability of its application in the high rise construction, in areas of increased seismic activity, in aggressive media (sea areas) and in bridges construction (increased cyclic loads). In view of this a complex of work accomplished at JSC EVRAZ ZSMK to elaborate technologies of production A500 reinforcing bars, completely meeting the requirements of GOST 34028 regarding base characteristics (tensile strength, yield strength, elongation, technological ductility) as well as additional ones (corrosion resistance, endurance, high ductility). In addition, an evaluation of fire resistance and fire safety of the A500 class rebar (the characteristics not present in the standard) accomplished. To determine the additional characteristics the following tests done: for tensile and bending for rebar of high ductility (class A500E), for corrosion resistance (class A500K), for endurance (class A500У), for fire resistance and fire safety (class А500С and А500Е). As a result of the work accomplished it was determined, that reinforcing bars of trial production of 18Г2С steel, micro-alloyed by vanadium, meet the requirements of GOST 34028–2016 to A500E class. Also determined that the reinforcing bars of trial production of class А500К and А500Е, made of steel grades Ст3Гпс, Ст3Гсп and 18Г2С meet the requirements of GOST 34028 regarding corrosion resistance for their application in structures without preliminary strain. Besides it was shown, that the reinforcing bars of regular production made of Ст3пс and Ст3Гсп steel grades meet the requirements of GOST 34028–2016 to class A500У regarding to resistance against fatigue multiple repeating cyclic loads. The experiment data regarding the fire resistance and fire safety obtained for trial and regular production enabled to determine the heating temperature effect on the rebar mechanical properties depending on the steel chemical composition and the bar diameter.