Corrosion performance of steel reinforcement in concrete admixed with magnesium chloride and sulphate

Abstract

Purpose Besides with a large amount of Na+ and Cl− ions in seawater, the presence of Mg+2 and SO4−2 ions builds more complex corrosion mechanism. This paper aims to investigate the corrosion of embedded reinforcement in concrete with the environment of both Cl− and SO4−2 anions associated Mg+2 cation. Design/methodology/approach The concrete specimens were prepared by using ordinary Portland cement (OPC), and OPC blended with metakaolin (MK) for water to cementitious material ratio (w/cm) 0.48 and 0.51. The concrete mixes were contaminated with the addition of MgCl2 alone and combined MgCl2 and MgSO4 in mix water. Reinforcement corrosion was evaluated by half-cell potential and corrosion current densities (Icorr) at regular intervals. Moreover, the influence of cementitious material type, salt type and w/cm ratio on electrical resistivity of concrete was also investigated. The statistical models were developed for electrical resistivity as a function of calcium to aluminium content ratio, compressive strength, w/cm ratio and age of concrete. Findings Although the corrosion initiation time increases in the concomitant presence of MgSO4 and MgCl2 as internal source compared to MgCl2, Icorr values are higher in both OPC and MK blended concrete. However, electrical resistivity decreased with addition of MgSO4. MK blended concrete performed better with increased resistivity, corrosion initiation time and decreased Icorr values. Originality/value This study reports statistical distributions for scattered Icorr of rebar in different concrete mixtures. Stepwise regression models were developed for resistivity by considering the interactions among different variables, which would help to estimate the resistivity through basic information.

Study on Flexural Performance of Architectural Concrete Beams Under Steel Bar Corrosion Conditions

“…The volume of these products is significantly larger than that of the original steel bar, which leads to gradual cracking on the surface of concrete. 2Fe(OH)3+nH2O=Fe2O3•nH2O+2H2O (7) 2Fe(OH)3→Fe2O3+3H2O (8) 6Fe(OH)2+O2→Fe3O4+6H2O (9) In this study, when simulating the conditions of rebar corrosion, the well-cured RC was first immersed in an etch tank filled with 5% sodium chloride solution for two days to moisturize the concrete protective layer, establishing an electric current path. When conducting corrosion, the preembedded wire was connected to the positive terminal of the direct current power supply, and the iron mesh was connected to the negative terminal.…”

“…They discovered that corrosion products tended to deposit within large pores located close to the steel bar, such as drainage areas and voids. Raghu et al [7] examined the corrosion of steel bar in RC structures under an environment where chloride ions and sulfate ions coexist with magnesium ions. They observed that RC structures mixed with ordinary Portland cement (OPC) and metakaolin (MK) exhibited improved resistance against corrosion.…”

Evaluation of Structural Integrity for High Rise Buildings Using Non-destructive Test Method

“…The reason is that the building is located near to seashore. The potential of carbonation and corrosion could occur [18][19][20]. A combination of external effects from sea which a potential to sulfate is promoted to the lowering the integrity of beam 3B as compared to the other beam 3A and 4A respectively.…”

Research on the application of information technology modeling based concrete reinforcement construction for bridge projects

“…Concrete reinforcement is crucial in bridge engineering construction, which can effectively avoid damage to the building structure affected by various factors and reduce the bridge building safety risks and safety hazards [1]. In the construction of bridge engineering, the durability and safety of the bridge-building structure should be considered comprehensively, and the concrete should be reinforced through certain technical means [2][3]. Usually, the structural strength and stiffness of the concrete structure under different loading conditions have certain differences [4].…”