Stainless Steel Rebars Research Articles

Mapping of Atmospheric Corrosion of Steel in Southeast India Using Inverse Distance Interpolation Technique

Reinforced concrete and steel structural elements undergo premature degradation and lose strength primarily due to corrosion. Corrosion is an electrochemical phenomenon and its severity depends on several environmental factors. Experimental data on the corrosion of steel is important for making engineering decisions toward improving the service life of civil infrastructures. No recent dataset on atmospheric steel corrosion in an Indian coastal environment is found to be available in the literature, and hence this research attempts to address some of the literature gap. This paper presents an experimental study conducted to determine the corrosion rate of TMT, high-chromium steel, and stainless steel rebars exposed in actual coastal and inland regions for a period of 1 y. The site locations were located in southeastern parts of Tamil Nadu state in India. Based on the first-year corrosion rate, the corrosion rate after extended exposure (10 y) was determined based on ISO 9224 recommendations. The atmospheric steel corrosion map of Tamil Nadu state was developed using inverse distance interpolation technique. Microstructural studies indicated the formation of lepidocrocite (γ-FeOOH) phase composition in the rust products collected from coastal regions.

Effect of high-energy shot peening on the corrosion behavior and chloride threshold concentration of AISI 316L stainless steel rebar in simulated concrete pore solution

The corrosion behavior and chloride threshold concentration of AISI 316L stainless steel reinforcement bar (rebar), subjected to high-energy shot peening (HESPed), are compared with its solution-annealed (SAed) counterpart in simulated concrete pore solution (CPS). X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed that HESP significantly reduces the surface grain size to the ultrafine/nanometric range and increases the density of various dislocation structures, including dislocation walls and cells. This augmented presence of grain boundaries and dislocations, acting as high diffusivity paths, contributed to the formation of a thicker surface film with higher Cr content and lower donor/acceptor density in the HESPed sample compared to the SAed. Moreover, corrosion behavior analyses in CPSs with NaCl concentrations ranging from 0.0 to 2.0 M demonstrated that HESPed samples exhibit broader passivation ranges, more positive corrosion potentials, and higher polarization resistance under equivalent chloride concentrations. Additionally, threshold chloride concentrations obtained from the potentiodynamic polarization tests show values between 0.5 and 1.0 M for the SAed and between 1.0 and 1.5 M for the HESPed samples. Based on diffusion equations, a physical model is proposed to elucidate the improved behavior resulting from the HESP treatment.

Environmental life cycle assessment (LCA) for design of climate-resilient bridges – a comprehensive review and a case study

The life cycle assessment (LCA) study of a bridge and bridge network would provide the environmental profile and hotspot information including the GHG emission of different life stages, among the components. Compared with a rapid adoption of Road LCA into the procurement process in the developed countries, Bridge LCA however remains a nascent area where a few studies conducted in North America. The critical issues of environmental profile, hotspots and benchmarks of bridges remain a challenge due to the complexity of bridge structures, data collection and unfamiliarity of LCA in the bridge community. To address the challenge, this study presents a comprehensive bibliometric analysis and review regarding life cycle environmental impacts assessment of bridge projects around the world to identify the research pattern in order to capture the areas of research needed inside this theme. As a proof of concept, this study continues with conducting an LCA case study of a Bridge Replacement Project on a Canadian signature highway, demonstrating the adoption of the LCA methodology and a framework to streamline the collection of data, to develop, present, and interpret the environmental impacts, in terms of the durability and service life of the bridge asset. The study found that stainless steel rebar decks outperformed black steel decks in terms of CO2 reduction by over 10%, with transport fleet impacts being a significant part of the bridge’s overall environmental impact, highlighting the need for diverse functional units in bridge life cycle assessment studies.

Seawater Corrosion Resistance of Duplex Stainless Steel and the Axial Compressive Stiffness of Its Reinforced Concrete Columns

In order to explore the corrosion resistance of duplex stainless steel under seawater corrosion and the compressive stiffness of its reinforced concrete columns, this study first performed seawater corrosion resistance tests on HRB400 ordinary steel rebar and S32205 duplex stainless steel rebar. The effect of the corrosion product film on the corrosion behavior was investigated through polarization curve tests and electrochemical impedance spectroscopy tests. The results showed that the corrosion rate of S32205 duplex stainless steel in a seawater environment was approximately 1/15 that of the HRB400 ordinary steel rebar. The anodic polarization curve of duplex stainless steel rebars exhibited a greater slope than that of carbon steel rebars. In the simulated seawater environment, the corrosion rate of these two kinds of steel bars showed different trends. The corrosion rate of ordinary steel bar HRB400 first decreased and then increased, while that of duplex stainless steel S2205 increased steadily. Furthermore, 18 short concrete columns reinforced with ordinary and duplex stainless steel rebars were subjected to the axial compression test and stiffness analysis; the stiffness of the short columns was calculated from the test data. The theoretical values agreed with the test values, with a stiffness calculation error of less than 5%.

Stainless steel reinforcement: New material in the latest draft of second‐generation Eurocode 2

AbstractThe durability of reinforced concrete structures exposed to aggressive environments is affected by corrosion of carbon steel reinforcement. For this reason, it is of great practical interest to look for alternative solutions guaranteeing durability through the incorporation of corrosion‐resistant materials, such as stainless steel rebars. This type of steel is specially recommended for structures with a long lifespan, located in aggressive environments, with chlorides or de‐icing salts, and for structures where repair, inspection and rehabilitation is complicated. This solution presents a challenge from the point of view of the materials themselves, the mechanical design and their durability. This article presents the material properties of stainless steel and their influence on concrete structures. Furthermore, it is explained how these properties have been taken into account in the latest draft of the second‐generation Eurocode 2.

Effects of cracks on chloride‐induced corrosion initiation and propagation of carbon and stainless steel rebar

AbstractCurrent durability design models for reinforced concrete structures in chloride‐contaminated environments do not consider the effects of cracks, which in practice are almost inevitable. Literature reports controversial results on corrosion propagation time of carbon steel (CS) in cracked concrete, while fewer information can be found on stainless steel (SS) rebar, which can be employed as additional protection strategy. In this experimental study, corrosion initiation and propagation of CS and SS rebar in uncracked and cracked concrete are presented. Prismatic specimens, reinforced with CS and 304L SS bars were subjected to a loading procedure to induce longitudinal micro‐cracks and exposed to a 3.5% NaCl solution for more than 2 years. Corrosion was monitored with electrochemical techniques and at the end of exposure corrosive attacks were observed. Results demonstrate the fundamental contribution of micro‐cracks in accelerating corrosion phenomena for CS, while SS is still in passive conditions also in cracked concrete.

Bipolar electrochemistry for high throughput screening of localised corrosion in stainless steel rebars

The corrosion performance of stainless steel rebars is assessed by using bipolar electrochemistry. This method produces a quasi-linear potential gradient across the sample, with the technique providing rapid access to test for the nucleation and growth of pits across a wide range of applied potentials. The localised corrosion behaviour and resulting growth kinetics of Types 304L and 316L austenitic stainless steels (ASSs) are compared to Type 2101 and 2205 duplex stainless steels (DSSs). The difference in selective phase dissolution between pitting and trans-passive corrosion in DSSs is compared, with critical pitting potential, pit nucleation numbers, growth kinetics, volume loss, and aspect ratio of these four stainless steels discussed.

Shear behavior of reinforced concrete beams repaired using a hybrid scheme with stainless steel rebars and CFRP sheets

Repairing corroded flexural-deficient reinforced concrete (RC) structures using a hybrid scheme with stainless steel (SS) rebars and carbon-fiber-reinforced polymer (CFRP) sheets revealed excellent structural performance and contributes to lower maintenance costs in the remaining service life of the repaired structure. However, although cutting the bottom arm of stirrups in a hybrid repair method could affect the structural performance of shear-critical RC beams since this effect was not investigated in the past research. In this paper, structural performance of a group of shear-deficient RC beams repaired using the hybrid method is investigated experimentally to examine the effect of cutting the bottom arm of stirrup on the shear capacity of the repaired beams. The test variables included the longitudinal reinforcement types (i.e. carbon and SS), shear reinforcement configurations, and CFRP sheet wrapping schemes. Experimental results demonstrate that cutting the bottom arm of stirrup for replacing the corroded tensile rebar could significantly reduce the shear capacity of the retrofitted beams. Therefore, strengthening using CFRP sheet is needed to restore the shear performance of the retrofitted beams. Test results revealed that complete wrapping of CFRP sheet is effective to overcome the shear deficiency due to cutting the bottom arm of stirrup in the shear-critical RC beams. In addition, the effectiveness of CFRP sheet wrapping schemes on shear performance of SS-RC beams is approximately identical with that of CS-RC beams. Finally, a design methodology to repair the corroded RC bridge using hybrid method is developed and presented based on bending and shear tests.

Bond strength and reliability analysis of stainless steel rebar embedded in fiber reinforced coral aggregate concrete

• The failure pattern of all specimens was that rebars were pull out from concrete. • The content of CFs for optimum bond strength is about 0.6%. • The modified thick-walled cylinder theory can accurately predict the bond strength. • The bond lengths were suggested based on the reliability analysis. In order to take full advantage of local material sources in marine environments, dead coral debris is used as a new type of aggregate to manufactured concrete. Due to that coral aggregate concrete (CAC) presents greater brittleness and the abundant existence of Cl - in CAC, carbon fibers (CFs) and stainless steel rebar (SSR) are adopted to reinforce CAC, so as to improve the mechanics of CAC and the durability of CAC structure. Therefore, it is essential to study the bond performance between CFs reinforced CAC and SSR. In this study, 63 CFs reinforced CAC specimens embedded with SSR were submitted for pull-out tests. All specimens showed a pull-out pattern, and further analysis showed that CAC strength, c / d ( c is the thickness of CAC cover, and d is the SSR diameter), and d / l a ( l a is the bond length) presented an approximately linear relationship with bond strength, while CFs content presented an approximate parabolic relationship with bond strength. Based on the above-mentioned results, a bond strength formula was obtained from regression statistics. Also, suggested bond lengths are given through reliability analysis based on the bond strength formula. Furthermore, corrections concerning the properties of CAC and SSR were made to the thick-walled cylinder model to derive the bond strength theoretically, with results showed that the theoretical value fits well with the experimental value.

Study on bond behaviour of stainless steel reinforced concrete

The stainless steel rebar (SSR) and concrete are mainly bonded to transfer force and coordinate deformation. Therefore, it is necessary to study the bond behavior of stainless steel reinforced concrete. In this paper, the reinforced concrete specimens of carbon steel rebar (CSR), austenitic stainless steel rebar(ASSR) and duplex stainless steel rebar (DSSR) are made by taking concrete strength, steel rebar diameter, anchorage length, thickness of concrete cover and stirrup ratio as test parameters. Through the pull-out test, the failure phenomenon, bond stress-slip curve, ultimate load and ultimate bond strength of three kinds of reinforced concrete specimens are compared. The influence regularity of different factors on the bond behavior of SSR concrete is studied.. The bond strength formulas of ASSR and DSSR concrete are obtained by data fitting. The test results show that: (1) Both CSR concrete specimens and ASSR concrete specimens are mainly damaged by steel pulling out; (2) The failure mode of DSSR concrete specimens is mainly concrete splitting failure; (3) The change of concrete strength has the greatest influence on bond slip of DSSR concrete, followed by CSR concrete, and finally ASSR concrete; (4) CSR concrete has the best bond slip performance, followed by DSSR concrete, and finally ASSR concrete; (5) The recommended design value and calculation formula of anchorage length of ASSR and DSSR are given.

Pitting initiation on 304 stainless steel in a chloride-contaminated pore solution under alternating temperature conditions

Abstract Pitting initiation on 304 stainless steel grades was investigated in alternating temperature pore solutions to simulate pitting on stainless steel rebar in a tropical marine environment. The results suggested that a larger amplitude of alternating temperature heavily doped the passive film, reduced the film’s thickness and increased the (Fe3+ox + Fe3+hy)/Fe2+ox and Cr3+hy/Cr3+ox ratios in the film. Alternating temperatures more significantly degraded the passive film and intensified the pitting sensitivity on the stainless steel when compared with the average temperatures of the alternating temperature cycles. More pitting initiation sites were observed on the samples that experienced the 22–60 °C and 22–70 °C alternating temperature cycles than their counterparts in 50 °C and 60 °C solutions, respectively.

Effect of cracks on the service life of RC structures exposed to chlorides

To move towards a more sustainable concrete, the enhancement of its durability is strongly encouraged and, dealing in particular with reinforced concrete (RC), this mainly means to prevent the damage due to environmental actions, e.g. due to chloride-induced corrosion. Therefore, there is the need of models aimed at designing durable structures. Usually the service life design models consider concrete in uncracked condition. In real structures, however, several phenomena can generate cracks on concrete surface, leading to an acceleration of the corrosion of steel rebar. A number of studies have been recently carried out in order to evaluate the influence of cracks on reinforced concrete durability in chloride-contaminated environment, however the knowledge of the effect of cracks on the initiation and propagation periods is still lacking. Furthermore, few studies have considered additional protection strategies, such as the use of stainless steel rebar. In this work, experimental results are presented concerning the influence of cracks on the service life of reinforced concrete structures in order to evaluate if cracks lead to an earlier corrosion initiation induced by chlorides. Prismatic specimens, reinforced with carbon steel and 304L stainless steel bars, were longitudinally cracked and exposed to ponding with 3.5% NaCl solution. The monitoring of corrosion behaviour showed that when cracks reached the steel surface corrosion initiated immediately.

Cyclic Polarization of Corrugated Austenitic Stainless Steel Rebars in Acid Rain: Effect of Fly Ash, pH and Steel Type

The present work studies the effect of fly ash content (0–25 wt.%), pH (8, 12.5), and steel type (316L, 304L) on the cyclic polarization of stainless steel rebars in electrolytes, simulating fresh concrete exposed to acid rain and corroded concrete cover that has exposed the reinforcement to direct acid rain attack. At the same time, it tries to elucidate the corrosion inhibition activities of a Greek lignite fly ash that is a high-Ca fly ash with a questionable effect on the corrosion resistance of concrete. A higher pH results in lower corrosion rates for both steels and all fly ash content. However, different passivity trends are noted for the two steels as a function of pH. The partial replacement of Ca(OH)2 with fly ash up to 20 wt.% has a beneficial effect on the electrochemical behavior of the stainless steel rebars, in terms of both uniform and localized corrosion resistance. However, this trend is reversed at 25 wt.% FA. The reasons for such trends are explored via microstructural examinations of the steels after polarization and XRD analysis of fly ash, as well as reinforced concrete containing fly ash.

Shear Behavior of Reinforced Concrete Beams Repaired Using a Hybrid Scheme with Stainless Steel Rebars and Cfrp Sheets

Shear Behavior of Reinforced Concrete Beams Repaired Using a Hybrid Scheme with Stainless Steel Rebars and Cfrp Sheets

Seismic performance of ductile corrosion-free reinforced concrete frames

<abstract> <p>Corrosion of steel bars is the main cause of the deterioration of reinforced concrete (RC) structures. To avoid this problem, steel rebars can be replaced with glass-fiber-reinforced-polymer (GFRP). However, the brittle behaviour of GFRP RC elements has limited their use in many applications. The use of shape memory alloy (SMA) and/or stainless steel (SS) rebars can solve this problem, because of their ductile behaviour and corrosion resistance. However, their high price is a major obstacle. To address issues of ductility, corrosion, and cost, this paper examines the hybrid use of GFRP, SS, and SMA in RC frames. The use of SMA provides an additional advantage as it reduces seismic residual deformations. Three frames were designed. A steel RC frame, SS-GFRP RC frame, and SMA-SS-GFRP RC frame. The design criteria for the two GFRP RC frames followed previous research by the authors, which aimed at having approximately equal lateral resistance, stiffness, and ductility for GFRP and steel RC frames. The three frames were then analyzed using twenty seismic records. Their seismic performance confirmed the success of the adopted design methodology in achieving corrosion-free frames that provide adequate seismic performance.</p> </abstract>

Experimental and numerical investigation of the cyclic response of stainless steel reinforced concrete columns

Corrosion of carbon steel reinforcement is the major cause of premature deterioration of reinforced concrete infrastructures. There is increasing interest in the use of maintenance-free materials such as stainless steel reinforcement in concrete, with inherent durability and resistance to various forms of corrosion and favourable mechanical properties, in particular high ductility and substantial strain hardening. This paper presents the results of the first large-scale testing programme on reinforced concrete columns with duplex EN 1.4462 stainless steel rebars. Three cantilever column specimens were tested, two with EN 1.4462 stainless steel reinforcing bars, subjected to constant compressive axial load plus (i) monotonic loading and (ii) lateral cyclic loading, and one B500 carbon steel reinforced control specimen. In addition, conventional pull-out tests and tensile tests were conducted for a comparative assessment of the bond-slip behaviour and mechanical properties of the reinforcing bars. Numerical modelling simulations were carried out with the open-source finite element analysis platform OpenSees to predict the nonlinear response of stainless steel reinforced concrete columns and the results were compared with the measured experimental performance data. The force–displacement global responses and the dissipated energy evolutions of the tested columns from the experimental and numerical models are presented and compared.

Durability study of stainless steel rebars in sea water mixing concrete

In order to study the durability of the stainless steel bars (SSRs) in the marine environment, 52.5 Ordinary Portland cement (OPC) and CA50 concrete specimens (CAC), ordinary carbon reinforcing steel bars, and S32304 duplex SSRs were used to make two concrete blocks. Electrochemical monitoring of steel bars in concrete was carried out in two marine environments, i.e. splash zone and full immersion zone, were simulated via alternating dryingwetting cycles and immersion in the simulated sea water solution. Test results show that the durability of concrete structure can be improved by using S32304 duplex SSRs and CA50 concrete specimens.

Structural behavior of concrete girders prestressed and reinforced with stainless steel materials

Stainless steel reinforcing rebars and prestressing strands are viable alternatives to carbon steel materials for prestressed concrete structures in extremely aggressive environments. They offer better durability and require less maintenance. This study experimentally investigated the transfer length and prestress losses of 15.2-mm- (0.6-in.-) diameter Duplex High-Strength Stainless Steel (HSSS) strands as well as the shear and flexural behavior of two full-scale 12.8-m- (42-ft-) long AASHTO Type II concrete girders prestressed with HSSS strands and reinforced with duplex stainless steel rebars. The girders were made composite by adding a deck slab. One girder was tested in shear at both ends while the other girder was tested in flexure. Experimental shear and flexural behavior of the girders exhibited a constant increase in load carrying capacity up to failure. The failure mode for the shear tests was web shear, and for the flexural test was rupture of the HSSS strands. Both girders tested in shear and flexure failed in a progressive manner as they exhibited adequate warning through noticeable deflection, excessive cracking, and large reserve strength from first cracking to failure. The applicability of AASHTO LRFD provision for stainless steel reinforcing materials was investigated. AASHTO LRFD equations for flexural resistance were modified to cover rupture of strand failure mode. Experimental shear strength and flexural strength of the girders were greater than the predicted values by AASHTO shear equations and modified AASHTO flexural equations, respectively.

Analysis of the main geometrical characteristics that affect the bonding of ribs in rebars thinly covered to repair masonry structures

The use of stainless steel rebars in the repair of masonry structures is widespread and has traditionally produced excellent results. In these cases, rebars usually present diameters of below 8 mm covered with thin layers of mortar or grout. Research is necessary to characterise bonding under these particular conditions, hitherto unavailable.In this research, the geometry of ribs is parameterised and later analysed through the Finite Element Method. To this end, the Microplane model and Cohesive zone model are employed. Based on the numerical results, the geometrical aspects of the ribs that mostly affect bonding are identified and discussed.

Flexural response of stainless steel reinforced concrete beam

Stainless steel (SS) is gaining popularity as a reinforcement of structural elements in many countries, primarily due to its enhanced corrosion resistance, improved performance against fire, and resilient behavior. This paper investigates the flexural response of concrete beams reinforced with plain stainless steel rebars. Considering variations in two concrete strength and three reinforcement ratios, this experimental program included a total of eight SS and four conventional mild steel (MS) reinforced concrete beams under four points bending test. The experimental results of SS reinforced beams of each category are presented in terms of force–displacement relation, failure pattern, beam deformation, and force-strain response. The experimental results suggest that the moment capacity of concrete beams can be improved by applying SS rebars when a low reinforcement ratio is used. Apart from common flexural and shear failure, rebar debonding failure at the beam ends was observed in SS reinforced beams. The ratios of experimental cracking moment capacity to the code recommended value are found in a range of 1 ± 0.3 for SS reinforced beams. The ultimate moment capacity of SS reinforced beams is observed 12–36% smaller than the code recommended capacity. The overall outcome of this study allows the engineers to think and apply SS as an alternative to MS as reinforcement of concrete beams.