Chloride-contaminated Concrete Research Articles

Differences between Using Mortars and Solutions When Testing Sodium Silicate as Corrosion Inhibitor for Construction Steel

Corrosion inhibitors are regularly used to minimize corrosion progress in reinforced concrete. Nitrite ions are very effective inorganic inhibitors but not environmentally friendly, since they can leach and contaminate the surrounding soil and water [1, 2]. Among other promising inorganic ions, silicate ions are of particular interest due to their low cost and low toxicity, although most results have been reported in pore simulating solutions. There is little information in the literature where silicate ions are evaluated as corrosion inhibitors in mortar or cement pastes. The purpose of this study is to show some contrasts between the effectiveness of silicate ions as carbon steel inhibitors when they are tested in solution or in mortar.The results in solution (ASCl) were obtained in an alkaline electrolyte (pH=13) that simulates good quality concrete contaminated with chloride ions [3,4]. ASCl contains KOH 0.08 mol/L, NaOH 0.02 mol/L, Ca(OH)2 0.001 mol/L and NaCl 0.3 mol/L, so that [Cl-]/[OH-]=3. The solution containing silicate ions (SSCl) incorporates Na2SiO3.5H2O 0.3 mol/L, corresponding to [inhibitor]/[Cl-]=1. The electrochemical evaluation included standard tests such as cyclic voltammograms, polarization curves, electrochemical impedance spectroscopy (EIS) and weight loss tests involving long exposure times. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used to investigate the composition of the surface films. The findings for bare rebars demonstrate that the presence of silicate ions in solution may effectively prevent carbon steel corrosion, with an inhibition efficiency greater than 99% and no localized attack seen after 30 days of immersion. It has also been observed that a 24-hour pretreatment at open circuit potential (OCP) in silicate solutions (SS) improves the corrosion resistance of construction steel when tested in SSCl. The polarization curves show higher pitting potential and lower corrosion current intensities when compared to untreated electrodes. XPS spectra show that silicate ions are incorporated into the surface film. Pretreatments in SS produce passive films that are rich in Fe(II), present mainly as oxohydroxides. EIS shows that the film is more resistive and compact. In contrast, the reference pretreatment in the absence of silicates led to surface films composed mainly of Fe(III) oxides and oxohydroxoxides.Tests in mortars were carried out including reinforcement bars (rebars) in mortar prepared with water/Portland cement=0.6 and sand/cement ratio =3. Mix R (for reference) had no admixed inhibitor and mix S incorporated Na2SiO3.5H2O using a 0.3 mol/L solution to replace the water in the mix. Also, samples P contained rebars pre-treated by previous immersion in silicate ions solutions, in mortars with the same composition as mix R. Once cured for 7 days, the mortar samples were immersed in aerated 0.3 mol/L NaCl solution for 3 months. The electrochemical follow-up included periodical evaluation by EIS and Rp. The alkaline reservoir in the mortar (which is the content of insoluble Ca(OH)2) was investigated by thermogravimetric analysis. Also, a lixiviation test was designed using pH indicators to verify changes in basicity after a lixiviation process. In mortars R and S, charge transfer and polarization resistance (Rt and Rp) remained lower than 50 kΩ cm2 after the first 15 days. However, Rt and Rp higher 100 kΩ cm2 were measured for rebars P after 15 and 60 days of exposure. The differences between P and R tend to flatten after 90 days of exposure. This shows that the inhibitor effect of pretreating the rebars (P) is lost over a longer period of time. According to the results from thermogravimetric tests, silicate ions in mortar consume Ca+2 ions, producing NaOH. Since this is more soluble than Ca(OH)2 it lixiviates quicker, causing the pH to decrease. Lixiviation tests support this theory.In summary, silicate ions are very effective corrosion inhibitors when tested in alkaline solutions. When silicates are used to pretreat the rebars the beneficial effect is lost after 90 days. When solutions containing silicate ions replace water in the mortars´ preparation, the inhibitory effect is lost faster due to the consumption of portlandite and the consequent acidification of the mortars.References Gaidis, J.M., Chemistry of corrosion inhibitors. Cement & Concrete Composites, 2004. 26(3): p. 181. Elsener B., Corrosion inhibitors for steel in concrete. State of the art report. London, ed. M. Publishing. 2001. Montes, F., et al., Silicate Ions as Corrosion Inhibitors for Carbon Steel in Chloride-Contaminated Concrete Pore Simulating Solutions. Corrosion, 2020. 76(12): p. 1147-1154.Rolandi A.C. et al. Corrosion Engineering, Science and Technology 57(5) (2022) 455–463. Figure 1

Effect of ECE in removing chlorides at free and bound ones in concrete contaminated with chlorides in cast and with penetrated chlorides

The present study concerned the effect of electrochemical chloride extraction (ECE) to chloride-contaminated concrete on chloride removal with incremental depths after the ECE at 1000 mA/m2 for 2, 4 and 8 weeks. The steel reinforcement was taken as an anode, while the titanium mesh as cathode. The chloride was extracted by diluting concrete dust sample in acid solution and still water for total and free chlorides, respectively. As a result, most free chlorides were removed from concrete at the increased current density, while bound chlorides were quite removed, presumably due to a reduction of the alkalinity of concrete.

A comparison study of constant current and square wave current in the bidirectional electromigration rehabilitation on chloride-contaminated concrete

The objective of this study is to reduce the hydrogen embrittlement risk of rebar caused by the continuous constant current (CC) in the bidirectional electromigration rehabilitation (BIEM). Three types of square wave current (SWC) were applied in the BIEM treatment on a Cl--contaminated concrete, in the saturated calcium hydroxide containing 1 mol/L triethylenetetramine (TETA). The sample experienced the BIEM with a constant current density of 3 A/m2 was chosen as the control sample with the same electricity consumption. After 4 cycles of treatment, the concentration profiles of Cl- and TETA were measured in the protective layer. The corrosion current densities of the rebar were analyzed by various electrochemical tests. The stress-strain curve of the rehabilitated rebar was tested, and its hydrogen embrittlement risk was estimated. The results suggested that the SWC more effectively removed Cl- and migrated TETA than the CC did, with the same electricity consumption and treatment duration. The rebar experienced the former BIEM exhibited a higher fracture energy ratio and a lower corrosion rate than the one experienced the latter treatment. In general, the SWC was more effective and lower hydrogen embrittlement risk than CC in the BIEM rehabilitation treatment.

Effects of Zinc alloy layer on corrosion and service life of galvanized reinforcing steels in chloride-contaminated concrete

Corrosion of reinforcing steel affects the service life of structures. A chloride environment exposed to reinforced concrete structures accelerates the corrosion process. Hot-dipped galvanized steel was used as reinforcing steel instead of bare carbon steel to provide better protection against corrosion. The coating layers of galvanized steel have different compositions which can affect corrosion behavior. When galvanized steel has been corroded, it will expose the zinc-alloy layer that has a different composition than the top pure zinc layer. A comparative study on electrochemical properties such as concrete resistivity, polarization resistance, corrosion current density, anodic Tafel slope, cathodic Tafel slope, and corrosion rate of bare carbon steel (BS), galvanized steel (GS), and corroded galvanized steel (CGS) was conducted. The BS, GS, and CGS were embedded in concrete with different mix proportions by varying water-to-binder ratios, chloride contents, and types of binder. The electrochemical properties data were measured by the Wenner four-probe, linear polarization resistance (LPR), and potentiodynamic polarization resistance (PPR) tests. The measurement results show that the resistivity of 0.4 w/b concrete is higher than 0.6 w/b concrete. Corroded galvanized steel's polarization resistance is lower than bare carbon steel's and galvanized steel's. The corrosion rate calculated from the Stern-Geary equation of corroded galvanized steel is higher than bare carbon steel and galvanized steel. Based on the calculation results, the specimens with galvanized steel have a longer crack-initiating life than the bare carbon steel. The crack-initiating life of the reinforced concrete structures using galvanized steel can be more precisely predicted by considering the corroded galvanized layer.

Effects of Mineral Admixtures on Macrocell Corrosion Behaviors of Steel Bars in Chloride-Contaminated Concrete

Based on the macrocell corrosion theory and by alternating the microcell corrosion state and macrocell corrosion state, the influence of mineral admixtures, such as fly ash, slag, and limestone powder, on the macrocell corrosion behaviors of steel bars embedded in chloride-contaminated concrete were investigated and clarified. The results indicated that the inhibition effect induced by slag on macrocell corrosion and microcell corrosion was obviously better than that induced by fly ash or limestone powder. The presence of slag in chloride-contaminated concrete could remarkably decrease the corrosion area ratios of anodic steel, even if the replacement levels of slag to cement reached 70%. With the addition of mineral admixtures into concrete, the ratio of macrocell current density to microcell current density was decreased to some extent, depending on the types, replacement levels, and replacement ways of mineral admixtures. The use of slag and fly ash in chloride-contaminated concrete can effectively weaken the macrocell corrosion and make the corrosion be dominated by microcell corrosion. The types and replacement levels of mineral admixtures also had a remarkable influence on the control mode of macrocell corrosion. The use of slag was more effective than that of fly ash or limestone to weaken the cathode control mode of macrocell corrosion and made the control mode of macrocell corrosion be dominated by jointed control.

Electrically driven ionic transport in the RCM and RIM: Investigations based on experiments and numerical simulations

In this work, the rapid chloride migration test (RCM) and the rapid iodide migration test (RIM) were utilized to investigate ionic transport in concrete with the aid of an externally applied electric field. Unlike most existing work, this study establishes computational models of ionic transport in chloride-contaminated and chloride-free concrete. The model is validated by the consistency between the numerical and experimental chloride profiles. It is found that the chloride migration depth in the RCM test is obviously affected, and the results for chloride-contaminated concrete are 50% larger compared with those for chloride-free concrete. However, the difference between the two kinds of concretes is only 5% when measured using the RIM test. Thus, the results of the RIM test are more accurate and provide a better choice for applications to characterization of chloride-contaminated concrete.

Influence of chloride cations on pore solution chloride and critical chloride threshold of carbon steel rebar

ABSTRACT As part of ongoing research to validate the efficacy of a potentiodynamic polarization technique of determining the critical chloride threshold (CCRIT) value of steel reinforcing bars exposed to chloride-contaminated concrete, the present work reports CCRIT values of carbon steel exposed to NaCl, CaCl2 and MgCl2. The increasing use of locally available multi-chloride anti-icing agents in Ontario during the winter season, which are brine solution with ~21% chloride as NaCl, CaCl2 and MgCl2, resulted in a need to understand the impact of these salts on the threshold values. The potentiodynamic polarization method allowed the influence of these salts on CCRIT values of carbon steel rebar to be determined in a significantly shorter period than existing standard methods. Cement pastes with varying admixed chloride as NaCl, CaCl2 and MgCl2 were cast with 0.5 w/cm ratio and their pore solution content was expressed after 28 days curing for cation and anion analyses. The resulting pore solution composition revealed increasing Ca, K and Na cations and increasing chloride and sulphate anions when the cement pastes were admixed with chloride as NaCl. However, sulphates decreased in the pore solution when the pastes were prepared with CaCl2 and MgCl2. The consequence of the latter findings was that the threshold values by mass of pore solution of the carbon steel rebar exposed to these chloride compounds were significantly lower than bars exposed to pore solution with NaCl. Nevertheless, the conversion of these values to percentage by mass of cementitious materials gave surprisingly similar values for all three chlorides

Crevice corrosion of steel rebar in chloride-contaminated concrete

In this paper, crevice corrosion was proposed as one of the important mechanisms responsible for the damage of steel rebar in concrete, which was experimentally verified in simulated concrete pore solution (SCPS) and concrete blocks. The effects of chloride concentration and temperature on the crevice corrosion were comparatively investigated by means of potentiodynamic polarization, immersion, electrochemical impedance spectroscopy (EIS) and galvanic current measurements. The crevice corrosion products in chloride-contaminated SCPS were examined by X-ray photoelectron spectroscopy (XPS). The results indicated that chloride contamination and temperature elevation could significantly accelerate the crevice corrosion.

Corrosion prediction models for steel bars in chloride-contaminated concrete: a review

Concern has been expressed in the recent decades about the corrosion prediction of concrete structures in a chloride environment. This paper summarises the corrosion prediction models developed for chloride-contaminated concrete, including both the empirical and electrochemical corrosion models. The definition methods of the steel de-passivation process for electrochemical models, such as anode–cathode ratio (Aa/Ac), critical chloride concentration (CCl,crit), modification of anodic Tafel slope (βa) or passive film resistance (Rf), are considered essential and discussed in detail. Furthermore, electrochemical parameters regarding the definition and selection in electrochemical models and experimental measurements are discussed. This study confirms that Aa/Acand CCl,crithave been generally used in recent years, and that the modifications of βaand Rfrelated to free chloride concentration are technically feasible. In addition, the discreteness of electrochemical parameters in electrochemical models and experimental measurements are observed, and time-dependent characteristics of electrochemical parameters are scarcely presented in the existing literature.

Corrosion performance of hot-dip galvanized zinc-aluminum coated steel rebars in comparison to the conventional pure zinc coated rebars in concrete environment

In this investigation zinc was alloyed with aluminum in order to improve the corrosion resistance of hot-dip galvanized coated steel rebars in contact with chloride-contaminated concrete. To rapidly assess the role of aluminum alloying in zinc, test panels in sheet form containing 10%, 15%, 20%, and 30% aluminum in zinc were prepared and evaluated in terms of their corrosion resistance via salt spray exposure tests. It was found that 10%Al-90%Zn (10AZ) provided the best results. Mild steel rebars were galvanized in 90%Zn-10%Al and 100%Zn (100Z) baths and their corrosion resistance performances when they were exposed to simulated concrete pore solution and embedded in mortars were examined. The10AZ-coated rebar showed superior corrosion resistance performance to the 100Z-coated rebar. Electrochemical impedance spectroscopy, DC polarization, scanning electron microscopy, Raman spectroscopy, and X-ray diffraction techniques were used to study the kinetics and corrosion mechanism of the coated rebars.

Silicate Ions as Corrosion Inhibitors for Carbon Steel in Chloride-Contaminated Concrete Pore Simulating Solutions

Silicate ions were tested as corrosion inhibitors for construction steel using concrete pore simulating solutions contaminated with chloride ions. The results were compared to those from solutions with no silicate and with no silicate and no chloride ions. The evaluation included typical electrochemical techniques such as cyclic voltammetry, polarization curves, and weight loss evaluation after a 60 day immersion. Surface analysis was undertaken using micro-Raman spectroscopy and x-ray photoelectron spectroscopy (XPS). Polarization curves showed no sign of pitting and low corrosion current densities if silicate ions were present, even when chloride ions were also in the system. In parallel, no localized attack was observed after 60 days of immersion in solutions containing an inhibitor/chloride = 1 ratio. Cyclic voltammograms and XPS spectra indicated that the presence of silicate ions affects the composition and thickness of the passive film: the film becomes thinner and contains more Fe(II) species. All of the results showed that silicate ions act as promising inhibiting agents.

Chloride migration measurement for chloride and sulfide contaminated concrete

Reinforcement corrosion is major reason for concrete structures deterioration. Chlorides from external sources such as seawater and de-icing salts penetrate in the concrete and as soon as a critical threshold reaches the reinforcement level corrosion processes start. Therefore, the characterization of the chloride ingress resistance in form of the rapid chloride migration (RCM) coefficient, DRCM is crucial to classify concretes for given applications and to enable full probabilistic service life prediction. To measure DRCM of chloride-contaminated concrete, a rapid iodide migration test was developed using iodide as penetration ion and an iodine–starch reaction for penetration depth indication. This indicator mixture has the disadvantage that it is not applicable on sulfide containing concretes such as ground granulated blast furnace slag concretes. In this paper, the reason for the unsuitability of this indicator is examined and alternative oxidation agents are found and validated to overcome this problem. The new indicator mixtures with hydrogen peroxide (H2O2) or/and potassium persulfate (K2S2O8) as oxidation agents are not only insensitive to sulfide contamination but are also applicable to common concrete compositions and could replace the existing indicator universally.

Monitoring the Corrosion of Steel in Concrete Exposed to a Marine Environment

Reinforced concrete structures require continuous monitoring and maintenance to prevent corrosion of the carbon steel reinforcement. In this work, concrete columns with carbon and stainless steel reinforcements were exposed to a real marine environment. In order to monitor the corrosion processes, two types of corrosion probes were embedded in these columns at different height levels. The results from the monitoring of the probes were compared to the actual corrosion damage in the different exposure zones. Electrical resistance (ER) probes and coupled multi-electrodes (CMEs) were shown to be promising methods for long-term corrosion monitoring in concrete. Correlations between the different exposure zones and the corrosion processes of the steel in the concrete were found. Macrocell corrosion properties and the distribution of the separated anodic/cathodic places on the steel in chloride-contaminated concrete were addressed as two of the key issues for understanding the corrosion mechanisms in such environments. The specific advantages and limitations of the tested measuring techniques for long-term corrosion monitoring were also indicated. The results of the measurements and the corrosion damage evaluation clearly confirmed that the tested stainless steels (AISI 304 and AISI 304L) in a chloride-contaminated environment behave significantly better than ordinary carbon steel, with corrosion rates from 110× to 9500× lower in the most severe (tidal) exposure conditions.

Anodic and Mechanical Behavior of Carbon Fiber Reinforced Polymer as a Dual-Functional Material in Chloride-Contaminated Concrete.

Carbon fiber reinforced polymer (CFRP) has been used as a dual-functional material in a hybrid intervention system (ICCP-SS) which integrates the impressed current cathodic protection (ICCP) and structural strengthening (SS). The mechanical behavior of CFRP as an anode has been investigated in some solution environments. However, the anodic and mechanical behavior of CFRP bonded to concrete is unclear. This paper focuses on the anodic and mechanical performance of CFRP bonded to the chloride-contaminated concrete by conducting an electrochemical (EC) test. The method of bonding the CFRP to the concrete and the shape of the steel embedded in the concrete were considered. The current densities of 20 mA/m2 and 100 mA/m2 were applied during 120-day and 310-day EC tests. The electrode potentials and driving voltages were recorded, and the bond interfaces of the CFRP were inspected after EC test. The residual tensile strength and failure modes of the CFRP were analyzed after tensile tests. Finally, the long-term performance of CFRP as a dual-functional material in ICCP-SS system was discussed. Results show that the externally bonding CFRP in ICCP-SS system can not only protect the steel in chloride-contaminated concrete effectively but also maintain 70% of the original tensile strength of CFRP at a charge density of 744 A·h/m2. The expected service period of CFRP as a dual-functional material bonded to the chloride-contaminated concrete was determined to be more than 42.5 years.

Service life extension of SH16 bridges – New Zealand's first hybrid corrosion protection

State Highway 16 (SH16) is a motorway of significant strategic importance, connecting central Auckland to the city's western suburbs and beyond. It carries an average of 90 000 vehicles per day and runs through an environmentally sensitive coastal marine reserve. Two bridges on the route – Whau River Bridge and Causeway Bridge – were rehabilitated due to extensive chloride contamination as a result of exposure to the marine environment. This paper offers a holistic review of the inspection, durability assessment and design processes, and discusses construction, operation and maintenance details. The durability assessment considered deterioration mathematical modelling with regard to service life extensions of 25 and 50 years. A hybrid corrosion protection (HCP) system was selected as the preferred corrosion management solution. The system operates in two phases, initially energised using low-voltage direct current power to arrest ongoing corrosion and thereafter in galvanic mode to provide corrosion prevention. A structural health monitoring system was also designed and installed to offer long-term performance monitoring. The HCP system minimised physical works on site, negated the requirement for extensive replacement of chloride-contaminated concrete, allowed work to take place around the natural tide cycles and offers long-term protection. This is the first HCP system designed and installed in New Zealand and is believed to be the first of its kind for prestressed concrete in tidal waters.

Comparison of atomic and molecular emission in laser-induced breakdown spectroscopy for the quantification of harmful species in cement-based materials

Due to the penetration of harmful chlorides into concrete, e.g. from de-icing salt, damage processes such as chloride-related pitting corrosion can occur if critical values are exceeded. In this study, multiphase materials such as chloride-contaminated concrete are examined in detail. A direct comparison is made by analyzing the spectroscopic information of simultaneously measured atomic and molecular emissions with laser-induced breakdown spectroscopy (LIBS). In addition, the influence on the calibration is examined on the basis of the combined spectral information of both reaction paths of the penetrated chlorides. The calibration models of univariate and multivariate methods were validated using reference samples with wet chemical analysis. The results are applied to a concrete sample of a parking deck, which was also analyzed by potentiometric wet chemistry. In order to account for the heterogeneity of concrete, spatially (200 μm) and spectroscopically (0.1 nm) resolved LIBS measurements were performed using a fully automated laboratory system. Simultaneous measurements with three spectrometers allow the analysis of the emission processes of several elements such as Cl, Ca, O, Si and Mg as well as the newly formed molecules CaO and CaCl. The evaluation of the molecular emission in combination with atomic lines extends the analytical performance, since different concrete phases such as aggregates and cement matrix can be better represented. The measurements were carried out in ambient air and with helium purge gas. The limit of detection (LOD) achieved for a combined evaluation of atomic and molecular emission was determined to be 0.028 wt%.

Corrosion Behavior of Stainless Steel in Chloride-Contaminated Carbonated Concrete

Abstract The use of chloride-contaminated raw materials can minimize the consumption of natural resources, e.g., fresh water and virgin rocks, in the production of concrete to increase the sustainability of the construction sector. However, the possible benefits in terms of improved sustainability of concrete can only be evaluated on the long term, considering the durability (i.e., concrete’s ability to guarantee an adequate service life when exposed in operating conditions). In this research, the use of stainless steel reinforcement in combination with chloride-contaminated concrete has been studied to construct durable and sustainable concrete infrastructures. Preliminary results showed that both austenitic (i.e., 304L and XM-28) and duplex (i.e., 23-04 and 22-05) stainless steels are suitable to be used in concrete made with chloride-contaminated raw materials and exposed to different environmental conditions, without chloride penetration. However, when stainless steel bars are embedded in carbonated concrete, their corrosion resistance might be impaired. This article compares the corrosion behavior of the different stainless steels, two austenitic (304L and XM-28) and two duplex (23-04 and 22-05), embedded in alkaline and carbonated concrete and exposed to different controlled environmental conditions to simulate aggressive environments. Results showed that 304L, 23-04, and 22-05 stainless steels are suitable to be used also in concrete contaminated by chlorides even after carbonation and in the harshest exposure conditions. Conversely, corrosion might initiate on XM-28 when exposed to the most aggressive exposure conditions.

Zn–Al–NO2 layered double hydroxide as a controlled-release corrosion inhibitor for steel reinforcements

Zn–Al–NO2 layered double hydroxide (LDH) is proposed as a controlled-release inhibitor for steel reinforcements in chloride-contaminated concrete. The cumulative amount of nitrite released from LDH is sensitive to the chloride concentration in the solution. Compared with NaNO2, Zn–Al–NO2 LDH increased the chloride threshold value from 0.15 to 0.25 M and simultaneously decreased the critical [NO2−]/[Cl−] molar ratio from 0.09 to 0.02. In conclusion, the Zn–Al–NO2 LDH exhibits considerably higher inhibiting performance due to the on-demand release of NO2–.

Chloride transport and microstructure of concrete with/without fly ash under atmospheric chloride condition

This paper presents a comprehensive investigation regarding the chloride transport and microstructure of plain concrete and fly ash blended concrete under atmospheric chloride environment. Experimental results demonstrate that all the free, bound, and total chlorides show a build-up of ion concentration in the chloride profile. A linear relationship between the total and free chloride content is observed. Both water-to-cement ratio and fly ash content have great impact on the chloride binding capacity and the chloride diffusion coefficient. Microscopic properties (e.g. morphology, pore size distribution, porosity) are evaluated for chloride-contaminated concrete, and their correlation with the chloride transport behavior is discussed.

Quantitative Study on MCI Rehabilitating Steel Bars in Chloride-Contaminated Concrete Based on Inhibition and Transport Behaviors

AbstractThe transport and inhibition behaviors of a migrating corrosion inhibitor (MCI, marked PCI-2015) in reinforced concrete (in this paper, only mortar specimens were used for testing) contained different contents of NaCl (0.25, 0.5, 0.75, and 1% by weight of cement) with three water-cement ratios (0.45, 0.55, and 0.65) were investigated by using absorption tests and electrochemical measurements. The results indicated that the measured absorption weight of PCI-2015 basically agrees with the numerical value calculated by the modified MCI transport model, and the representative absorbed weight of PCI-2015 in W/C 0.65 concrete with 1% NaCl was 16.23  g/kg at 1 day, while the corrosion current (Icorr) of steel bars in the concrete was reduced to 0.02  μA/cm2 from the initial data 1.38  μA/cm2. The visual observation of surface condition for steel bars in concrete mixed with 1% NaCl by broken specimens showed that the surfaces of steel bars in concrete treated with PCI-2015 were bright. X-ray photoelectron...