Probability Of Corrosion Research Articles

Updating deterioration models of reinforced concrete structures in carbonation environment using in-situ inspection data

Physical models for carbonation-induced reinforcement corrosion and concrete cracking have been proposed mainly based on accelerated carbonation tests. However, it has been criticised for not being representable of the natural corrosion process, and may not be applicable to real structures, so it is meaningful to calibrate and modify these models with in-situ inspection data of reinforced concrete (RC) structures in actual carbonation environment. The available in-situ data with the current inspection technologies (non-destructive) include concrete cover thickness, concrete strength, carbonation depth, reinforcement corrosion proportion, cracking proportion, etc. Based on Bayesian updating theorem, the paper proposes an integrated procedure for the updating of carbonation-induced deterioration models with inspection data, and then the durability assessment of existing RC structures in remaining service lives. In the procedure, the carbonation depth model and the probability of reinforcement corrosion are firstly updated with the inspected data, and then the un-carbonated depth model, the cracking probability and the critical corrosion depth model for cracking are updated subsequently. The methodology is illustrated using a case study of a RC industrial building with an age of 33 years. The influences of prior distribution and inspection data amount on the updating effect are discussed. Especially, the uncertainty associated with the number of corroded samples due to the error in corrosion inspection is discussed, and its effect on updated corrosion probability is investigated.

“Eco-Efficient” Concrete incorporating Ceramic Waste powder and Red brick dust as an effective replacement for Ordinary Portland Cement and Fine aggregate

Concrete is one of the most frequently used building material. Its usage worldwide is twice that of steel, wood, plastics and aluminum. Concrete is the mixture of cement, fine aggregate, coarse aggregate and water. The cement releases carbon-di-oxide which contributes 8% of annually released carbon content around the globe. The cement and fine aggregate in concrete can be partially or fully replaced by other cementitious materials. Ceramic waste powder is dumped away which brings about lot of ecological contamination and threatening both farming and general wellbeing. The cement is replaced with ceramic waste powder and red brick dust in replacement for fine aggregate in 5%, 10% and 15% by its weight. The mechanical and durability test were studied for the design mix of M20 grade concrete. The mechanical tests include compressive strength, split tensile strength and flexural strength for which the optimum percentage of replacement of ceramic waste powder and red brick dust is found. In a similar way, durability test includes acid test and corrosion test were taken for 5%, 10% and 15% replacements. The mechanical and durability test results were compared with conventional (without replacement) concrete. These tests were completed to access the mechanical properties for 7 days, 14 days and 28 days. Results showed that, mechanical properties of concrete increases for 10% effective replacement of ceramic waste powder and red brick dust. Corrosion study shows that less probability of corrosion for 10% effective replacement. Negligible loss of weight is experimented form the acid study. Thus in clear, the test results shows that, effective replacement of ceramic waste powder and red brick dust by 10% replacement to cement and 10% to fine aggregate shows contemporary results with various extends in concrete.

Inspection and Assessment of Corrosion in Pretensioned Concrete Bridge Girders Exposed to Coastal Climate

The most common methods for detecting chloride-induced corrosion in concrete bridges are half-cell potential (HCP) mapping, electrical resistivity (ER) measurements, and chloride concentration testing, combined with visual inspection and cover measurements. However, studies on corrosion detection in pretensioned structures are rare. To investigate the applicability and accuracy of the above methods for corrosion detection in pretensioned bridge girders, we measured pretensioned I-shaped girders exposed to the Norwegian coastal climate for 33 years. We found that, even combined, the above methods can only reliably identify general areas with various probabilities of corrosion. Despite severe concrete cracking and high chloride content, only small corrosion spots were found in strands. Because HCP cannot distinguish corrosion probability in the closely spaced strands from other electrically connected bars, the actual condition of individual strands can be found only when concrete cover is locally removed. Wet concrete with high chloride content and accordingly low HCP and low ER was found only in or near the girder support zones, which can therefore be considered the areas most susceptible to chloride-induced corrosion. We conclude by proposing a procedure for the inspection and assessment of pretensioned girders in a marine environment.

Corrosion vulnerability of reinforced concrete structures with different blended cement due to chloride ingress

Indifference towards adequate durability concerns hampers the sustainability of Reinforced Concrete (RC) structures in adverse weather conditions, like the marine regions, where premature structural damages due to chloride ion induced corrosion leads to reduced service life. In strength focused mix design of concrete, selection of materials and mix parameters are usually oriented towards target strength with little or no consideration of associated corrosion risks. Therefore, absence of adequate durability-focused design guidelines can further exacerbate this alarming issue. As a potential remedy, it is substantial to focus on material development, aligning with a performance-based design approach, to safeguard durability of RC structures in extreme conditions. Although previous studies by the authors have observed significant improvement in concrete microstructure and permeation characteristics due to various binder types, however, there are no significant studies to quantify the corrosion risks associated with different Supplementary Cementitious Materials (SCM) contents. In this regard, this study has incorporated a full probabilistic approach to evaluate the corrosion risks, in terms of corrosion probability, associated with different SCM types (fly-ash and slag) and replacement proportions (up to 40%). The corrosion probabilities of mixes with a moderate strength have been estimated for a wide range of cover values and series of desired service life in marine environment. An overall quantitative overview of the corrosion probabilities, portrayed in the study can be utilized to conduct further studies for developing tentative guidelines to optimize binder type and proportion to ensure maximum safety against the corrosion risks.

Corrosion resistance of alkali-activated binary reinforced concrete based on natural volcanic pozzolan exposed to chlorides

Alkali-activated concretes are being considered as an alternative environmentally friendly construction materials compared to the ordinary Portland cement. However, although these materials have reported mechanical properties comparable to those of OPC, the corrosion of reinforcing bars is a major durability issue that needs to be studied. This article studies the corrosion performance of an alkali-activated binary reinforced concrete (AABC) based on natural volcanic pozzolan (NP) and ground blast furnace slag (GBFS) exposed to chlorides ions. OPC concrete was used as reference material. To carry out the study, accelerated chloride ingress methods (impressed voltage, wet-dry cycles, and saltwater immersion (3.5% NaCl)) were used. Monitoring of the corrosive process was carried out using the techniques of half-cell potential, linear polarization resistance, polarization curves and curves of current intensity versus time. As complementary techniques, surface electrical resistivity and resistance to chloride ion penetration were evaluated. AABC showed higher resistance to chloride ion penetration compared to OPC concrete, a reduction of the charge passed up to 60% at 360 days of exposition. In general, the various accelerated chloride ingress techniques employed in the present research revealed that reinforcing steel embedded in AABCs have a higher resistance to corrosion compared to steel bars embedded in Portland cement (OPC)-based concrete. It should be noted that the B constant values obtained for AABC differ from the values commonly used in (OPC)-based concretes. In addition, the results indicate that the ranges of corrosion probability, such as half-cell potentials or corrosion currents, specified for OPC concretes should be checked for its application in alkali-activated concretes.

Electrochemical corrosion behavior of type 444 stainless steel in synthetic tap water at different temperatures

PurposeThe purpose of this paper is to investigate the electrochemical corrosion behavior of type 444 stainless steel (SS) in synthetic tap water from 25°C to 80°C, i.e. the operation environment of the electric water heater.Design/methodology/approachThe corrosion behavior was studied by using electrochemical measurements such as electrochemical impedance spectroscopy and polarization curve. The specimen surfaces were observed with scanning electron microscopy. The passive films were characterized with X-ray photoelectron spectroscopy.FindingsIn the typical tap water, 444 SS passivates spontaneously under different temperatures. The passive films formed at higher temperatures contain relatively less Cr-species and more Cl− ions, resulting in lower polarization resistances. The stable pitting corrosion takes place in the potential region of oxygen evolution as the temperature increases to about 55°C. The critical Cl− concentration of pitting corrosion reduces from about 160 mg L−1 to 60 mg L−1 with changing temperature from 25°C to 80°C.Practical implicationsThe pitting corrosion probability was assessed through the statistical analysis of tap water quality. The results are useful for the application of 444 SS as well as the design of electric water heater.Originality/valueThis paper shows the variation of polarization resistance, pitting potential, passive film composition and critical pitting chloride concentration with the temperature of tap water. It is of great significance for the development and application of SS in tap water environments.

Experimental Study on Improvement Mechanism of Silane Emulsion on Acid Rain Corrosion of Green Ecological Concrete

Concrete structure is vulnerable to acid rain corrosion, which affects the service life of the material, in the corrosive environment, and concrete structure will deteriorate because of the erosion of water/chloride ions. Therefore, waterproof treatment of concrete structure is needed to improve the durability of the structure. In this study, the green ecological concrete is taken as the research object. The concrete is mixed with a certain amount of silane emulsion to reduce the probability of corrosion of concrete due to moisture and chloride ions, thereby prolonging the service life of this kind of concrete. During the experiment, in order to further test the corrosion resistance of silane emulsion to this kind of concrete, different kinds of concrete were taken as test objects and divided into 3 test groups, namely, the original test group (ITE), the non silane emulsion test group (TWSE) and the optimal ratio test group (OT-SE). It is proved by experiments that the best proportion of concrete mixed with silane emulsion is 0.32 of water binder ratio, 18% of coal powder mixing ratio, 37% of gravel mixing ratio and 0.23% of proportion of silane emulsion. The above factors are applied to compressive strength test, and 30 days as test time, the compressive strength of concrete with fly ash is measured. In the experiment of anticorrosion, compared with the traditional concrete samples, the electrical flux of concrete mixed with silane emulsion decreased by 28.7% in 8 h, that is, chloride ion permeability decreased significantly.

Effect of aggressive environment on durability of concrete containing fibrous rubber shreds and silica fume

AbstractThe present study deals with the investigation of durability properties of reinforced concrete fabricated by incorporating fiber type rubber shreds as fine aggregate in concrete and silica fume as a supplementary cementitious material. Concrete designs were produced to replace natural fine aggregate and cement by rubber shreds, and silica fume, respectively. The concrete mixes were studied for compressive strength up to 365 days, abrasion resistance, and water absorption up to 28 days. The carbonation and acid resistance (H2SO4 and HCl) properties were studied up to 90 and 180 days, respectively. Corrosion samples were tested up to 18 months for both macrocell current and half‐cell potential. The incorporation of rubber shreds lowered the compressive strength of concrete and resistance to water absorption, carbonation, and corrosion. However, the resistance to abrasion and acid attack was enhanced on the utilization of rubber shreds in concrete. The presence of silica fume considerably enhanced the mechanical and durability properties of rubber shreds concrete and lowered the probability of corrosion.

The Corrosion Probability and Flexural Strength of an RC Beam under Chloride Ingress Considering the Randomness of Temperature and Humidity.

The load capacity of reinforced concrete structure will decrease by chloride ingress in coastal region. In this paper, the corrosion probability and flexural strength of a typical reinforced concrete beam design under the influence of temperature and humidity was obtained by the Monte Carlo method. The relationship between flexural strength, temperature, relative humidity, and geometric parameters was established. The annual average temperature and relative humidity were treated as random variables together with the geometric size and concrete compressive strength. The corrosion probability and flexural strength in a wave splashing zone, coastal atmospheric zone, and offshore atmospheric zone were calculated. The results show that the corrosion probabilities of the three regions are obviously different. When the standard deviation of temperature is less than 1.5 °C, the temperature can be treated as a constant in the calculation of the concrete cracking probability in the wave splashing zone. A binary logistic regression formula was given to predict whether the randomness of temperature and humidity should be considered in the offshore atmospheric zone. When the standard deviation of the temperature is less than 1 °C, the temperature randomness has no significant effect on the flexural strength of beams in the wave splashing zone. The flexural strength distribution conforms to the normal distribution in the early stage of service and the Weibull distribution after concrete cracking.

Analytic studies of marine atmospheric corrosion based on multiphysics simulation

Because the environment at sea is more severe than inland, the corrosion of hull and ship equipment is extremely serious. It can be said that corrosion is one of the biggest factors affecting the life of ships. The cost of anti-corrosion for ships every year is one third or more of the total maintenance cost. The Marine atmosphere corrosion simulation of Q235 carbon steel is realized by Multiphysics simulation software. Due to the high probability and hazard of electrochemical corrosion in oceanic and atmospheric environment, this paper mainly analyzes electrochemical corrosion behavior and its influencing factors, providing a theoretical basis for monitoring and reducing corrosion hazards. The results show that the corrosion rate of Q235 steel in the oceanic atmosphere is 400 to 600 μm/a, and the corrosion rate is affected by temperature, humidity, limiting current density and other factors.

The Pitting Corrosion Probability of Copper in Solutions Containing Chloride and Sulfate Using Coupled Multielectrode Arrays

The preferred disposal method for used nuclear fuel is to seal it in containers emplaced in a deep geologic repository (DGR) in a suitable rock formation. In Canada, the container is a robust steel vessel coated with 3 mm of Cu as a corrosion barrier. Eventually, the DGR environment will become anoxic, and in the absence of oxygen copper is thermodynamically stable in water. However, since exposure conditions will initially be oxidizing due to the presence of trapped O2 upon sealing the DGR, there is a possibility of localized corrosion to occur. Mass balance calculations show that uniform corrosion during this period will be within the designed corrosion allowance, however, since the Cu coating is relatively thin and the required lifetime is long, the risk of pitting corrosion during this period must be carefully evaluated.Pitting corrosion susceptibility is determined by the corrosion potential of the material (Ecorr, the potential at which the rates of all anodic and cathodic reactions are equal), and the breakdown potential (Eb, the potential at which the copper oxidation rate on the surface increases abruptly due to the breakdown of the protective film), both of which are distributed parameters. This is due to the stochastic nature of passive film rupture and any uncontrollable variations in the structure and local environment at the metal surface. It is important to note that the analysis is based on the concept that pitting is only possible if the Ecorr is equal to, or more positive than the Eb.Our previous studies showed a passive behavior of copper surface when exposed to high pH solutions. In this work, a multielectrode array was used to obtain a statistically meaningful set of potential measurements through the simultaneous monitoring of 30 electrodes to determine their corrosion and breakdown potentials. From the extensive database that acquired, the Ecorr and Eb distributions were defined for the copper electrodes exposed to solutions containing various chloride concentrations and a more thorough evaluation of the relative values of Ecorr and Eb has undertaken to determine the susceptibility to pitting.Experiments were conducted using a multielectrode array in chloride and sulfate containing solutions at 25 °C and pH 8 and 11. In alkaline solutions, the copper oxide is more stable and can potentially form a passive film, whereas chloride and sulfate promote the breakdown of the passive film. As the concentration of aggressive anions increased, the values of Ecorr and Eb decreased, suggesting that the solubility of copper increases with in the presence of both chloride and sulfate. However, there is a critical sulfate concentration (~5 × 10-3 M) that above which the pitting probability of copper decreases.In general, the possibility of pitting increases with growing overlap between the distribution curves of Ecorr and Eb. To evaluate the possibility of pitting, histograms and distribution curves of Ecorr and Eb in the solutions that contain different chloride and sulfate concentrations were compared. In lower chloride concentrations, there was a very small overlap between distributions of Ecorr and Eb values; therefore, the possibility of pitting under these conditions is very low. On the other hand, a high chloride concentration at high pH indicated a higher probability of pitting, as the overlap between Ecorr and Eb distributions increased. Also, the extent of the passive zone decreased with increasing chloride concentration. In solutions containing sulfate content, the overlap between Ecorr and Eb increased with increasing sulfate concentration up to a certain content (~5 × 10-3 M), after this point the overlap decreased as the sulfate concentration increased. The results from potentiodynamic experiments indicated that increasing the chloride concentration resulted in decreased the extent of the passive zone; however, the sulfate did not seem to play a significant role in changing the extent of the passive zone.

The Effect of Vanadate, Phosphate, Fluoride Compounds on the Aqueous Corrosion of Magnesium Alloy AZ31 in Dilute Chloride Solutions.

The anodic polarization response of magnesium alloy AZ31 was first characterized during exposure to aerated 0.1 M NaCl solutions with millimolar additions of NaVO3, Na3PO4, Na2HPO4, NaF and various pairings to assess their ability to inhibit corrosion kinetics and retard localized corrosion. Each of the candidate inhibitors reduced the corrosion rate of the alloy to some degree. A Na3PO4–NaVO3 pair produced a good inhibiting effect decreasing the corrosion rate to about 10−7 A/cm2, which was two orders of magnitude lower than the uninhibited control case. A Bliss Independence assessment indicated that this inhibitor pair acted synergistically. A Na2HPO4–NaVO3 pair reduced the corrosion rate to 10−6 A/cm2 but was not assessed to be acting synergistically. The NaVO3–NaF pair did not reduce the corrosion rate significantly compared to the control case and was an antagonistic pairing. SEM imaging showed film formation due to exposure, which appears to be the origin of the observed inhibition. The resistance to localized corrosion was assessed as the difference in the breakdown potential and the corrosion potential, with larger values indicating a lower probability of localized corrosion during free corrosion exposures. The effects of the inhibitors on this characteristic were mixed, but each of the inhibitor pairs yielded potential differences in excess of 100 mV. A conceptual conversion coating process based on a mixture of vanadate and phosphate compounds were demonstrated. A fluoride-bearing formulation produced coatings whose total impedance was increased by a factor of two compared to an uncoated control. A fluoride-free formulation produced coatings whose corrosion resistance was increased by more than a factor of three.

Probabilistic modeling to predict fly-ash concrete corrosion initiation

This paper summarizes the results of a research aimed to show and analyze the results of a probabilistic model to predict the corrosion of steel embedded in fly ash concrete, through a multiphysical and multispecies model. This model developed to simulate the transport properties of ionic species was based on the finite element method applied to the Nersnt-Planck equation. It included ion to ion interactions, the chemical potential of species (concentration gradient), the electrical potential ionic interaction, the concentration of each species in the pore solution, the open porosity of the pore network, and the concrete chemical binding capacity (expressed as nonlinear binding isotherms). The model was implemented to determine the corrosion probability of concrete reinforced using three different fly ash replacement levels (0%, 20, 50%). It was based on the movement of ionic species through a saturated porous medium, by representing the microscopic interactions in a macroscopic way. The probabilistic method was based on a basic modified Monte-Carlo approach, which corresponded to a non-deterministic statistical numerical method for simulating random variables. The chloride diffusion coefficient, concrete porosity and chloride external concentrations were used as stochastic parameters. The results showed that the model was able to determine a probabilistic approach to corrosion onset time; In addition, they demonstrated the benefits and advantages of using of fly ash in the durability of concrete.

Corrosion of AISI 316 Stainless Steel Embedded in Sustainable Concrete made with Sugar Cane Bagasse Ash (SCBA) Exposed to Marine Environment

This research evaluates of the electrochemical behavior of steel bars of the AISI 316 and AISI 1018 embedded in sustainable concrete with partial replacement of CPC 30R by Sugar Cane Bagasse Ash (SCBA) and Silica Fume (SF). The electrochemical techniques used to evaluate the corrosion were half-cell potential or Ecorr -ASTM C-876-15- and the Linear Polarization Resistance Technique (LPR) - ASTM G59-. Ecorr and Icorr results indicate after more than 300 days of exposure to the marine environment (3.5% NaCl solution), a high resistance of AISI 316 steel, with Ecorr values lower than -200 mV indicating a 10% probability of corrosion, and a level of negligible corrosion, with values less than 0.1 µA/cm2 in the three mixtures, with sustainable concrete values slightly lower. The results indicate a resistance of more of almost 100 times greater than AISI 316 steel compared to the results obtained in AISI 1018 steel.

Corrosion of AISI 316 Stainless Steel Embedded in Sustainable Concrete made with Sugar Cane Bagasse Ash (SCBA) Exposed to Marine Environment

This research evaluates of the electrochemical behavior of steel bars of the AISI 316 and AISI 1018 embedded in sustainable concrete with partial replacement of CPC 30R by Sugar Cane Bagasse Ash (SCBA) and Silica Fume (SF). The electrochemical techniques used to evaluate the corrosion were half-cell potential or Ecorr -ASTM C-876-15- and the Linear Polarization Resistance Technique (LPR) - ASTM G59-. Ecorr and Icorr results indicate after more than 300 days of exposure to the marine environment (3.5% NaCl solution), a high resistance of AISI 316 steel, with Ecorr values lower than -200 mV indicating a 10% probability of corrosion, and a level of negligible corrosion, with values less than 0.1 µA/cm2 in the three mixtures, with sustainable concrete values slightly lower. The results indicate a resistance of more of almost 100 times greater than AISI 316 steel compared to the results obtained in AISI 1018 steel.

Temperature Impact on the Assessment of Reinforcement Corrosion Risk in Concrete by Galvanostatic Pulse Method

The electrochemical galvanostatic pulse method (GPM) is used for the evaluation of the degree of corrosion risk of reinforcement in concrete. This non-destructive method enables determining the corrosion promoting conditions through the measurements of reinforcement stationary potential and concrete cover resistivity, and determining the probability of reinforcement corrosion in the tested areas. This method also allows for the estimation of the reinforcement corrosion activity and the prediction of the development of the corrosion process on the basis of corrosion current density measurements. The ambient temperature (and the temperature of the examined element) can significantly affect the values of the measured parameters due to electrochemical character of the processes as well as specific measurement technique. Differences in the obtained results can lead to a wrong interpretation of reinforcement corrosion risk degree in concrete. The article attempts to assess the effect of temperature on the measured parameters while using the galvanostatic pulse method. The GP-5000 GalvaPulseTM set was used. The results of this study confirmed the impact of temperature changes on the values of three measured parameters (reinforcement stationary potential, concrete cover resistivity, and corrosion current density) and contributed to catching the trend of these changes.

Macrocell corrosion mechanisms of prestressing strands in various concretes

This paper investigates the mechanisms of corrosion of seven-wire strands and the reasons for failures in detecting corrosion at early stages. As per ASTM G109 and ACI 222 R-01, a 1-year study on chloride-induced corrosion of seven-wire prestressing strands embedded in various concretes was conducted. The type of corrosion current circuits in the prismatic specimens with one top and two bottom strands was investigated. Unlike solid rebars, the concrete resistivity had a limited role on the type of corrosion circuits in strand systems, with a high probability of corrosion occurring between different wires in the top strand itself. This may be due to the flower-like geometry and the complex corrosion mechanisms within the top strand. It is recommended to perform other electrochemical measurements on the top strand – prior to making conclusions. Also, until about 6% corrosion loss is reached, the rust will fill the interstitial space between the seven wires and will not exert expansive stresses on the surrounding concrete. Hence, no staining/cracking will be visible on the concrete surface – a serious structural safety issue – necessitating frequent chloride/corrosion condition assessment of prestressed-concrete structures.

Investigation of the failure mechanism of the TG-201 inhibitor: Promoting the synergistic effect of HP-13Cr stainless steel during the well completion

TG-201 inhibitor could minimize corrosion of HP-13Cr SS in the process of live acid. Moreover, it accelerated the probability of serious corrosion of SS during the well completion. The failure mechanism of TG-201 inhibitor was investigated using surface analysis and electrochemical measurements. TG201 inhibitor contains amounts of Cu2+, which would acquire the electrons prior to H+ to form Cu film. The failure mechanism was due to the synergistic effect attributed to the Cu film. Cu film promoted the formation of the occluded cell and the changes of fluid state evoked by the increase in interfacial roughness during the well completion.

Strength and Durability Performance of Ferrocement Panels with the Influence of Corrosion Inhibitor

Success of Ferrocement, as with other construction material, depends largely upon its durability. ACI-549R strongly recommends that studies be undertaken to suggest durable and long-term anti-corrosion techniques to prevent penetration of water and salts that could lead to the corrosion of reinforcing wire mesh. The main objective of this study is to develop a durable Ferrocement panel by incorporating corrosion inhibitors as admixtures. The inhibitor used is sodium nitrate based inhibitor. Totally 24 Ferrocement panels are subjected to strength and durability study to ascertain the influence of inhibitor modification in cement mortar. Inhibitor admixed mortar offers marginally improved resistance against water absorption irrespective of tested dosage levels as compared to control mortar. There is a appreciable reduction in current development in the order of 18% for inhibitor admixed mortar as compared to control mortar, which is an indication of improved resistance against chloride penetration. Half-cell potential readings on galvanized Ferrocement panels should not be interpreted for corrosion probability as per ASTM C876. Ferrocement panels with crimped wire mesh and inhibitor modification offered low corrosion risk at the end of test period as per ASTM C876. There is an improvement in ultimate load carrying capacity for galvanized mesh Ferrocement panels of the order of 11-16% upon inhibitor modification in mortar. Similar ultimate load carrying capacity for crimped wire mesh Ferrocement panels for control and inhibitor modified mortar. Ductile behavior associated with multiple crack formation before failure is observed for all tested panels. It can be concluded that crimped wire mesh panel Ferrocement panels offered appreciable stiffness, load carrying capacity and ductility as compared to galvanized mesh Ferrocement panel. Inhibitor incorporation appreciably improves the durable performance of Ferrocement panels.

Effect of Silica Fume and Fly Ash Admixtures on the Corrosion Behavior of AISI 304 Embedded in Concrete Exposed in 3.5% NaCl Solution.

The use of supplementary cementitious materials such as fly ash, slag, and silica fume improve reinforced concrete corrosion performance, while decreasing cost and reducing environmental impact compared to ordinary Portland cement. In this study, the corrosion behavior of AISI 1018 carbon steel (CS) and AISI 304 stainless steel (SS) reinforcements was studied for 365 days. Three different concrete mixtures were tested: 100% CPC (composite Portland cement), 80% CPC and 20% silica fume (SF), and 80% CPC and 20% fly ash (FA). The concrete mixtures were designed according to the ACI 211.1 standard. The reinforced concrete specimens were immersed in a 3.5 wt.% NaCl test solution to simulate a marine environment. Corrosion monitoring was evaluated using the corrosion potential (Ecorr) according to ASTM C876 and the linear polarization resistance (LPR) according to ASTM G59. The results show that AISI 304 SS reinforcements yielded the best corrosion behavior, with Ecorr values mainly pertaining to the region of 10% probability of corrosion, and corrosion current density (icorr) values indicating passivity after 105 days of experimentation and low probability of corrosion for the remainder of the test period.