Long-term Corrosion Monitoring Research Articles

Interaction of aluminum alloys with MKPC and Portland-based cements on the metal-matrix interface

Cementitious matrices are considered for the immobilisation of radioactive aluminium. The processes occurring at the interface between both materials are relevant for the long-term stability of the repository. The present study compares Ordinary Portland cement (OPC), CEM I-type, with alternative Portland blended cement (CEM IV and CEM I + 50% silica fume) and magnesium potassium phosphate cement (MKPC). Al A1050 and Al AA5754, with 3.5% Mg, have been used as reactive metal alloys. Two exposure conditions were employed: (1) water immersion and (2) isolated in sealed plastic films. Long-term corrosion monitoring (Ecorr, icorr and Vcorr) was evaluated to understand the effect of Al reactivity in the matrix. The associated H2 release was quantified to understand the changes at the metal/matrix interface. Furthermore, pore ion concentrations and the pore microstructure were evaluated. The metal/matrix interface alterations were analysed at the end of the tests. The study revealed that after 300 days of water immersion, the CEM I + 50% of silica fume matrix had reduced the pore solution pH down to 10.5 compared to CEM I, which remained high alkaline (pH 12.9), and CEM IV with no significant decreases (pH 12.3). In contrast, MKPC showed the lowest pH (7–9.8). Low Al corrosion rates were found with MKPC, followed by CEM I + 50% SF according to their lower pH. A corrosion product layer of 90-50 μm thickness was observed at the Al/CEM I matrix interface constituted of aluminium and oxygen. Furthermore, enrichment in Al was detected in the matrix (around 1 mm depth), causing the formation of ettringite nodules. Voids were detected at the interface level associated with the high volume of H2 released. The MKPC matrix showed no alteration at the metal/matrix interface due to the lower reactivity of the matrix and lower H2 release. A homogeneous and dense region (30 μm) rich in phosphorous, potassium and magnesium was observed near the metal surface.

Excellent corrosion inhibition efficiency of Catharanthus roseus (Nayantara or Sadabahar) leaf aqueous extract on mild steel in chloride-contaminated solutions at different pH

The efficacy of Catharanthus roseus (Nayantara or Sadabahar) leaf extract as a green corrosion inhibitor for mild steel in chloride-contaminated environments has been investigated in the present work. This study has employed a straightforward, practical, and less expensive Maceration process to prepare leaf extract. The adaptability of the extract as a corrosion inhibitor has been evaluated through electrochemical polarization and impedance studies in chloride-contaminated environments with varying pH levels. In addition, long-term corrosion monitoring has been conducted to evaluate the sustainability of the inhibitor against chloride-induced corrosion at a neutral pH level. This novel study has revealed that the extract defends mild steel against chloride assaults better at pH 2 than it does in neutral or alkaline conditions. Moreover, electrochemical studies and subsequent characterizations have confirmed the film-forming nature of the inhibitor.

Long-term Corrosion Monitoring for Evaluating the Performance of Repair Measures

For a highway operator, such as ASFiNAG, bridges are very important assets. Despite all regular maintenance measures, these structures are strongly subjected to aging and degradation because of their exposure. Chloride contamination poses a significant challenge, gradually reducing the durability and service life of these structures, necessitating repair measures. This paper focuses on the comprehensive analysis of data collected through on-site monitoring and nearby weather stations.Bridge components that were exposed to high chloride levels were rehabilitated with different systems and monitored for more than a decade. In the paper, the rehabilitation methods, sensor principles, and initial corrosion data are presented. Seasonal corrosion trends revealed interdependencies and offered insights into repair effectiveness and durability.This study provides insights into cost-effective and prospective maintenance strategies based on key indicators such as humidity, electrical resistivity, and corrosion potential. It assesses the condition of structures rehabilitated by hydrophobic treatment and coating using long-term monitoring data from an overpass. This offers valuable insights into the effectiveness of repair measures.Continuous monitoring allows for ongoing evaluation of degradation and maintenance efficiency, guiding decisions on future maintenance intervals. This research serves as an assessment of maintenance effectiveness, ultimately contributing to cost savings, extended lifespan, and reduced lane closure time of critical road infrastructure.

Long-Term Corrosion Monitoring of Bacterially Healed Concrete Using Electrochemical and Ultrasonic Techniques

Long-Term Corrosion Monitoring of Bacterially Healed Concrete Using Electrochemical and Ultrasonic Techniques

Long-term corrosion monitoring of carbon steels and environmental correlation analysis via the random forest method

In this work, the atmospheric corrosion of carbon steels was monitored at six different sites (and hence, atmospheric conditions) using Fe/Cu-type atmospheric corrosion monitoring technology over a period of 12 months. After analyzing over 3 million data points, the sensor data were interpretable as the instantaneous corrosion rate, and the atmospheric “corrosivity” for each exposure environment showed highly dynamic changes from the C1 to CX level (according to the ISO 9223 standard). A random forest model was developed to predict the corrosion rate and investigate the impacts of ten “corrosive factors” in dynamic atmospheres. The results reveal rust layer, wind speed, rainfall rate, RH, and chloride concentration, played a significant role in the corrosion process.

Reinforcement corrosion and transport of water and chloride ions in shrinkage-compensating cement concretes

The transport properties obtained from the accelerated tests on the concrete mixtures that contain shrinkage-compensating cement have indicated that addressing the issue of shrinkage may come with the expense of increased permeability. This raised a fundamental question concerning the long-term durability of reinforced concrete structures made with this type of cement. In the absence of similar studies, a comprehensive experimental testing program was devised in the current study to understand the vulnerability of steel bars embedded in shrinkage-compensating cement concretes exposed to corrosive environments. This included a long-term corrosion monitoring of reinforced concrete specimens made with different dosages of shrinkage-compensating cement. In addition to finding the corrosion rate of embedded steel bars, air permeability, capillary absorption, and chloride diffusion tests were conducted to determine the transport properties of the concretes made with this type of cement. The experimental test results were then further supported and explained using mercury intrusion porosimetry analyses.

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.

Long-Term Corrosion Monitoring by Titanium Wire Sensor and Vibration-Based Energy Harvester

Long-Term Corrosion Monitoring by Titanium Wire Sensor and Vibration-Based Energy Harvester

Corrosion Potential Sensor for Remote Monitoring of Civil Structure Based on Printed Circuit Board Sensor

We present a printed circuit board-based wireless inductively coupled corrosion potential sensor for monitoring corrosion of steel-reinforced concrete civil infrastructure. The sensor is a passive LC coil resonator whose resonant frequency varies owing to the corrosion potential produced by two electrodes connected across a voltage-controlled capacitor. The junction capacitance of the voltage-controlled capacitor also varies according to the potential generated by the two electrodes, which is in turn responsible for changing resonant frequency of the sensor. The two electrodes are a stainless steel reference electrode and a steel reinforcement electrode. An external interrogator coil coupled with the sensor coil monitors the sensor resonant frequency shift remotely by measuring the impedance change from the source end. The sensor has a sensitivity of ~1.2 kHz/mV both before and after it is embedded in the cement-based mortar used for testing the sensor. The sensor can be used to sense the corrosion susceptibility of existing structures by embedding the corrosion electrodes in new grout within a small slot formed in an existing structure. Using this approach, weight concentrations of NaCl mixed in cement-based mortars of greater than 2%-3% were detected. Accelerated corrosion tests on embedded sensors in simulations of both new and existing structure demonstrated corrosion potential resolution of less than 10 mV and an uncertainty of less than 50 mV. The sensor is simple in design, inexpensive, and passive making it a battery-less option for long-term corrosion monitoring, and widely deployable for civil structure.

Heterogeneous tiny energy: An appealing opportunity to power wireless sensor motes in a corrosive environment

Reinforcing steel corrosion is a significant factor leading to the durability deterioration of reinforced concrete (RC) structures. The on-line monitoring of the corrosion of RC structures in a long-term, human-free manner is not only valuable in industry, but also a significant challenge in academia. This paper presents the first of its kind corrosion-monitoring approach that only exploits three heterogeneous tiny energy sources to power commercial-off-the-shelf wireless sensor motes such that the corrosion-related data are automatically and autonomously captured and sent to users via wireless channels. We first investigated the availability of these three tiny energy sources: corrosion energy, a cement battery, and a weak solar energy. In particular, the two former energy sources inherently exist in RC structures and can be generated continually in the service-life of RC structures, which beneficial for the prospects of long-term corrosion monitoring. We then proposed a proof-of-concept prototype, which consisted of a Telosb wireless sensor mote and an energy harvester in order to evaluate the feasibility and effectiveness of the ultralow-power ambient energy as a type of power supply in corrosion monitoring applications. The critical metrics for the holographic monitoring of RC structures, including electrochemical noise, humidity and temperature, were successfully acquired and analysed using a post-processing program. This paper describes a unique and novel approach towards the realisation of smart structural monitoring and control system in the practical engineering.

Fourier transform infrared spectroscopy in long-term corrosion monitoring of the interaction between a commercial aluminum sheet and carbon tetrachloride at room temperature

The possibilities of diffuse and specular reflectance Fourier-transform infrared spectroscopy in long-term corrosion monitoring are studied. A 15-week period of interaction between carbon tetrachloride and a commercial aluminum sheet is followed. Analysis of the results obtained reveals a complex and multistage character of the interaction between CCl4 and aluminum surface. The final product of the reaction is shown to be chlorine-containing hydrocarbon, which is strongly bound to the metal surface.