Advanced Techniques for Detecting and Mitigating Corrosion in Reinforced Concrete Structures

Advanced Techniques for Detecting and Mitigating Corrosion in Reinforced Concrete Structures

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Understanding Corrosion Prevention in Concrete Structures

Corrosion in reinforced concrete is a pervasive issue that compromises the structural integrity and longevity of infrastructure. This phenomenon primarily stems from the deterioration of steel reinforcement within the concrete matrix. The resultant rust formation is bigger than steel, causing cracking, spalling, and eventual weakening of the concrete.

Failure to mitigate corrosion can lead to catastrophic structural failures, economic losses, and increased maintenance costs. Therefore, implementing advanced detection and mitigation strategies is essential for preserving the functionality and lifespan of these structures.

Mechanisms of Corrosion in Reinforced Concrete

Understanding the mechanisms behind corrosion in reinforced concrete is crucial for developing effective prevention and remediation strategies.

Corrosion in reinforced concrete is fundamentally an electrochemical process involving anodic and cathodic reactions. At the anodic sites, iron from the steel reinforcement oxidizes, releasing electrons. These electrons travel to the cathodic sites, where they reduce oxygen in the presence of water, forming hydroxide ions. This redox process results in the formation of iron oxides and hydroxides.

Two primary factors accelerate the corrosion process in reinforced concrete: chlorides and carbonation. Chlorides, often originating from de-icing salts or marine environments, penetrate the concrete and disrupt the passive oxide layer protecting the steel. Carbonation occurs when carbon dioxide from the atmosphere reacts with the hydrated cement paste, reducing the alkalinity of the concrete and allowing corrosion to initiate.

Advanced Techniques for Detecting Corrosion in Reinforced Concrete

Advanced detection techniques are crucial for identifying corrosion at its early stages, allowing for timely intervention. While tapping with a hammer can tell us much about the condition of a structure, more advanced detection techniques include:

1.    Ground Penetrating Radar (GPR)

Ground Penetrating Radar (GPR) utilizes electromagnetic waves to identify anomalies within concrete structures. By analysing the reflected signals, GPR can detect areas of corrosion-induced damage, such as voids and delamination, without causing any damage to the structure. This non-destructive method offers a rapid and efficient means of assessing the condition of reinforced concrete.

2.    Half Cell Potential Mapping

Half Cell Potential Mapping measures the corrosion activity in concrete structures. Concrete is removed around a suitable bar, and the resistance is checked between two separated points to determine a continuous flow of current. The area is mapped by taking readings across a grid of points, thus allowing us to assess for potential corrosion and the need for further investigation.

 

corrosion mapping is an effective method for assessing the severity of corrosion activity in concrete structures. It is the most well-known procedure to identify the likelihood of active corrosion; however, the test does not provide any information about the kinetics of corrosion activity.

Mitigation Strategies

Mitigating corrosion requires innovative approaches that address the root causes of corrosion in reinforced concrete and prevent further deterioration.

The most common method is Cathodic Protection, which controls corrosion by converting the anodic sites on the steel surface to cathodic sites. This is achieved by applying an external electrical current or by connecting a more easily corroded sacrificial anode to the steel. This technique effectively halts the corrosion process and prolongs the service life of the structure.

Another commonly used strategy is to add chemical compounds that act as corrosion inhibitors to the concrete mix or applied to the surface to impede the corrosion reactions. These inhibitors function by forming a protective film on the steel reinforcement, thus preventing the ingress of aggressive ions like chlorides. Various organic and inorganic inhibitors are available, each with specific mechanisms of action, though there is much debate as to how they work (repassivation or as a pore blocker).

Advanced Coatings serve as a barrier to protect steel reinforcement from environmental aggressors. These coatings, often comprising epoxy, polyurethane, or zinc-rich formulations, provide excellent adhesion and durability. The application of such coatings is a proactive measure to prevent the initiation and progression of corrosion – waterproof first, and worry about other things after.

Materials and Technologies in Corrosion Mitigation

The development of advanced materials and technologies is also proving critical in enhancing corrosion resistance in concrete strictures.

High-Performance Concrete (HPC) exhibits superior durability and resistance to environmental stressors due to its optimized mix design and enhanced material properties. The use of supplementary cementitious materials like fly ash, slag, and silica fume in HPC improves its impermeability, thereby reducing the risk of chloride ingress and carbonation.

Self-Healing Materials (such as NitCal) represent a another approach to corrosion mitigation. These materials can autonomously repair cracks and micro-damage within the concrete matrix through mechanisms such as autogenous healing, encapsulated healing agents, or microbial action. This self-repair capability significantly enhances the longevity and resilience of concrete structures.

Nanotechnology Applications in corrosion mitigation involve the use of nanomaterials to enhance the protective properties of coatings and concrete. Nanoparticles such as nano-silica, nano-clay, and carbon nanotubes can improve the mechanical strength, density, and durability of concrete, offering a robust defence against corrosive elements.

Future Directions in Corrosion Management

Several real-world examples illustrate the successful application of advanced corrosion detection and mitigation techniques. For instance, the use of EIS in monitoring the corrosion state of bridges in coastal regions (such as the Machico Stayed Bridge project in Portugal) can provide valuable data for maintenance planning. Similarly, the implementation of cathodic protection systems in historic structures has preserved their integrity for future generations.

However, the future of corrosion management lies in the continuous evolution of technologies and methodologies. In this regard, the importance of corrosion science cannot be overstated. Emerging research in the field of corrosion management is focused on developing more efficient and sustainable solutions. Innovations such as bio-inspired materials, smart monitoring systems, and environmentally friendly inhibitors will enhance corrosion resistance and extend the lifespan of concrete structures.

Though anode materials, monitoring devices etc have remained largely unchanged since the early 1990s, potential technological developments include the integration of artificial intelligence and machine learning algorithms to predict corrosion patterns and optimise maintenance schedules. Additionally, future advances in material science are expected to yield new high-performance composites and coatings with unparalleled protective properties.

By leveraging advanced detection techniques, innovative mitigation strategies, and cutting-edge materials, we can significantly mitigate the impact of corrosion on reinforced concrete structures. This requires a proactive approach that not only ensures the durability and safety of infrastructure but also contributes to sustainable development by reducing the need for frequent repairs and replacements.

The Institute of Corrosion’s (ICorr) Corrosion Science Division (CSD) is at the heart of promoting advances in corrosion knowledge and capability in the UK and around the world. Become a member of ICorr today and join the CSD to play your part in the scientific advance of the corrosion industry.

Pipeline Corrosion Detection and Management – An Essential Overview

Pipeline Corrosion Detection and Management – An Essential Overview

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Innovation, Integrity, and Expertise in Pipeline Sustainability

Pipeline corrosion is a and inescapable phenomenon that represents one of the most significant challenges for many industries. Manifesting in a variety of forms, it impacts longevity and integrity of liquid and gas transportation systems. Consequently, significant investment is made in the detection and identification of pipeline corrosion and its management.

In this article, we provide an overview of what is – and will continue to be – a critical field in pipeline management.

Why Is Management of Pipeline Corrosion So Important?

When poorly managed, the ramifications of pipeline corrosion can be extensive and influence safety, environmental and economic aspects of an operation.

Economically, pipeline corrosion leads to immense costs related to maintenance, repairs, and lost efficiency. For example, there are estimated to be around 2.15 million kilometres of oil and gas pipelines around the world, and corrosion is the most important factor in pipeline integrity. In the United States alone, the annual yearly cost of pipeline corrosion is estimated at $7 billion.

A real-life example of the potential economic impact of pipeline corrosion was demonstrated in the Alaska Pipeline system where, in 2011, severe corrosion led to a spill of approximately 200,000 gallons of oil – despite pipeline corrosion caused by faulty coating having been identified 20 years earlier.

From a safety perspective, the stakes are incredibly high. Corrosion can compromise the structural integrity of pipelines, leading to failures that might cause explosions, fires, and oil spills. These incidents not only endanger human lives, but also have devastating effects on the environment. In a study of 1,063 pipeline accidents, 21% were found to have been caused by corrosion.

Effective detection and management of pipeline corrosion is not simply a case of technical and regulatory compliance. Fundamentally, it is an ethical imperative regarding the safeguarding and wellbeing of employees, surrounding environments, and local communities. Consequently, regulatory bodies across the globe impose stringent requirements for corrosion management to mitigate these risks.

Key Methods for Detecting Pipeline Corrosion

Detecting, measuring, and monitoring pipeline corrosion involves a multifaceted approach that includes non-destructive testing, electrochemical probes and sacrificial coupons

Corrosion coupons – sacrificial metal strips exposed to pipeline conditions – are analysed to determine corrosion rate within the pipeline.

·       Non-Destructive Testing (NDT) Methods

NDT methods help to provide a more comprehensive view of pipeline corrosion. Techniques such as acoustic emission (AE), magnetic flux leakage (MFL), and liquid penetrant inspection enable early detection without damaging pipelines. Advanced NDT methods include:

  • Visual Inspection, despite being the most basic form of corrosion detection is a very valuable inspection tool. It involves regular surveys and manual inspections of accessible pipeline sections.  Of course this can only be used on the external surfaces of pipelines.

Techniques that allow both internal and external inspection:

  • Radiographic Testing (RT) is an extension of visual testing involving the use of X-rays or gamma rays to capture sub-surface images that reveal corrosive damage.
  • Ultrasonic Testing (UT), which employs high-frequency sound waves to detect imperfections or changes in material properties like the use of UT in medical applications.
  • Electromagnetic Testing (ET), which utilises electromagnetic induction to detect surface and sub-surface irregularities

In addition, Intelligent pigs – often referred to as ‘Smart Pigs’ – can travel internally along pipelines to detect anomalies using methods like ultrasonic testing and magnetic sensors, providing comprehensive data regarding the condition of the pipeline.  They can often provide inspection of almost 100% of both the internal and external surfaces of a pipeline.

Other forms of robots such as drones and crawlers can also be fitted with the above technologies to carry out inspections in locations that are difficult to reach.

The integration of modern technologies such as the Internet of Things (IoT) and predictive analytics represent a revolutionary step in corrosion management. Data is continuously transmitted in real time to be analysed so that potential failure points can be identified. This will allow pre-emptive repairs and significantly reduce downtime.

Corrosion coupons – sacrificial metal strips exposed to the internal pipeline conditions – are analysed to determine corrosion rate within the pipeline.

Electrochemical Probes can be inserted into a pipeline to measure the corrosivity of the fluid inside it.  They can provide a continuous output of corrosion rates that can be fed to a pipeline control room and corrosion engineers.

Pipeline Corrosion Prevention Techniques

When taking action to prevent corrosion of pipelines, utilising a combination of techniques and methods is crucial. Such methods include:

·       Cathodic Protection

An electrochemical process that reduces the oxidation within metal pipelines by making them the cathode of an electrochemical cell. The main cathodic protection techniques are to use sacrificial anodes or impressed current cathodic protection.  This technique is primarily used to protect the external surface of a pipeline – usually in combination with coatings and linings.

·       Coatings and Linings

Coatings and linings can be made from organic, metallic and inorganic materials.  They provide   an anti-corrosive layer that acts as a barrier between the pipe material and the corrosive environment. When designing pipelines to minimise the risks of corrosion, it’s crucial to select materials that are inherently resistant to corrosion.  They can be used on both internal and external surfaces of pipelines.

·       Corrosion Inhibitors

Corrosion inhibitors are the most widely used method for protecting the internal surfaces of pipelines.  They are added to the pipeline fluids and absorb onto the metal surface to provide a barrier to corrosion.

Future Trends in Corrosion Management of Pipelines

Corrosion detection and management of pipelines has evolved rapidly in recent years, and will have to continue to do so – to tackle new corrosion threats such as the transportation of hydrogen and carbon dioxide from carbon capture plants. From regulatory frameworks to materials science to sensing technologies, corrosion science and corrosion engineering continue to advance.

·       Advances in Material Science

The development of new alloys and composite materials is pivotal in combatting pipeline corrosion. These materials are engineered to endure harsh environments and aggressive chemicals that accelerate corrosion in conventional materials.

Additionally, the incorporation of nanotechnology into material fabrication has given birth to nano-coatings and nanocomposites that enhance durability and resilience by improving barrier properties and reducing molecular wear and tear.

A key breakthrough has been in the use of graphene, which acts as an impermeable barrier to gases and liquids, minimising oxidation, which is a key factor in corrosion.

·       Enhanced Sensing Technologies

Technological innovations in sensing technologies are revolutionising corrosion management by enabling more precise and comprehensive monitoring capabilities. Modern sensors now incorporate features like higher resolution, greater coverage areas, and advanced data analytics to detect and predict corrosion sites before they manifest into larger issues.

For example, fibre optic sensors provide real-time data on pipeline integrity by detecting changes in temperature, pressure, and structure. These sensors are immune to electromagnetic interference, making them versatile for diverse environments. Moreover, drones equipped with hyperspectral imaging sensors can perform aerial surveys to detect corrosion under insulation or in inaccessible areas.

·       Regulatory and Standards Evolution

The evolution of international standards and regulatory requirements is crucial in pushing the envelope of what is technologically feasible and economically viable in corrosion management. Updating of standards ensures that the newest technological advances and best practices are implemented to safeguard public and environmental health.

Advancing Knowledge and Expertise in Corrosion Management

As the complexities of pipeline corrosion evolve, so too must the expertise of those tasked with managing it. The Institute of Corrosion (ICorr) plays a crucial role in this dynamic landscape. By sharing knowledge, expertise, and best practices, ICorr ensures that corrosion professionals are well-prepared to tackle current and future challenges. We are also at the forefront of policy discussion, giving our members a voice in the future regulation of the industries in which they operate (as demonstrated by our sponsorship of the Reuse, Repair, Replace Conference).

Our commitment to education and continuous professional development is evident through our industry-leading training programs. These are designed and delivered to elevate the technical competence of personnel across the corrosion industry. Through initiatives such as our membership pages, social media, Corrosion Management magazine and more, we provide a collaborative environment in which all our members (and the wider corrosion community) can benefit from insight and innovation in corrosion science and corrosion engineering.

In an era where technological advancements are critical to economic viability and environmental stewardship, the role of institutions like the Institute of Corrosion is indispensable. Through its efforts, ICorr not only contributes to the global economy but also fortifies the industry’s capacity to manage corrosion effectively, safeguarding infrastructure and ecosystems alike.

Here’s feedback from a recent Level 2 Pipeline Coating Inspector certification course, presented to the Quality Team at Tenaris in Villamarzana, Italy:

“This course has been a unique opportunity to enhance our knowledge and formalize the highest level of competency within the company, as recognized by ICorr, which selected us for the deployment of this new training.”

To learn more about the Institute of Corrosion, our membership schemes, and our comprehensive training packages, email admin at ICorr.

Institute of Corrosion 2024 AGM at Neville Hall

Institute of Corrosion 2024 AGM at Neville Hall

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Photo 1 The Historic Lecture Theatre at Neville Hall

On Wednesday 13th November the North-East Branch of the Institute of Corrosion hosted the Institute of Corrosion 2024 AGM at Neville Hall in Newcastle upon Tyne.

The day commenced with a Technical Offshore Wind Program, followed by the AGM and concluding with an evening dinner. Almost 70 people from all over the UK attended the Technical Program and 60 attended the evening dinner, attendees included the ICorr Council, Sustaining Members, Professional members, general members and potential future members. The day was a great success with the variety of engaging content keeping the attendees entertained for almost 9 hours from start to finish.

Photo 2 The Lord Mayor of Newcastle upon Tyne Opening the Technical Program

Matt Fletcher, Chair of the North-East Branch of ICorr, opened proceedings and who was followed by the formal opening of the Technical Program by the Lord Mayor of Newcastle, who welcomed everyone to Newcastle and described how offshore wind and the project to re-paint the Tyne Bridge brought valuable jobs to the region. Lord Mayor also explained that as he did not have his “driver” available he was unable to wear his full collection of Mayoral Medals as they were too valuable to be worn in public without the extra security of his “driver”!

The Offshore Wind Technical Program then opened, consisting of 4 presentations:

Environmental considerations for offshore wind foundations corrosion protection.
Dr. Anthony Setiadi Chief Consultant / Associate Director Wood Thilsted

Photo 3 Dr Anthony Setiadi of Wood Thilsted presenting

Anthony described how the offshore wind industry growth is accelerating as the world is pushing towards renewable energy sources. These wind turbines need to be installed on foundations located in aggressive environments and are prone to corrosion if not protected and / or designed with corrosion in mind. There are various offshore wind foundation types, such as, monopiles, jackets tetrabases, gravity bases and floating structures. The presentation discussed what level of protection is required, what the options are and how would all of this impact the structural integrity throughout the design life, also how fabrication, transport and installation limitations would affect the corrosion protection design. Anthony explained how equally important, the environmental considerations need to be taken into account with respect to carbon equivalent in producing and protecting these foundations, as well as the potential byproducts expected. In discussing the creation of habitats for nature, Anthony made an interesting point, that if habitats are created on the foundations, what happens to these environments when the foundation is decommissioned in the future?

Assessment of Thermal Spray Aluminium Coating in Synthetic Seawater By Using Complementary Techniques

Dr. (candidate) Adriana Castro Vargas Research Associated – Materials Innovation Centre University of Leicester and NSIRC

Photo 4 Dr Adriana Vargas of the Materials Innovation Centre University of Leicester presenting

Adriana presented the results of her PhD that used complementary techniques, such as in-situ imaging and an analytical rotator, to understand the performance of thermally sprayed aluminum (TSA) coating in simulated marine immersion service. The experimental work involved evaluating TSA in quiescent and flowing synthetic seawater at room temperature. The coating (300µm thick) was obtained by twin-wire arc spraying of 1050 aluminium alloy on an S355 carbon steel substrate. In quiescent condition, TSA-coated steel samples were evaluated by the optical analysis of sequential images captured in-situ: (i) with defects machined before immersion (5% of exposed steel surface); and (ii) with a defect machined after 35 days of immersion (10% of exposed steel surface). When the defect is machined before the immersion, initial dissolution of iron occurs until the air-formed oxide layer degrades, the electrolyte penetrates the coating, and the aluminium surface is activated. Conversely, when the defect is created after immersion, the aluminium activates rapidly, and the system reaches the range of protective potentials (according to DNV-P-B401) providing immediate protection to the exposed steel. In flowing synthetic seawater, cylindrical coupons were tested in an analytical rotator at 50 rpm and 600 rpm for 10 days. Open Circuit Potential (OCP) and Linear Polarisation Resistance (LPR) measurements were carried out to assess the flow velocity effect and calculate the corrosion rate.

An introduction to the Offshore Renewable Energy (ORE) Catapult and its key role in advancing and derisking technology in offshore wind.

Mr. Tom Chaplin Marketing Manager Offshore Renewable Energy Catapult

Tom Chaplin provided an introduction to the Offshore Renewable Energy Catapult and described the key role it plays in advancing and derisking technology in offshore wind. ORE Catapult is one of the world’s leading offshore renewables technology centres, with an unrivalled set of test assets that aim to accelerate the creation and growth of UK companies in the offshore renewable energy sector. Established in 2013, ORE exists to accelerate the development of offshore wind, wave and tidal energy technologies in the UK. Through its world-class testing and research programmes and its unique centres of excellence, ORE works with industry, academia and government to improve technology reliability and enhance knowledge, directly impacting the cost of offshore renewable energy. ORE delivers products and services in four main areas: research, engineering, testing and validation, and supply chain growth.

Photo 5 Tom Chaplin of ORE Catapult presenting

Tom showed the scale of the ORE Catapult testing facilities showing a video of testing a 107m blade (which needed to be cut down to 100m to fit in the test facility) and the 14GW powertrain, which as a result of the testing, had its capacity increased. Tom also revealed plans to increase the capacity at ORE Catapult to be able to handle wind turbines well into the future with capability to test blades up to 150m long (and expansion potential to 180m) and a significant increase in drive train capacity to 23MW (with potential expansion to 28MW). After the presentation Tom was asked about catastrophic failure during testing, although unable to share images, Tom said it had happened and was quite dramatic. All was not lost as the fractured blade provided insightful data on blade failure to the owners

Development of ISO 25249 – Corrosion protection of offshore wind structures
Mr. Simon Daly Consultant – Energy & Infrastructure Safinah Limited

Photo 6 Questions following Simon Daly’s (Safinah) presentation

Simon described how a series of parts of a new international standard, ISO 25249, are currently being worked upon. The standard will address the issues of developing a corrosion protection approach for the protection of offshore wind farms. With the growth in offshore wind will come the need for large scale construction of assets which will be placed in a corrosive offshore environment. Whilst the corrosion of steel structures offshore is well documented through experiences in the oil and gas industry the offshore wind energy has encountered its own challenges when it comes to providing corrosion protection. The ISO 25249 standard will address key issues and develop a framework for a more standardised approach to the selection, execution and operation of a variety of different corrosion protection methods. Simon presented on behalf of the program managers for the first 5 parts of this new standard the development of which will shortly commence within the International Standards Organisation (ISO) framework. During the questions after the presentation the sharing of experiences gained in the Oil and Gas industry was discussed, it was generally agreed that to prevent mistakes from 30 years ago being repeated, experiences should be reviewed and shared. It was hoped that with more of the traditional Oil and Gas companies entering the offshore wind market that this will be more likely to take place.

Following the Technical Program the ICorr AGM took place, details of the AGM can be found in the AGM minutes. At the AGM Stephen Tate passed on the Presidency of ICorr to Yunnan Gao and Yunnan passed on the Vice-Presidency to Anthony Setiadi.

Photo 7 New Vice President – Dr Anthony Setiadi, New President – Dr Yunnan Gao, Past President – Stephen Tate

The evening saw a three-course dinner, enjoyed in the library at Neville Hall. As can be seen in the photographs, the library is a beautiful wooden clad room, with many original features such as elevated bookshelves, bookshelves hidden behind wooden doors and stained-glass windows. A jazz band played throughout the evening and the dinner was opened by the new president of ICorr – Dr Yunnan Gao.

Photo 8 Dinner in the impressive Library at Neville Hall

Feedback following the event was overwhelmingly positive:
• “NE Hospitality is famous and you certainly lived up to that.” – Stephen Tate: outgoing ICorr President.
• “Please accept my thanks for the superb organisation and excellent day yesterday.” – Brian Wyatt of CPGB and Council.
The Chair of the NE Branch of ICorr grateful thanks the NE Branch Committee for all their hard work in creating a most successful day, all are volunteers and worked tirelessly to make the event a success – Simon Daly, Patrick Johnson, David Mobbs, Bruno Ravel, Barry Turner and Josie Watson

Future Meetings
Due to a date clash with London Branch Dinner, NE Branch will now hold its Xmas (Branch) event at the end of January 2025.

There will be a tour of the Newcastle Castle Keep – the cost for which will be £20 a head.
Please contact nechair@icorr.org for further details.

Advanced Techniques for Detecting and Mitigating Corrosion in Reinforced Concrete Structures

Long-term Durability of Concrete Structures in Corrosive Environments

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Understanding the Impact of Corrosive Environments on Concrete

The longevity of concrete structures is crucial to the safety and functionality of buildings, bridges, and other infrastructure. In corrosive environments, where exposure to aggressive agents accelerates degradation, maintaining the durability of concrete is critical.

In this article, we examine how corrosive environments impact concrete structures and discuss essential measures to mitigate damage caused by corrosion.

What Causes Corrosion in Concrete Structures?

Corrosion in concrete is driven by chemical and physical processes.

Steel in concrete is, strangely, usually at a low risk of corrosion.  The highly alkaline nature of concrete produces stable microscopic surface corrosion that prevents any chemical reactions.  Unfortunately, high levels of chlorides or sulphides can penetrate this layer, or carbon dioxide can neutralise the pH of the concrete; both of which allow the steel bars to start rusting.    

Physically, factors like freeze-thaw cycles and abrasion can exacerbate the wear and tear, further accelerating the degradation process.

Understanding the Corrosive Environment

Primarily, we are concerned with three types of environments in which concrete structures are built:

1.    Marine Environments

Marine environments pose significant challenges due to the high salinity of seawater. Saltwater spray and immersion expose concrete to chlorides, leading to rapid reinforcement corrosion.

2.    Industrial Environments

Industrial areas are often laden with pollutants.  Carbon dioxide reacts with concrete, reducing its pH and allowing the steel to corrode.

3.    Urban Environments

Urban settings, and roadways (especially highway bridges) with their elevated levels of carbon dioxide from vehicle emissions, contribute to carbonation. This process lowers the alkalinity of concrete, diminishing its protective capabilities against steel corrosion.

Strategies for Mitigating and Preventing Corrosion in Concrete

From structural design through materials selection and to monitoring and maintenance, there are a multitude of strategies that we can employ to mitigate and prevent corrosion in concrete.

Structural Design Considerations

Understanding that corrosion can significantly reduce the load-bearing capacity of concrete structures, architects and designers must ensure that structures maintain their integrity and safety throughout their service life.

Incorporating durability into the design phase involves selecting appropriate materials, specifying protective measures, and designing for environmental conditions. Ensuring adequate cover to reinforcement and proper drainage systems are also vital.

Materials and Mix Design for Enhanced Durability

When considering materials to be used in the construction of concrete structures, designers can incorporate:

·        High-Performance Concrete (HPC)

High-performance concrete (HPC) is engineered to exhibit superior properties, including lower permeability and higher strength. These characteristics make HPC more resistant to ingress of corrosive agents.

·        Supplementary Cementitious Materials (SCMs)

Incorporating materials like fly ash, slag, and silica fume into concrete mixes can significantly enhance durability. SCMs reduce the permeability and improve the microstructure of concrete. However, they can also adversely affect the pH, and so must be used with caution.

Use of Protective Coatings and Sealants

Epoxy coatings, polyurethane sealants, and silane-siloxane treatments are commonly used to protect concrete surfaces. These coatings create a barrier that prevents the ingress of water and harmful chemicals.

Proper surface preparation and application methods are crucial for the effectiveness of protective coatings. Techniques such as spray application, brush application, and trowel application are employed based on the specific requirements of the project.

However, while protective coatings provide immediate protection, their long-term performance depends on factors like environmental conditions, application quality, and maintenance practices.

Monitoring and Maintenance Strategies

When it comes to corrosion in concrete, no concrete structure is ‘set and forget. We must continually monitor for structural integrity and instigate effective maintenance regimens. To achieve this, we turn to methods such as non-destructive testing, routine inspections, and predictive maintenance:

  • Non-destructive testing methods include techniques such as half-cell potential mapping, ground-penetrating radar, ultrasonic pulse velocity, and infrared thermography are used to assess the condition of concrete structures without causing damage. These methods help to identify early signs of corrosion and other defects.
  • Regular inspections, such as visual inspections combined with more detailed testing, help to detect and address issues before they escalate, thus ensuring that maintenance can be planned and executed effectively. In particular, the expansive nature of rebar corrosion can cause cracking and spalls before the structure loses strength (mostly) and this can act as an effective early warning system.
  • Advanced predictive models use data from inspections and monitoring to forecast future deterioration. This proactive approach enables timely interventions, reducing the risk of unexpected failures.

Corrosion Control in Infrastructure Cannot be Ignored

Failures of concrete structures because of corrosion in concrete can have disastrous consequences. Analysing failures, such as the collapse of the Morandi Bridge in Genoa that caused 43 people to lose their lives, highlights the importance of proper design, materials selection, and maintenance. We cannot and must not ignore corrosion control in infrastructure. The lessons we learn guide future practices to help us avoid similar outcomes.

When we apply all that we have learned, we can create structures and complete projects like the Burj Khalifa and the Millau Viaduct that showcase the successful application of advanced materials and techniques.

In summary, ensuring the long-term durability of concrete structures in corrosive environments requires a multifaceted approach. From material selection and mix design to protective measures and maintenance strategies, each aspect plays a critical role in enhancing the resilience and longevity of concrete infrastructure. Continuous research and innovation will further bolster our ability to combat the challenges posed by corrosive environments. Continuous upgrade and certification will ensure the durability of your career in the concrete environment.

The Institute of Corrosion supports learning and advancement in all fields within the corrosion industry. These include:

Just as our concrete infrastructure should be, these courses are designed to be future-proofed, continually updated as we learn more, and regulations and standards evolve to ensure that all we learn is embedded into best practice.

Mastering Marine and Offshore Coating Inspection: Your Guide to Qualifying at Level 1

Mastering Marine and Offshore Coating Inspection: Your Guide to Qualifying at Level 1

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Preparing for the Protective Coatings Inspector Level 1 Course

Protecting marine and offshore structures from corrosion is vital to the integrity of our oil and gas industry. Correctly applied and maintained coatings are a critical component in this, not only safeguarding against corrosion but also significantly extending the lifecycle of installations in harsh marine environments.

To ensure the effectiveness of coating systems, competent coating inspection is essential. Coating Inspectors are in high demand – it’s a highly rewarding role with great responsibility, and worldwide opportunities.

The Level 1 Coatings Inspection Course equips you with knowledge and skills to oversee and implement protective coatings systems. However, qualifying at Level 1 is not a cakewalk. It takes hard work and a strategic approach.

Based on feedback from previous course attendees, we’ve identified key strategies and tips to help increase your chances of success at this crucial stage of a career in coating inspection.

Preparing for the Protective Coatings Inspector Level 1 Course

You’ll be covering a lot of ground as you prepare to kickstart your career with Level 1 Coating Inspector training. Topics include:

  • Protective Coating Application and Spray Painting
  • Abrasive Blast Cleaning
  • Coating Inspection and Inspection Equipment
  • Marine Coatings

You’ll also explore QA, QC, and the basics of inspection, providing a comprehensive understanding of normative documents, corrosion of iron and steel, surface preparation for ferrous materials, and much more.

Before attending the course, we recommend that you become acquainted with its contents, and familiarise yourself with key concepts, such as tools and techniques used in the industry, how materials respond to different environmental conditions, and the protective qualities of various coatings. Having a foundational knowledge in these areas will prepare you for the deeper dive into the world of coating inspection that the Level 1 course delivers.

Best Practices for Engaging with Course Material

How you use the course materials is crucial – the right learning strategies will not only enhance your learning experience, but also make the course more enjoyable. We’ve condensed feedback into three categories:

1.    Effective Notetaking and Concept Mapping

Structured note-taking methods like the Cornell Note-Taking System help you organise and summarise key information efficiently. You might also employ concept mapping by creating visual relationships between course topics – this is particularly useful when linking theory to practical applications to improve your problem-solving skills.

2.    Utilising Resources Effectively

Consider the content of the course and the topics you will be covering, and supplement this with recommended reading that might include texts on materials science, corrosion protection, and coating technologies.

Don’t neglect the value of interactive tools – if you’re taking the online version of the course, these include the online modules and video tutorials, which can help to deepen your understanding of the subject matter, as well as cater for various learning styles.

3.    Active Learning

Finally, participate in class discussion and workshops. Ask questions and collaborate with others – this all helps to enhance your understanding and knowledge retention.

In practical sessions, ensure that you actively seek to associate application with the foundational theories, to cement your learning and prepare you for fieldwork.

Master Your Skills During Practical Sessions

There will be opportunities to optimise your hands-on training experience in supervised practical sessions to experience the environmental and logistical challenges you’ll face in the field. You should expect structured guidance and step-by-step demonstrations in using various equipment, across realistic tasks such as evaluating surface preparations, applying coatings, and conducting post-application inspections.

To get the most from your practical sessions, you should:

  • Take every opportunity to handle materials and tools; the tactile experience is invaluable
  • Ask questions to clarify procedures and rationales to deepen your understanding of each task
  • Collaborate with your peers to gain new insights and reinforce your knowledge
  • Relate practical tasks back to the theory to help understand why certain methods are preferred
  • Note how coating performance is impacted by environmental performance

Techniques for Excelling in the Exam

The exam is held on a separate day after the end of your course. However, we all know that exams can be funny things – nerves may play a part, and passing to qualify is not guaranteed. Your success depends upon preparation and exam strategy. Here are our tips to help you qualify at Level 1:

·       Create a Structured Revision Plan

Allocate specific times for different topics according to their complexity and your proficiency. Stick to a consistent schedule to build a routine.

·       Consolidate Revision

Break down the course content into manageable topics and review them systematically. Use summary sheets and flashcards for key terms and concepts.

·       Practice Your Knowledge Recall

Test your understanding regularly by practicing with past exam questions or creating your own quizzes. This reinforces learning and identifies areas needing further review.

·       Manage Your Time

Figure out how much time to spend on each question, and prioritise those that you find easiest to secure marks quickly.

·       Understand Questions Before Answering

Break down complex questions to understand exactly what is asked. Only then should you tackle the answer.

Choose the Course That Suits Your Preferred Learning Style

We all have diverse preferences, schedules, and learning styles. Whether you thrive in the dynamic atmosphere of a classroom or prefer the flexibility of self-paced study, we partner with leading training providers to align with your unique educational needs and career goals:

·       Classroom Learning with IMechE Argyll Ruane

Experience the immersive environment of classroom learning in Sheffield, equipped with cutting-edge facilities. IMechE Argyll Ruane offers a comprehensive five-day course that covers all aspects of Level 1 certification. This option is ideal for those who benefit from face-to-face interactions and immediate expert feedback.

·       Online Learning with Corrodere Academy

Embrace the flexibility of online learning with Corrodere Academy, where you can progress at your own pace. You have 12 months to complete 40 hours of interactive, professionally curated content. This format is perfect for those who need to balance their educational pursuits with professional or personal responsibilities.

The Institute of Corrosion has chosen IMechE Argyll Ruane and Corrodere Academy as preferred training providers because they deliver the highest standards in global corrosion training.

Whether opting for classroom learning or online courses, rest assured that you are receiving top-tier training designed to equip you for the supervisory challenges of a Coating Inspector role.

Your Pass to a Successful Career as a Coating Inspector

Mastering Level 1 Coating Inspection equips you to protect marine and offshore structures from corrosion, taking a course that blends theory with practical skills. With commitment and a strategic approach, you’ll not only gain certification but also lay a strong foundation for a successful career in coating inspection.

For more information, and to discuss which course is best for you, contact ICorr’s admin team by email today.

Advanced Techniques for Detecting and Mitigating Corrosion in Reinforced Concrete Structures

The Significance of Chlorides and Carbonation in the Corrosion of Reinforced Concrete Structures

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​Strategies to Prevent and Mitigate Reinforced Concrete Corrosion

Reinforced concrete (RC) structures provide the backbone for infrastructure such as bridges, buildings, and highways. This composite material, consisting of concrete and steel reinforcement, combines the compressive strength of concrete with the tensile strength of steel, yielding a robust and durable construction material.

However, despite its inherent strength, RC is susceptible to corrosion, a process that can significantly compromise structural integrity. Understanding the mechanisms, contributors, and impacts of reinforced concrete corrosion is crucial when designing structures that are both sustainable and safe. Two factors that we must always consider are chlorides and carbonation.

Mechanisms of Reinforced Concrete Corrosion

Corrosion in reinforced concrete is fundamentally an electrochemical process involving anodic and cathodic reactions. At the anodic site, iron from the steel reinforcement oxidizes to form iron ions, releasing electrons. These electrons travel through the steel to the cathodic site, where they reduce oxygen and water to form hydroxyl ions.

The steel reinforcement within concrete can act as both the anode and cathode in the electrochemical cell, making it a prime site for corrosion. Because its deterioration directly affects the structural performance of the concrete, the integrity of thus steel is crucial.

Chlorides in Concrete

Chlorides in concrete can originate from various sources, including de-icing salts, seawater, and admixtures. These chlorides permeate the concrete matrix and reach the reinforcement, initiating and propagating corrosion.

Chlorides penetrate concrete through mechanisms like diffusion, capillary action, and permeation. The transport rate depends on the concrete’s porosity, moisture content, and environmental exposure.

A critical factor is what is known as the chloride threshold level – the concentration at which corrosion initiates. This level depends on factors such as the type of steel, the composition of the concrete, and environmental conditions.

Carbonation in Concrete

Carbonation is the reaction of carbon dioxide from the atmosphere with calcium hydroxide in the concrete, forming calcium carbonate. This process reduces the alkalinity of the concrete, lowering the pH from around 12.5 to below 9.

A decrease in pH due to carbonation leads to the depassivation of the steel reinforcement. At a high pH, a protective oxide layer forms on the steel surface, but as the pH drops, this layer breaks down, making the steel vulnerable to corrosion.

Measuring the depth of carbonation involves using phenolphthalein indicator solution, which changes color in the presence of high pH levels. This test helps determine the extent to which carbonation has progressed within the concrete.

Interplay Between Chlorides and Carbonation

Chlorides and carbonation often act synergistically, exacerbating the corrosion process: carbonation lowers the pH, reducing the threshold for chloride-induced corrosion.

While both chlorides and carbonation individually contribute to corrosion, their combined effect is more detrimental. Comparative studies highlight that structures exposed to both factors deteriorate faster than those subjected to only one.

The Effects of Corrosion on Structural Integrity

Corrosion of the steel reinforcement results in a loss of cross-sectional area, reducing the load-bearing capacity of the structure. This can lead to failures under loads that the structure was originally designed to withstand.

In addition, as steel corrodes, it expands, creating tensile stresses within the concrete. These stresses lead to crack formation and propagation, further facilitating the ingress of aggressive agents like chlorides and carbon dioxide, perpetuating the cycle of deterioration. Indeed, the cracking of concrete is an effective early warning system that alerts us to the need for further investigation.

How to Assess the Condition of Reinforced Concrete Structures

There are various non-destructive that we use to assess RC structures to give us timely information as to their condition. These include:

  • Ground-penetrating radar (GPR)
  • Ultrasonic pulse velocity (UPV)
  • Half-cell potential measurements
  • Electrochemical methods, including linear polarization resistance (LPR)

Prevention and Mitigation Strategies

Preventing and mitigating corrosion in reinforced concrete structures is critical to ensuring their longevity and structural integrity. Therefore, it’s crucial to employ comprehensive strategies that address the detrimental effects of chlorides and carbonation to protect new construction and maintain existing structures. A multi-faceted approach encompassing three key strategies helps us to significantly reduce the incidence and impact of corrosion in RC structures:

1.    Material Selection

Selecting materials with higher resistance to corrosion, such as stainless steel or epoxy-coated reinforcement, can significantly mitigate the risk of corrosion in RC structures.

2.    Protective Coatings

Applying protective coatings to both concrete and reinforcement can provide a physical barrier against the ingress of chlorides and carbon dioxide, prolonging the service life of the structure.

3.    Cathodic Protection

Cathodic protection involves applying an external electrical current to the reinforcement, counteracting the electrochemical process of corrosion. This method is highly effective in halting the progression of corrosion.

4.    Innovative Monitoring Technologies

Innovative monitoring technologies, including sensors embedded within the concrete, provide real-time data on the condition of the reinforcement. These facilitate proactive maintenance and early intervention, reducing the long-term costs of corrosion management.

What is the Future for Reinforced Concrete Corrosion

Ongoing research in materials science and monitoring technologies promises to enhance our ability to combat corrosion in RC structures. Development of corrosion-resistant materials and real-time monitoring systems are areas that hold great potential for significant improvements.

By investing in these research areas and implementing robust maintenance and mitigation strategies, we can significantly extend the lifespan and safety of RC structures. It’s a proactive approach that not only improves the sustainability of our infrastructure, but also helps to reduce long-term repair and maintenance costs, and, most crucially, ensure public safety.

Final Thoughts

While the interplay between chlorides and carbonation presents a formidable challenge in the maintenance of reinforced concrete structures, continuous research innovation of technologies, effective monitoring, and improvements in preventative measures will help us to continually improve the mitigation of these factors in the corrosion of RC structures.

At the Institute of Corrosion, we’re committed to advance understanding and capability in this critical industry. We work for our members to deliver tangible progress in bot corrosion science and corrosion engineering. The benefits of becoming a member of the Institute don’t stop there.

We provide exceptional routes for networking, help you to increase your visibility in the industry, and offer unrivalled opportunities for professional development, as well as discounts on training courses, free downloads of EuroCorr papers in the Members Area of ICorr website, and much more.

Click here to learn more about the benefits of ICorr membership and how to become a member.