Cathodic Protection Design for Steel in Concrete Structures

Module D7 – Corrosion Deterioration and Energy Requirements

Welcome to Module D7 of the Cathodic Protection Design for Concrete Structures training course.

Even the most advanced power supply or high-grade anode material will fail if the underlying deterioration mechanisms and corresponding energy requirements are not accurately calculated. To stop active rust or prevent future deterioration permanently, a cathodic protection (CP) engineer must understand how carbonation and chloride contamination break down the natural passive state of embedded steel.

Whether you are safeguarding a structure suffering from general carbonation corrosion or localised chloride pitting, successful electrochemical design always comes down to navigating these foundational rules and environmental impacts:

  • Concrete Pore Chemistry: Realising that uncontaminated cement hydration naturally yields a high pH (12.5 to 13.5) to form a protective, passive oxide film on the steel.


  • Carbonation Ingress: Tracking how atmospheric carbon dioxide reduces the concrete pore water pH below 9, destabilising the passive layer and triggering uniform general corrosion.


  • Chloride Contamination: Evaluating aggressive chloride migration from seawater or road salts that initiates severe, localised pitting corrosion once a critical threshold is crossed.


  • Oxygen Availability Constraints: Anticipating whether abundant oxygen will cause expansive, spalling concrete failures, or if low-oxygen water-saturated zones will mask active section loss behind hidden, non-expansive rust staining.


  • Targeted Energy Requirements: Determining the precise cathode design current density dictated by BS EN ISO 12696, which allocates specific ranges for cathodic prevention on passive steel and for cathodic protection to stop active corrosion.

What You Will Learn

  • Natural Steel Passivity: Form stable defensive oxide layers via concrete pore water pH between 12.5 and 13.5.


  • Carbonation Decay Fronts: Track atmospheric CO2 neutralising concrete hydroxides to drop pH below 9 and trigger general corrosion.


  • General Corrosion Profiling: Analyse structural damage indicators, uniform metal section loss, and tapered rebar degradation due to carbonation.


  • Chloride Pitting Dynamics: Identify aggressive localised pitting from seawater or road salt without changing bulk concrete pH.


  • Oxygen-Rich Failure Risks: Observe oxygen access forcing expansive rust growth, driving concrete cracking, spalling, and compressive loss.


  • Oxygen-Starved Saturated Degradation: Detect non-expansive soluble rust products causing silent surface staining and tensile loss without cracking.


  • Advanced Field Diagnostics: Deploy half-cell potential mapping and exploratory physical breakouts when standard acoustic hammer surveys fail.


  • ISO Cathodic Prevention Metrics: Apply BS EN ISO 12696 target current densities of 0.2–2 mA/m² to safeguard non-corroding passive steel.


  • ISO Cathodic Protection Targets: Deliver BS EN ISO 12696 current densities of 2–20 mA/m² to arrest active pitting and general corrosion.


  • Global Compliance Alignment: Build your electrochemical engineering design schematics around foundational BS EN ISO 12696 standard frameworks.

Who This Course Is For

  • Junior Engineers & Techs: Grasp how concrete pore water pH (12.5–13.5) and chloride thresholds control steel passivity.


  • Project Leads & Managers: Evaluate whether structural decay demands low-output galvanic systems or high-capacity ICCP networks.


  • Design Consultants & Specialists: Calculate precise BS EN ISO 12696 target current densities based on active or passive steel states.


  • Asset Managers & Owners: Discover why invisible, oxygen-starved corrosion requires advanced half-cell mapping instead of acoustic hammer surveys.

Course Delivery & Requirements

To maintain strict compliance and ensure professional-level mastery, this course utilises an integrated learning framework:

  • On-Demand Video Lessons: High-yield visual walkthroughs covering carbonation fronts, chloride pitting, and oxygen-starved concrete diagnostics. Learn to select mandatory BS EN ISO 12696 current density parameters—ranging from 0.2–2 mA/m² for cathodic prevention up to 2–20 mA/m² for active cathodic protection.


  • Comprehensive Downloads: Complete access to downloadable slides (PDF) and the module overview (PDF) for offline reference.


  • Direct Expert Q&A: Submit technical questions directly through the online learning platform to John Paul Segers (MSc, CEng, FICorr, FIMMM, BS EN ISO 15257 Level 5 Cathodic Protection Expert).


  • Progression Gate: Learners must complete all video lessons, review all documentation, and pass the integrated assessment before unlocking subsequent modules.


  • 100% Mastery Criteria: Achieving a perfect score of 100% on the final 7-question module quiz is required to proceed.


  • Members have access to the On-Demand Video Lessons and Quiz for 1 year from the date of registration, and complete access to downloadable slides (PDF) and the module overview (PDF) for offline reference.

Course Structure and Content

This element of the course has been extracted from the complete Fundamentals of Design for Cathodic Protection of Steel in Concrete Structures course as follows:

    1. Welcome and Course Overview - Video

    2. Purchasing Cathodic Protection Standards - Video

    1. Module D7 - Corrosion Deterioration and Energy Requirements - Overview

    2. Module D7 - Corrosion Deterioration and Energy Requirements - Video

    3. Module D7 - Corrosion Deterioration and Energy Requirements - Slides

    4. Module D7 - Corrosion Deterioration and Energy Requirements - Quiz

About this course

  • £95.00
  • 6 lessons
  • 0.5 hours of video content

Module D7 - Learning Outcomes

At the end of this module, you will have developed an understanding of :

  • Identifying the state of the steel in uncontaminated concrete.
  • Identifying the causes and issues of corrosion and concrete deterioration.
  • Carbonation-induced corrosion. 
  • Chloride-induced corrosion.
  • Effects of corrosion in concrete with access to oxygen.
  • Effects of corrosion in concrete with limited access to oxygen.
  • Impact of corrosion on cathodic protection design.
  • Introduction to cathodic protection design current densities based on the state of the steel.
  • Identifying design current densities for cathodic prevention.
  • Identifying design current densities for cathodic protection.
  • Design current density - summary.


Module Quiz

At the end of this module, there is a quiz consisting of 7 questions that are aimed at reinforcing the learning and knowledge you have gained from attending this module. 

Frequently Asked Questions (FAQ)

  • How does atmospheric carbon dioxide initiate general corrosion in reinforced concrete?

    Atmospheric carbon dioxide (CO2) migrates through the concrete cover layer to react with free hydroxides (OH-) in the pore water. This neutralisation reaction lowers the concrete's naturally high alkalinity. Once the local pore water environment drops below pH 9, the protective passive oxide film destabilises and breaks down, triggering uniform general corrosion across the reinforcement.

  • Why is a standard acoustic hammer survey completely ineffective for water-saturated structures?

    Saturated concrete lacks adequate oxygen access, forcing active chloride-induced corrosion products to remain non-expansive. Instead of swelling and cracking the concrete cover, these soluble byproducts silently leach out to cause surface rust staining. Because a hammer survey only identifies physical hollows or delaminations, it will mistakenly register the concrete as sound, requiring engineers to deploy half-cell potential mapping and exploratory physical breakouts instead.

  • What determines whether a galvanic or an impressed current cathodic protection system is required?

    The choice is governed by the structural concrete's initial cathodic protection current demand, which represents the energy needed to arrest active corrosion. Galvanic systems generate lower, self-powered driving voltages suited for localised, lower-demand, or cathodic prevention applications. Conversely, Impressed Current Cathodic Protection (ICCP) systems utilise an external DC power source to deliver the much higher, adjustable current output capacities necessary to stop severe general and pitting corrosion.

  • What are the exact current density design ranges specified by international standards?

    Design parameters depend entirely on whether the embedded steel reinforcement is currently passive or actively corroding. For non-corroding steel, cathodic prevention is specified with a target current density between 0.2 mA/m² and 2 mA/m² of steel surface area. For actively corroding rebar, cathodic protection is mandated with an elevated range between 2 mA/m² and 20 mA/m² of steel surface area, complying directly with BS EN ISO 12696 parameters.

  • Does chloride contamination alter the bulk pH of concrete to initiate corrosion?

    No. Unlike carbonation-induced corrosion, chloride contamination via marine spray, road salts, or contaminated aggregates causes no change to the bulk concrete pH. Instead, once chloride ions migrate through the uncracked cover concrete and exceed a critical threshold of 0.3–0.4 wt% by mass of cement at the steel surface, they attack and destroy the protective oxide layer locally, triggering aggressive localised pitting corrosion.

  • What core factors must a designer evaluate when calculating a structure's energy requirements?

    A cathodic protection designer must evaluate the active or passive electrochemical state of the steel, the minimum current demand needed to stop ongoing rust, potential risks of future contamination post-installation, and the overall volume of physical concrete repairs required prior to system integration. These combined parameters systematically dictate the type of cathodic protection selected (galvanic or ICCP).

Module D7 - Corrosion Deterioration and Energy Requirements

Module D7 is the eighth of ten modules which form the complete Fundamentals of Design for Cathodic Protection of Steel in Concrete Structures course.

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Continue with your Learning and Personal Development

Individual modules do NOT provide CPD hours. To unlock your 50-Hour Certified CPD Certificate, you must complete all 10 modules.

Module D7 is the eighth of ten modules which form the complete Fundamentals of Design for Cathodic Protection of Steel in Concrete Structures course.

Completion of all modules of the full Fundamentals of Design for Cathodic Protection of Steel in Concrete Structures course provides you with a Continued Professional Development (CPD) completion certificate worth 50 hours.

I encourage you to continue with your learning and personal development to help identify that corrosion management can be used as an effective tool to support sustainable and low-carbon development now and in the future.