Concrete Durability: Chloride-Induced Corrosion in Marine Areas

Durability Performance of Reinforced Concrete in Aggressive Environments

Chloride-Induced Corrosion in Marine Infrastructure

Reinforced concrete (RC) is widely used in coastal and marine infrastructure

Chloride ions penetrate concrete cover → corrosion of reinforcing steel

Results: Cracking, spalling, loss of bond, reduced structural capacity

Introduction to the Topic

Why This Matters: Significance of the Problem

Slide 1 – Introduction (continued)

Overview

Reinforced concrete (RC) widely used in coastal and marine infrastructure due to strength, durability, and versatility.

In marine environments, chloride ions from seawater penetrate the concrete cover and initiate corrosion of reinforcing steel.

Cracking and spalling of concrete

Loss of bond between steel and concrete

Reduction in structural capacity and service life

Significance

Chloride-induced corrosion is the primary cause of deterioration in marine RC structures.

Understanding deterioration mechanisms is essential for:

Accurate service life prediction

Improved durability design

Sustainable infrastructure management

Literature Review: Triangulated Summary Table

Slide 3 – State of the Literature

Pang Long, 2016, Service life prediction of RC structures in marine environment using long term chloride ingress data: Comparison between exposure trials and real structure surveys

Quantitative

17 wharf structures

Variables include chloride content, chloride diffusion coefficient, concrete mixtures, period of exposures

Decrease in chloride diffusion coefficient over time, with blast furnace slag concrete mixtures, they have a significantly lower failure probability than OPC concrete.

1–8

Castañeda-Valdés Abel, 2023, The service life of reinforced concrete structures in an extremely aggressive coastal city. Influence of concrete quality

Quantitative

6 reinforced concrete specimens

Time to corrosion initiation, time to corrosion with induced cracking, electrochemical corrosion rate, time of exposure, w/c ratio, service life

Regression model (R² ≈ 91%) for corrosion prediction; corrosion rates increased significantly with higher w/c ratios and lower cover thickness, leading to drastic reductions in service life.

1–14

Kušter Marić Marija, 2020, Reinforced concrete bridge exposed to extreme maritime environmental conditions and mechanical damage: Measurements and numerical simulation

Mixed

1 case study, 21 samples

Chloride content, micro-climate parameters (wind direction & speed), depth of chloride, crack widths, depassivation time

• Chloride diffusivity increases significantly in cracked concrete<br><br>• Critical chloride threshold reached much faster in cracked vs uncracked concrete

1–11

Literature Review: Source Verification

Table A – Study Design, Key Measures & Effect Sizes

Source Table 1

Triangulated summary: study design, sample size, key measures, and reported effect sizes

Table B – Main Findings, Limitations & Contradictions

Source Table 2

Triangulated summary: main findings, reported limitations, and identified contradictions

Slide 4 – Screenshots to Verify the Triangulated Summary Table

Screenshots used to verify and cross-reference the information presented in the Triangulated Summary Table (Slide 3)

Identified Research Gap / Problem

Slide 5 – Research Gap

Research Problem

Reinforced concrete structures in marine environments deteriorate due to chloride-induced corrosion of reinforcing steel.

Key Issue in Literature

Existing studies focus on individual factors:

Chloride ingress and modelling accuracy

Material properties (e.g., concrete quality)

Structural damage (e.g., cracking, loading)

Identified Gap

Lack of an integrated understanding of:

Long-term marine exposure

Chloride ingress progression

Combined effects of mechanical damage and environmental conditions

Additional Issue

Inconsistencies between predictive models and real-world observations create uncertainty in service life predictions

Slide 6 – Research Question

Main Research Question

How does long-term exposure to marine environments influence the service life of reinforced concrete structures through chloride-induced corrosion of reinforcing steel?

How This Addresses the Gap

Integrates:

Environmental exposure (marine conditions, microclimate)

Material behaviour (concrete quality, permeability)

Structural factors (cracking, mechanical damage)

Moves beyond isolated analysis to a multi-factor approach

Expected Contribution

Improved understanding of corrosion progression over time

More accurate service life prediction models

Better design and maintenance strategies for marine infrastructure