Locate the Threat Before the Structure Fails
Concrete Corrosion Surveys : When concrete begins to crack, delaminate, or spall, the structural damage is already in its advanced stages. The true threat lies deeper. Embedded steel reinforcement (rebar) is the backbone of your asset’s tensile strength, but when the chemical environment inside the concrete changes, that steel begins to corrode, expand, and physically tear the structure apart from the inside out.
The High Cost of Reactive Maintenance
Treating the visible symptoms of concrete degradation is a dangerous and expensive cycle. If you simply break out the spalled concrete and apply a patch repair without understanding the underlying chemical pathology, you are guaranteeing future failure. This creates the “incipient anode effect”—where the patched area is protected, but the corrosion is rapidly accelerated in the immediately adjacent, un-repaired concrete.
Whether dealing with marine infrastructure exposed to saltwater, highway bridges subjected to de-icing salts, or aging commercial buildings suffering from atmospheric carbonation, guessing the extent of the corrosion compromises safety and wastes maintenance budgets. To engineer a permanent solution, you must know exactly where the steel is actively rusting, how fast it is corroding, and why the concrete matrix failed to protect it.
Mapping the Electrochemical Reality
Structural Repairs treats corrosion as an electrochemical problem requiring an empirical, data-driven diagnosis. We deploy advanced surveying techniques to map the internal health of your asset, providing a comprehensive diagnostic report that dictates the exact remediation strategy required—whether that is targeted patch repair, galvanic anodes, or fully impressed current cathodic protection.
- Electrochemical Mapping: We utilize Half-Cell Potential testing to create a topographical map of active corrosion across the entire structure. This allows us to identify steel that is actively rusting right now, even if the concrete surface above it appears perfectly sound.
- Chemical Profiling: Our technicians conduct targeted depth-drilling to extract dust samples. These are tested for chloride ion concentrations and carbonation depth, allowing us to pinpoint exactly how far the aggressive elements have penetrated toward the reinforcement layer.
- Cover Meter Surveys: We map the depth of the concrete cover protecting the rebar, identifying vulnerable areas where the steel was placed too close to the surface during the original construction phase.
Corrosion Survey Technical FAQ
When concrete is poured, its high alkalinity naturally creates a “passivating” oxide layer around the steel rebar, protecting it from rust. However, over time, carbon dioxide from the atmosphere (carbonation) or chlorides (from seawater or de-icing salts) penetrate the pores of the concrete. This destroys the alkaline protection, allowing moisture and oxygen to trigger active corrosion.
Because corrosion is an electrochemical process, it generates tiny electrical voltages. A Half-Cell Potential survey uses a specialized reference electrode (often copper/copper sulphate) connected to a voltmeter and the rebar network. By sweeping this electrode across the concrete surface, we can measure these micro-voltages and map the exact locations where active corrosion is taking place beneath the surface.
Patching only addresses the symptom. If the surrounding concrete is still contaminated with chlorides or carbonation, it remains highly corrosive. Patching a single spot often shifts the electrochemical reaction to the surrounding steel, causing new spalls to erupt right next to your fresh repair within months. A survey tells us if we need to install sacrificial anodes alongside the patch to prevent this.
We apply a phenolphthalein indicator solution to a freshly exposed concrete core or drilled surface. The solution turns bright pink if the concrete is still highly alkaline (healthy) and remains colourless if the concrete has carbonated. Measuring the depth of the colourless zone tells us exactly how close the carbonation front is to the steel reinforcement.
