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The illustrated guideConcrete restoration, done at the cause.
Why South Florida concrete fails, how far the damage has really gone, and what a correct repair actually involves — with the diagrams to see it.
Concrete is strong in compression but weak in tension, so steel reinforcing bars carry the tension inside it. Healthy concrete is highly alkaline, and that alkalinity forms a microscopic passive layer that shields the steel from corroding. Two things destroy that shield:
- Chloride attack. Salt air, sea spray and wind-driven rain drive chloride ions into the concrete. Once they reach the steel in enough concentration, the passive layer breaks down and corrosion starts. This dominates on the coast.
- Carbonation. Carbon dioxide reacts with the concrete over decades, lowering its pH from the surface inward until the steel is no longer protected.
Corroding steel expands to several times its original volume. That expansion cracks the surrounding concrete, then delaminates it, then spalls it — and once the concrete is cracked, more chloride and water reach the steel, so the process accelerates. That's why a small repair today is far cheaper than the same area left for five years.
Catching it early — at cracking rather than spalling — is the difference between a coating program and a structural repair.
Sound
Alkaline concrete keeps the steel passive. No visible distress.
Cracking
Early corrosion; hairline cracks trace the bar toward the surface.
Delamination
A hidden crack plane forms above the bar; concrete sounds hollow.
Spalling
Cover breaks away, exposing rusted, section-losing steel.
The single biggest reason repairs fail is skipping the investigation. Visible spalls are only where the concrete has already given up — active corrosion extends well beyond them. We map the true extent before writing a scope:
- Sounding / chain-drag to find delaminated concrete that still looks intact.
- Half-cell potential mapping to locate active corrosion you can't yet see.
- Chloride profiling & carbonation depth to measure how contaminated the concrete is.
- Cover meter / rebar scanning to check depth of cover and bar layout.
- Cores & petrographic analysis for strength and material condition.
The result is a repair-quantity estimate grounded in evidence — not a guess that balloons mid-project.
Every durable structural repair follows the same five moves. We specify each one and inspect it in place; the contractor performs it. Skip step three and the new concrete simply becomes the next thing to spall — exactly the kind of thing an owner's engineer is there to catch.
Remove unsound concrete
Saw-cut a squared-off perimeter — never a feathered edge — and chip back past the corroded bar to sound material.
Clean the steel
Abrasive-clean the reinforcement to bright metal; add or replace bar that lost section.
Protect the steel
Clean the bar to bright metal and apply the specified protective coating before any concrete goes back.
Rebuild the section
Form it and pour structural concrete back into the squared-off section — consolidated to fully encase the bar, restoring load-bearing capacity, then properly cured.
Waterproof & coat
Reinstate coatings, sealers and joint sealant to keep chloride and water out.
A structural member can only be repaired with structural concrete. The deteriorated area is saw-cut to a squared-off section, removed in full, and poured back — which is what restores the member's load-bearing capacity. We do not specify shotcrete, gunite, dry-pack or hand-placed repair mortar for a structural section: those materials produce a surface, not a structure, and they are not what we are prepared to seal.
Three moves, each one held open for inspection before the next begins.
1 Demolish
As directed by the engineer: saw-cut a squared-off perimeter — no feathered edges — then remove all unsound and chloride-contaminated concrete within it and chase the deteriorated steel back to sound bar. Repairs fail when the demolition stops short, so the limits are set by the engineer, not by the crew, and the opened section is inspected before anything goes back.
2 Prepare
Clean the exposed steel to bright metal. Add supplemental reinforcing where section loss requires it, lapped and developed to our detail. Coat the steel with the specified protective coating. Then set the formwork — tight, braced and ready to take a full-depth pour.
3 Rebuild
Pour structural concrete back into the squared-off section, consolidated so it fully encases the bar with no voids behind it — restoring the load-bearing capacity of the member, not merely its appearance. Then cure it properly: curing is the step most often shortened on site and the one that most determines whether the repair lasts. It is inspected, and it is not negotiable.
Real project photography — the most persuasive proof a board can see.
Cathodic protection is an electrochemical system, and it only works where there is a continuous electrolyte — that is, concrete that stays wet. In a permanently submerged or saturated element (a foundation below the water table, a seawall, a marine pile, a below-grade wall in wet soil) the concrete carries current reliably and a galvanic (sacrificial) anode system can genuinely arrest corrosion.
In the dry, above-grade concrete that makes up most of a South Florida condominium — balconies, walkways, columns, beams, slab edges — it does not. The concrete is not continuously wet, resistivity is high, the current cannot distribute, and embedded anodes are largely inert. They are frequently sold as a routine add-on to repair proposals. On a dry above-grade element, that is money spent for very little protection.
Our position is simple: we specify cathodic protection only where the element is genuinely submerged or permanently saturated and testing supports it. Everywhere else, durability comes from removing all the chloride-contaminated concrete, properly preparing and coating the steel, and rebuilding the section correctly — not from a product bolted onto a repair.
Balcony edges and elevated walkways are where South Florida buildings fail first: they're horizontal, exposed on multiple sides, and their traffic coatings wear out. Restoration typically combines edge and soffit concrete repair, replacement or re-anchoring of railing posts (a frequent hidden spalling source), new waterproof traffic coating, and corrected drainage so water stops ponding against the slab edge. Because balconies are life-safety elements, they get particular attention in Milestone inspections.
Post-tensioned slabs carry load through high-strength tendons under tension. Corrosion of a tendon or its anchorage is far more serious than ordinary rebar corrosion and demands specialized investigation before any repair — you cannot simply chip into a PT slab. Where a structure is post-tensioned, diagnosis includes tendon location and condition assessment, and repairs are engineered to maintain the load path throughout.
Keeping chloride and water out is half of durability. A restoration program specifies the right system for each surface: elastomeric wall coatings that bridge hairline cracks, traffic-bearing membranes for walking surfaces, penetrating sealers for exposed concrete, and flexible sealants for joints and cracks. These are consumables with 5–15 year lives, so we also set a renewal schedule the reserve study can fund.
Both destroy the steel's passive layer, but they behave differently. Chloride corrosion is localized and pitting — deep, concentrated section loss — and dominates near the coast. Carbonation is uniform, advancing as a front from the surface, and matters more on older or inland structures. Testing distinguishes them (chloride profiling vs. a phenolphthalein carbonation test), which changes the repair strategy and the choice of protective system.
Concrete condition is the heart of a Milestone inspection and a major line item in a Structural Integrity Reserve Study. Findings from a condition assessment feed directly into both. Under HB 913, an association whose Milestone inspection is due on or before 31 December 2026 may complete its SIRS at the same time as that inspection, and an association that has completed a required Milestone inspection may delay its SIRS for up to two budget years to prioritise the repairs the inspection identified. Coordinating the assessment and the reports under one engineer is how you avoid paying twice and getting two disconnected answers. See the compliance guide for how the requirements fit together.
Find out what's actually wrong with your concrete.
Condition assessment, testing and a sealed repair scope — from the engineers who specify and inspect the work, and do not bid it.
Request a condition assessment →