Structural concrete repair

Fix the concrete, then waterproof it.

Spall and delamination repair, corroded rebar treatment and overhead patching — the work that has to happen before any coating is worth installing.

Request a site assessment Call (236) 873-2580

The work

Corrosion is a volume problem.

Reinforcing steel in sound, alkaline concrete does not rust; the concrete passivates it. Once chlorides reach the steel, or carbonation drops the pH far enough, that protection is gone and the steel begins to corrode. Corrosion products occupy several times the volume of the original steel, and that expansion cracks the concrete from the inside out.

By the time you can see a spall, the damage extends further than the visible edge. We sound the surrounding area with a hammer or chain drag to find every delaminated zone, then saw-cut a square perimeter and remove to sound concrete behind the bar — not just to the face of it, which is the most common shortcut and the reason repairs fail at the edges.

The steel itself gets cleaned to bare metal and treated. Where section loss is significant it gets supplemented. Then the patch goes in with a repair mortar chosen to match the modulus of the parent concrete, because a patch that is much stiffer than what surrounds it simply relocates the crack.

Removal: To sound concrete behind bar
Rebar: Cleaned, treated, supplemented
Mortars: Mapei Quick Patch · Mapecrete
Then: Membrane or coating

Detail

Overhead and vertical repair is a different trade.

Parkade soffits and columns are where structural repair gets genuinely difficult. The material has to hang there without slumping and cure without shrinking away from the substrate, which rules out most general-purpose mortars.

This is also the work most likely to reveal that a problem is larger than it looked from below. Where we find section loss serious enough to affect capacity, we say so and recommend a structural engineer rather than patching over a question nobody has answered.

Questions we get

Straight answers.

Is a spall a structural problem?

Sometimes. A shallow spall in a slab with plenty of remaining cover is a durability problem you should fix before it becomes a structural one. Significant section loss in reinforcing steel, or spalling on a column or a soffit, is a question for a structural engineer, and we will tell you when we think you are in that territory.

Why does the repair have to be square-cut?

Feathered edges on a repair are thin, weak and unbonded, and they fail first. A saw-cut square perimeter at full depth gives the mortar a proper edge to bond against, which is why a repair done this way lasts and a smeared one does not.

Can you repair and waterproof in one visit?

Yes, and it is usually the cheaper way to do it, because the mobilisation, containment and phasing are shared. Repair mortars need their own cure time before a membrane goes on, so the sequence adds a few days rather than a second project.