ᐅ Reinforcement of concrete curb cut through

Hey everyone,

I have the following "problem." I have a concrete ceiling that extends over the terrace from the house. The original plan was to install a flat roof on the canopy. For this, the emergency overflows, gutter cutouts, and openings for connections to the water channel were made.

However, for aesthetic reasons, we decided instead to use a metal roof. Because of this, the overflows and openings are no longer necessary.

My roofing company has now filled the emergency overflows and openings with Styrofoam insulation boards and foam so that the surface can be plastered.

However, no one considered the cut reinforcement bars. Since this area was exposed and got wet over several weeks, the reinforcement at the cut edges has naturally started to rust.

Should this have been sealed somehow, or will it not continue to rust? My structural engineer says nothing will happen. It will just rust slightly on the surface and then stop.

Although water can no longer reach this area directly, there might still be some humidity, as I don’t think the foam is fully airtight.

I hope you can help me with this.

I have considered cutting out the Styrofoam again, then removing some of the rust from the reinforcement at the cut edges with a wire brush, and finally applying some cement to seal it airtight. What do you think about this?

Best regards,
Chris

Hello.

The Styrodur insulation actually needs to be removed, and the holes must be filled with concrete to restore the required concrete cover. However, you don’t need to treat the steel; that would not help at all because you only have access to the cut surface. Corrosion protection is achieved by isolating the steel from atmospheric oxygen and maintaining the alkaline environment within the concrete.

If the steel rusts, it expands and causes the concrete to crack and spall. This way, corrosion progresses through the entire structure.

Okay, first of all, thanks for the response.

The problem is that the roof is already in place. Because of that, I unfortunately can’t install any formwork inside to pour concrete. Does the concrete cover also have to be maintained if no water will reach that area?

To explain: I covered what was planned as a flat roof with insulation wool. A wooden structure would be attached to the upstand, and a metal roof would be mounted on top.

Best regards, Chris

19Chris84 schrieb:
Does the concrete cover requirement still apply if no water gets there?

Yes. It has little to do with water. Humidity (and air) is enough. Keyword: carbonation.

Okay, great, thanks. Would you then drill a few holes and insert rebar so that it bonds well during the concrete pour?

What would be suitable for this? Cement, mortar...?

Best regards, Chris

What I would like to know is this: Does carbonation always occur? From what I have read online, it happens with reinforced concrete in all cases unless the concrete is sealed with special coatings.

Thanks in advance

Best regards, Chris