ᐅ Foundation slab – reinforcement visible from the side

Created on: 13 Oct 2019 17:29
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ecCurity
Hello everyone,

I have already gathered some information on this topic through this forum. Our foundation slab was poured last week. The formwork has now been removed, and I noticed the following:

1. At one spot (on the side), the reinforcement is visible (see picture). I am concerned that the concrete cover at the edge of the slab may generally be insufficient to protect the reinforcement from corrosion. Are there spacers used at the edge of a foundation slab to ensure the concrete cover? Before the concrete was poured, I didn’t see any spacers here (only the support strips on the construction foil). Should a concrete cover of 3–4 cm (1.2–1.6 inches) also be guaranteed at the edge? Could this be fixed by slightly increasing the size of the slab?

2. The foundation slab measures about 10 x 10 meters (33 x 33 feet). The structural calculations assume a slab thickness of 30 cm (12 inches). However, at one corner (approximately 3 meters (10 feet) long), the slab is only 23 cm (9 inches) thick. Before I take this issue to the structural engineer, I wanted to hear your opinions on whether this could possibly be remedied by adding concrete to fill the 7 cm (2.8 inches) difference?

Thank you in advance for your feedback.

Best regards


Rough concrete surface with diagonal crack; next to it lies a yellow measuring tape.
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danixf
27 Oct 2019 00:44
What kind of spacers? Can you explain that in more detail?
The architect’s suggestion sounds good.
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ecCurity
27 Oct 2019 00:49
To maintain a consistent gap at the edge area from the formwork (and thus to ensure the minimum concrete cover), the reinforcement should not be placed directly against the formwork. That would be problematic, wouldn’t it?
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Steven
28 Oct 2019 10:13
Hello ecCurity

The distance to the formwork is simply maintained by not placing the reinforcement directly against it. What else would spacers achieve in this case?
The architect's suggestion is good. The reinforcement must be protected against rust. It will be. It is iron. Rusting shouldn’t occur, but it’s also not a catastrophe.

Steven
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Silent010
28 Oct 2019 13:23
ecCurity schrieb:

We reviewed everything again with the structural engineer and recalculated. Fortunately, the thickness of the slab is sufficient.


Keep in mind that with the slab thickness reduced by almost 25%, you will also pay less for it. For example, with a slab measuring 10 x 10 meters (33 x 33 feet), a reduction of 7 cm (3 inches) means 7 cubic meters (about 247 cubic feet) less concrete.