How to fix holes in alfresco slab with rebar?

[pmac23]

I built a deck on top of my alfresco area of our house slab last year. 

While attaching the frame to the deck there were a couple of holes which I believe the drill was stopped because I hit some rebar.

At the time I planned to fill the holes, however I forgot until after I had put the boards down.

I kept meaning to take the boards up and fill the holes. However have been overwhelmed with work and other jobs.

I am now worried about possible rust and damage to the slab.

Can you recommend a plan of action?

Regards,

Paul

[MitchellMc]

Welcome to the Bunnings Workshop community @pmac23. It's wonderful to have you join us, and many thanks for your question about concrete slabs.

The minute a concrete slab is poured, the rebar inside it begins to rust. This is actually expected, as moisture from the ground and atmosphere slowly seeps through the porous surface of the concrete, which acts a bit like a sponge. Even in slabs without any drilled holes, rebar will begin to corrode over time — though this is usually a very slow process and doesn’t pose a structural issue for many decades. So I wouldn't be overly concerned that you didn’t get a chance to fill those holes straight away. That said, if you’d like to seal them up now for peace of mind, you could remove the affected decking boards to gain access and use a product like Earl's 1kg Concremate Expanding Cement to fill the holes. Alternatively, you could squirt Sikaflex 11FC into them, which is easier to apply and still provides a good moisture barrier.

Please let me know if you have any questions.

Mitchell
 

[pmac23]

Thank Mitchell