Holes with in holes!!

[John Thomson]

Hi,

I'm fitting some stainless steel posts into a 5m long ramp then down 3 steps. I have core drilled 9 x 65mm holes 400mm deep, however the majority of them have big holes inside the holes where the soft concrete/hard-core has broken away.

Any advice on what I could use to bung the holes up and stop the concrete from flowing away??

 

[Doggit]

You're going to need to fill the holes - ideally with concrete, otherwise you may not have enough lateral stability. If you feel the holes are okay, and won't affect the post going in, and if there is enough concrete in there to adhere the new concrete to, then you could consider using expanding foam, and then redrill the holes to remove the foam, but it'll get a bit ripped up. This is going to be a judgement call on your part as to how big the holes are.