making a hole through a concrete slab

[JohnD]

trying to pass new supply pipe from outside the house to come up under through the floor inside

have dug the trench but have hit hard and dense foundation. I hopefully imagined that we would be able to drill a 25mm hole diagonally through the room floor to emerge into the trench.

however, the concrete is so hard and dense that the drill I hired made neglible impact. The local builder helping me has made a hole through the concrete subfloor (which is not as hard as the foundation) and through the wall to meet it. However as this does not penetrate the foundation it is only just below ground level.

the foundation slab is at ground level and the concrete sub-floor is about 100mm on top of that.

he says a kango would make an enormous hole in the floor, and as he had imagined it would be a one-day job to run the new pipe he is getting a bit fed up and wants to get finished and away.

What suggestions please?

 

[Burnerman]

A diamond tipped core drill, maybe?
John

 

[JohnD]

sorry, should have added we tried that (32mm) as well as a 25mm TCT drill.

the diamond core got through the bricks but was very slow. It was ineffectual on the concrete. We used the small local hire shop and the SDS (or SDS+?) drill did not seem as big and heavy as the one I hired back in Hampshire last time I drilled a 105mm core.

I suggested SDS+ chisels to the builder but he did not seem impressed. I don't know if that was just because he's fed up.

We have to go about 600mm down and 600mm along; or diagonally maybe 750mm

 

[Burnerman]

I would say that you need a much heavier drill than the one you have hired at the moment.....I've gone through a concrete raft with one, but I used water to cool it - which I wasn't sure if I was meant to.
Failing that, I guess its a heavy Kango, and lots of patience....
John

 

[Andygasman2010]

Hire something like this http://www.makita-direct.co.uk/acatalog/Makita_HR5211C_52mm_SDS_Max_Rotary_Demolition_Hammer.html SDS or SDS plus will be too light duty, you'll need SDS max at the least

 

[JohnD]

so a demolition hammer is what I should be hiring? is that sort of thing readily available at a larger outlet?

 

[Andygasman2010]

Something like this http://www.hirestation.co.uk/product.php?productid=104 This is a medium 5.9kg but you can get up to about 11kg I think. Heavier the better. This is the bit you'll need too http://www.lawson-his.co.uk/scripts/details.php?cat=SDS-Max Hammer Drill Bits&product=54018 (scroll down to see the 35mm bits)

With them being mainly used for chiseling they're not built with clutches (i think!) so if the bit sticks it has a tendancy to break your wrist so be careful! When I use them I only keep one finger inside the handle to pull the trigger that way if it does bite it's less likely to do any harm.