Cutting a hole in thick concrete slab

1 Sep 2008
Reaction score
United Kingdom
Further to my earlier thread on digging a manhole, I have taken the advice onboard about finding an existing pipe to attach an access chamber to instead (definitely better than a 7-foot deep manhole!!!)

Currently investigating the route of the drain from an existing gulley. The gulley is surrounded by a concrete slab approx 7-8 inches thick (measured by drilling through it with a long SDS bit).

I have cut the outline with a 9" diamond disc to try and contain break-out but I'm stumped with breaking out the middle. I tried drilling a load of 20mm holes and chiselling out with an SDS scutch, but the concrete is bl**dy good stuff! It is possibly 91 years old, and has absolutely no spalling or cracks despite its age. It literally killed the abrasive-type grinder disc I tried at first. No rebar though.

So, I've come up with a few ideas on how to break out the middle without smashing everything else up:

1) Attack with a pick-axe
2) Attack with a sledgehammer
3) Rent a diamond chainsaw

Any ideas? :D

Is there some sort of wedge I can use? You know, drill a hole with SDS, place wedge in hole then batter with 14lb hammer until concrete splits/explodes?
Sponsored Links
Why are you mucking about with something as resilient as aged concrete - use an electric heavy duty breaker.
Sponsored Links

DIYnot Local

Staff member

If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

Select the supplier or trade you require, enter your location to begin your search.

Are you a trade or supplier? You can create your listing free at DIYnot Local