concrete driveway

[slash381]

My concrete drive has a section approx 3m square which has cracked and sunk with a hole appearing where a bit has broken off, looking into the hole it appears there is a cavity underneath the area which is all cracked the rest of the drive way is fine. Could this be caused by subsidence? my idea is to cut out the cracked area put a 6 inch hardcore base down then replace with new concrete, my question is is it as simple as cutting out damaged area putting sub base down with a wacker and pouring new concrete in or am i missing something?

 

[r896neo]

no you are not but if the 'hole' is very noticible it may be worth investigating why it has sunk? If it has only sunk a bit then wack away.

Drill a few short lengths of rebar into the surrounding concrete all the way around and leave them protruding out 6 inches. This will catch the new section of concrete and help reduce the cracking at the join.

 

[noseall]

If the driveway has been constructed from a great deal of made up material then the void is likely to be a settlement issue often confused with subsidence.

 

[TicklyT]

Occasionally a leaking water supply or drain pipe can cause a section of a footpath or driveway to drop like that as the water washes away some of the material below the concrete without ever appearing on the surface. Once you have cleaned out the hole you should be able to see if that is the cause.

 

[slash381]

found the watermains and gas pipes with my pick luckily didn't do any harm,there appeared to be no reason for subsidence so have put new base in and filled with readymix, it cost £200 in total £40 for tool hire, £160 for concrete, got the sub base for free(road planings) and my brother took the soil away with his tractor and trailer for nowt too, very pleased with the outcome thanks for posts.