Block paving moving and dipping - Block paving moving

[maxine788]

Hi all,

wanted to get some advice on recent block drive that was installed at my property 6 months ago using Marshalls tetrad blocks. Builder who laid the drive seems to have dug up the old tarmac drive and laid the blocks correctly although took him 6 months to complete from November 2018 to January 2019. The builder then used a compaction machine to set the blocks into the foundation (aggregate and sand, sand depths looked ok) The builder informed us that the drive was ok to drive on until he could get back to fill the joints with sand. This was 6 months ago and he has not come back to fill joints and re compact. Subsequently the blocks have started too move so that there are areas where the car tyres have driven over where the surface has dropped and areas where the car tyres havn't driven over where blocks now have 6- 7 mm gaps and are loose/rocking.
I am really looking for advice on how to go forward and resolve the issue

[MikeG]

That doesn’t sound great.
I suspect a lack of total compaction of the load baring base has resulted in the sinking of the blocks under the wheel track, this then effectively ‘makes space’ for the joints to widen in other places. As well as lack of full compaction it could be insufficient depth of load baring base which would also cause the fail.

The fact that the contractor didn’t even finish the job is a bit concerning ! The final addition of jointing sand does help to lock the blocks but they shouldn’t fail with out it.
The final compaction when the blocks are down should only really cause a level reduction of probably no more than 5mm.

Going forward it might be worth checking the depths of the load bearing subbase (crushed stone). You want at least 100mm depth.

[Tony McC]

Nothing, not a thing, sounds right about that installation.

My cowboy alarm is ringing like buggery!