Sub-base - Wackering

[HayDown]

Hello all
The garage, drains, etc have now been passed by the BO and my sub-base has been put down on my driveway, I am at the moment wackering, when will I know if I have wackered it enough? Can you wacker it too much!
Sub -base is type 1 stone
Would be grateful for any advise. Thank you

[IanMelb]

I've been told (and discovered) that the compactor plate will jump around like billy-o when there's no compaction left in whatever it's jumping on.

I'll let the experts confirm or refute that ...

[seanandruby]

compact to refusal thats when it jumps. you cant wacker to much, but you can wack needlessly.

[Tony McC]

You can't over-compact a sub-base, but it's quite difficult to achieve "compaction to refusal" using a typical plate compactor because most of those used by driveway contractors or supplied by hire shops are too lightweight. BS7533:3 requires a plate to have a minimum effective force of 1400kg/m². This is why I always recommend use of a roller for sub-base compaction.

[lutonlagerlout]

so in laymans terms is a 1 ton wacker ok for drives?
yay or nay?
LLL ???

[Rich H]

hmmm. Used a 1 ton for block paving before but it's a lot of passes to be sure it's compacted. On that gravel drive the MOT is 120-170mm deep (although generally no more than 150mm over 90%) and I knew the wacker wouldn't be enough so hired a roller instead.

[Tony McC]

A 1 tonne plate is fine: the problem is that most plates used in the residential paving trade are around 80-100kg and even with the centrifugal force, don't come anywhere near the required 1400kg/m² required for effective sub-base compaction. While they're absolutely fine for compaction of the laying course and final consolidation of the blocks, they just don't hack it with a sub-base.

[Rich H]

Sorry - thought you meant 1t/m2 rather than a 1t machine :p

[lutonlagerlout]

hmmm i was given to understand that our wacker= a bomag 450 mm wide ,had a 1 tonne wacking capacity
the plate itself weighs about 80kg,i can just about heave it on the back of the pick up on my own.
saying that i always make at least 4 passes over the area in as many different directions as is possible,and thats each for the sub-base,bedding layer and final compaction
we keep getting pikeys comng round trying to flog us those little weenie ones,but not interested.
LLL ???

[Rich H]

Is that the one with the fold down wheels? Bloody heavy bugger but I still can't get to the 'compaction to refusal' that Tony refers to with much more than about 120mm MOT.

[seanandruby]

then do 120 layers,

[Rich H]

silly sod