Block Paving drive issues

[Fletch G]

Hi all,

 

 

Would really appreciate your honesty and expert advice I’m not a landscaper im a gas engineer who tried to save himself few grand during hard times by laying blocks myself 

 

 

Long story short as you can see in pictures I extended my block paving and decided to hire a guy with a digger who provided the sub base (road plannings you can see in the pictures)  and skip etc .

 

 

He arrived with road plannings  as he said the mot from quarry wasn’t great at the time during lockdown. He dug out and put in well over depth needed and it was gone over numerous times with the whacker plate 

 

 

Now where I park my van or car it sinks I’ve tried to put some extra sand under 10-20 block as a test but it sinks again and some bits are pretty severe 

 

 

I’ve had different opinions about running over it with a very heavy duty whacker and it may level itself out as it all slopes towards the road , some others saying lift blocks and sand and go over with actual mot whack it then re sand etc then others saying full take it all up and re do with mot type 1

 

 

Only thing is to hire someone would be 3-4K in being quoted and to do it myself would be £750 guy with digger and skip then mot then someone on day rate for at least 2 days so that’s expensive

 

 

Just really fed up with it and looking for some sound advice please 

 

 

Thanks in advance 

[joe90]

Like you I am not a landscaper but I don’t think a whacker is man enough for a vehicle parking space, I used a diesel vibrating roller on top of scalpings and my drive has not moved at all. It all depends on the soil below the scalpings, it really should have been dug out to something that had not been disturbed before, sub soil. Not sure of the cure but someone else will be along in a mo.

Edited July 4, 2022 by joe90

[ProDave]

If you are wackering it, you need to put it down in thin layers, run the wacker over several times then add a bit more, as @joe90 says a wacker may not be up to the job especially if he did it in thick layers or there is still soft sub soil underneath.

 

It might be worth just leaving it for now and seeing if it settles to a point where it stops sinking further, then lift, re sand and re lay the blocks.

[nod]

For how much is there 

I would take up the new and lay each one on a bed of mortar 

I did this at my sons 

He got his iddiot mate down to dig out and mot 

No where near deep enough 

It’s been down four years without any movement 

 

[saveasteading]

Much as the comments above.

 

Whacker over the surface is a waste of time.

 

Road planings are absolutely fine instead of sub-base, unless it is very fine stuff from footpath toppings. In fact it binds better than pure stone. The possible downside would be that rain doesn't get through and away, but  probably not the problem.

Road planings would not compact well though without care and attention due to the sticky surfaces, but would later under wheel loading.. 

 

The usual issue is lack of compaction. Digger drivers generally assume that driving over it with their tracks will compact it , but it won't. Neither will a whacker plate do much other than the very surface. Also most groundworkers put down too much thickness and the bottom remains uncompacted.

More explanation upon request.

 

2 options.

a proper job requires you to relay the sub-base in thin layers. 50mm suggested if a whacker plate, (rather than a vibrating plate which wont do much).

Then the sand bedding and blocks, using vibrating plate.*

OR at your own risk. remove the area of sunken blocks and relay sharp sand to the required higher level, perhaps with a bit of cement in it. There is a strong chance of more settlement esp as it is tricky to predict how much the new sand will compact.  But this would be f few mm.

Also be aware that blocks never go back in the same are and you will have to grind some edges off the last line to go back in.

 

Perhaps 20 years ago, the standard design for driveways was blocks on sub-base. But then they changed it to having a layer of concrete or tarmac beneath, as problems like yours were becoming common.

 

* £299 from Aldi plus compulsory delivery charge, and the same machine is at toolsation for £600+. nice profits there  But aldi wot deliver to Inverness, even though they have a store there.

[markocosic]

Sand is like water. It will move. If you put 10 mm everywhere then you get an even compression everywhere. If you put 5 mm in some places and 25 mm elsewhere you'll have a mess. Sub-base needs to be level.

 

Sub base needs to be laid in layers (say 50-75 mm thick; 100 is probably too much) and whacked. With a wacker big enough to settle it (200 kg diseasel jobbie) not the little wacker (70 kg petrol jobbie) that's just for "vibrating the blocks smooth/vibrating the sand between the blocks to lock them"

 

https://www.speedyservices.com/hire/building-site-works/18_0109-h-Wacker-Neuson-DPU3050HE-500mm-Reversible-Plate-Compactor-Diesel-206kg

 

Hard to fix without digging out the lot.

[Fletch G]

3 hours ago, markocosic said:

Sand is like water. It will move. If you put 10 mm everywhere then you get an even compression everywhere. If you put 5 mm in some places and 25 mm elsewhere you'll have a mess. Sub-base needs to be level.

 

Sub base needs to be laid in layers (say 50-75 mm thick; 100 is probably too much) and whacked. With a wacker big enough to settle it (200 kg diseasel jobbie) not the little wacker (70 kg petrol jobbie) that's just for "vibrating the blocks smooth/vibrating the sand between the blocks to lock them"

 

https://www.speedyservices.com/hire/building-site-works/18_0109-h-Wacker-Neuson-DPU3050HE-500mm-Reversible-Plate-Compactor-Diesel-206kg

 

Hard to fix without digging out the lot.

Thanks for reply mate what if I went over it with the big whacker plate you’ve shown and then put some mot over top and whacked that ? Would it work ? 

[Fletch G]

On 04/07/2022 at 17:07, saveasteading said:

Much as the comments above.

 

Whacker over the surface is a waste of time.

 

Road planings are absolutely fine instead of sub-base, unless it is very fine stuff from footpath toppings. In fact it binds better than pure stone. The possible downside would be that rain doesn't get through and away, but  probably not the problem.

Road planings would not compact well though without care and attention due to the sticky surfaces, but would later under wheel loading.. 

 

The usual issue is lack of compaction. Digger drivers generally assume that driving over it with their tracks will compact it , but it won't. Neither will a whacker plate do much other than the very surface. Also most groundworkers put down too much thickness and the bottom remains uncompacted.

More explanation upon request.

 

2 options.

a proper job requires you to relay the sub-base in thin layers. 50mm suggested if a whacker plate, (rather than a vibrating plate which wont do much).

Then the sand bedding and blocks, using vibrating plate.*

OR at your own risk. remove the area of sunken blocks and relay sharp sand to the required higher level, perhaps with a bit of cement in it. There is a strong chance of more settlement esp as it is tricky to predict how much the new sand will compact.  But this would be f few mm.

Also be aware that blocks never go back in the same are and you will have to grind some edges off the last line to go back in.

 

Perhaps 20 years ago, the standard design for driveways was blocks on sub-base. But then they changed it to having a layer of concrete or tarmac beneath, as problems like yours were becoming common.

 

* £299 from Aldi plus compulsory delivery charge, and the same machine is at toolsation for £600+. nice profits there  But aldi wot deliver to Inverness, even though they have a store there.

Thanks for this reply mate you obviously know your stuff 

 

what would you do if it was yours mate to lift it all and re do with mot hiring somebody with digger and skip etc will cost me prob £1000-£1500

 

to pay someone to do it will be between 2.5k-3.5k

 

You think if I got a real heavy duty whacker and then whacked it again and maybe bang some mot over top of that would that work maybe ?

 

it’s driving me insane can’t stand to look at it any longer

 

thanks 

[saveasteading]

It depends. If the sunken area is clearly caused by the weight of vehicles (half a ton on each wheel just on 3 or 4 blocks), then relaying that area would suffice. (A) 

But if the rest might be loaded at some stage then it will probably settle too.(B)

 

Sometimes lo-tech is best. Set aside the sunken blocks, lay up to bed level using sharp sand with a bit of cement. and compact it. Hire a vibrating plate for that, aiming for 30% or more discount on the list price.

OR buy a tamping bar for £30, and get some free exercise. The thump from the bar gives you the confidence that the ground now carries a significant load. Any softer areas will be identified.

Perhaps do the last 10mm in sharp sand loose, and keep it 2mm high, then the blocks can bed in.

This may undulate a bit or move again, but should be very minor.

You will need to grind off the nibs on the last blocks to go in.

B. Lift all the blocks, compact the sub-base with your thumper, and it will very likely go down noticeably as you do. Where it has already sunk it may stay firm as the vehicle has done the work already.

Check the level and bring it up to level with either sub-base (if thick) or sharp  sand with some cement if thin, and compact it.

Then, as you have a whole area, you can lay the blocks on the recommended depth of sharp sand, then vibrate the lot. Whether 20mm or more, the main thing is to allow for 10% settlement, and have the same thickness all over.

 

https://www.wickes.co.uk/Wickes-Steel-Professional-Contractors-Rammer---1-245m/p/186866