Bedding layer question for newbie

[moonbow]

hi guys great site,i have just ripped my drive up mainly 3x2 paving dug out 250mm from fpl getting the mot ordered after the weekend,my question to you guys is one contractor has told me to lay the blocks on mot dust or 6mm limestone to dust just wondered if anyone else uses this method,because when i left school i helped a block paver for 3 months doing big cul de sacs on building sites so i know the craig but we always used sharp grit sand so whats best i will get some before and after photos up soon as ive finished

[ken]

150mm type 1 mot. then lay the blocks on 35-50mm of washed grit sand

[moonbow]

150mm type 1 mot. then lay the blocks on 35-50mm of washed grit sand

cheers ken mate
thats what i thought but just wondered if it was a new tecnique

[ken]

Im not 100% up on permeable block paving, but I rec that laying method is what your contactor was advising you on.

[mickg]

6mm to dust or clean 6mm stone has been used in Europe for quite a few years, the advantage of using the 6mm stone rather than grit sand is you don't have any issues with the grit sand turning to slurry if its been raining so you can continue screeding and laying the block paving

[moonbow]

yeah i seen some yanks on youtube laying block paving on small stone looked a cracking neat job,i just wondered which was best cos i like my jobs to look and last 100% like anyone does

[Pablo]

Clean 6mm grit is very good for laying on timewise it's much quicker to rake out and screed and you can use it in all weathers. I screeded out about 50m2 of it today in readiness for some artificial grass it's so much lighter than sand to push about I'm planning on trying out my next small driveway with it as a tester with a veiw to converting to it the benefits seem worth a stab. It's not as readily available but I'm about to build 6 bays for loose materials like sand stone soils and bark that I use regularly the benefits of bulk buying will soon pay for it and I'll get an old tractor with a shovel to load it.

[Tony McC]

It depends on where you are. In some parts, good grit sand is a rare thing and so some contractors will use 6mm down, while in other areas, such as here in NW England, you can't bloody move for superb quality grit sand and so that has become the default bedding material.

The only real issue with 6mm down is the fines content. On commerical projects, or anywhere that there might be regular vehicle traffic, the fines content of the laying course is critical to its long term performance and you will find that engineers will reject some 6mm down material unless a sieve test shows it to comply with 7533:3. Most of the cheaper 6mm down is exactly what it says it is: anything from 6mm to infinitesimal dust in no fixed proportions. The stuff that complies with the D Tables in 7533:3 usually commands a premium price.

[jack101]

It depends on where you are. In some parts, good grit sand is a rare thing and so some contractors will use 6mm down, while in other areas, such as here in NW England, you can't bloody move for superb quality grit sand and so that has become the default bedding material.

The only real issue with 6mm down is the fines content. On commerical projects, or anywhere that there might be regular vehicle traffic, the fines content of the laying course is critical to its long term performance and you will find that engineers will reject some 6mm down material unless a sieve test shows it to comply with 7533:3. Most of the cheaper 6mm down is exactly what it says it is: anything from 6mm to infinitesimal dust in no fixed proportions. The stuff that complies with the D Tables in 7533:3 usually commands a premium price.

Can you elaborate on that point? are you saying that it should be 6mm single size or are you saying it should have fines in it? what is the reason for that?
i am considering using the 6mm size stone because we cant get good grit sand.

thanks

[jack101]

Clean 6mm grit is very good for laying on timewise it's much quicker to rake out and screed and you can use it in all weathers. I screeded out about 50m2 of it today in readiness for some artificial grass it's so much lighter than sand to push about I'm planning on trying out my next small driveway with it as a tester with a veiw to converting to it the benefits seem worth a stab. It's not as readily available but I'm about to build 6 bays for loose materials like sand stone soils and bark that I use regularly the benefits of bulk buying will soon pay for it and I'll get an old tractor with a shovel to load it.

how did you get on with your 6mm stone test? are you converted? any tips?
thanks

[Pablo]

not had a chance to try yet Jack been busy trying to finish all the gardens I couldn't get done over the winter.

[jack101]

any update here guys? anyone used 6mm single sized stone and prefer it ? just dont have good grit sand available.