I've used recycled tarmac on my 100spm drive ready to be block paved

[Willg]

Hi everyone, I am now on my second set of contractors for my drive as the first ones turned out to be clueless and I wasn't happy with the time it was taking or the advice.

 

I'm doing 100 sqm of block paved driveway - new guys have come in done a few days setting out but are now saying they aren't happy laying on top of 150 mil recycled tarmac, this is all I could get hold of a couple months ago following how wet it had been and it was recommended so I went with it, after looking into it it doesn't seem the best sub base and I'm not sure you can use it, would I be better off getting a digger back in scraping it back and adding a 50 mil type 1 layer on top? As it stands at the minute it's 90 mil from the required level and it's been whacked, blocks are 60 mil so I guess they were going to do a sand screed of 30 mil, can anyone advise me what's best to do I don't want to spend all this money and the drive sinks in 6 months.

[Nickfromwales]

Listen to the advice of the new contractors as they will then be liable for longevity etc. If you ignore them then you’d be blamed for any failures.

 

Short cuts take 3 times longer and are always 3 times the cost. Remove the U/S sub base and get it all replaced with type 1, and install ACO drains to manage storm water. 

[saveasteading]

Recycled tarmac is great as long as it is a coarse mix, and not only fine stuff from toppings and footpaths.

 

Many people don't realise that it is nearly all stone and sand, and the black stuff just glues it together. (5% or so if I recall)

If you ask the contractor why it is not acceptable it would be interesting to hear.

If well crushed, (not in big lumps) then well laid it can be better than type 1.

It's 150mm thick and you have presumably whacked it or rolled it. It will never get that load again. 

The problem i see  is with 30mm sand. 

That is very thick and will be affected by rain and weeds. Also, with block paving, you can get very local point loading. 30mm sand tends to suggest you need it to adjust to a good plane surface could you use less?

Test the surface by driving back and forward many times. Does it show any settlement?

Now jack up the car so you have half a ton on a small area. OK?

 

Worst case? If it ever settles locally then blocks can be reset.

 

I've even used it under a factory slab taking very large loads. No problem.

 

[Oz07]

Whats the specific issue with the planings?

[Redbeard]

Do the circumstances require it to be a permeable sub-base? If so I am not sure MOT will cut the mustard (others on here know more than I).  I used between 200 and 400 c40mm crushed limestone, membrane, and finer limestone (but not sand or MOT) as a bedding layer.

[saveasteading]

20 minutes ago, Redbeard said:

Do the circumstances require it to be a permeable sub-base?

@Redbeardis correct. Type 1 is designed to be as dense and stonelike as possible, and it follows on that it has low permeability. Crushed bitumen road is much the same mix with added bitumen so is even more so.

@Willg you haven't mentioned this and perhaps you have a slope in mind and somwhere for the water to go 

[Gus Potter]

Road planings can be a great material. 

 

But before you import this stuff onto your site you need to know where it came from. 

 

Beware of cheep offerings as they can be full of contamination. Just say the planings come from the old bus station.. you'll have brake fluid, gear box oil etc. Or from a busy road junction. Worse still from the road into an old scrap yard.. then you'll get heavy metals and all sorts. 

 

Contaminated road planings can be expensive to dispose of unless you have a gullable self builder looking for a cash deal! At the end of the day you are responsible for the site and what comes onto it.

 

Main roads are made up of several layers. The wearing top coat, higher bitimen content (the binder) . The wearing coat is often 40mm thick. Then the base course, larger aggregate (often 20mm - dust) with a lower binder content often 100mm thick and then the sub base which can vary (from memory between 150 and 300 mm thick) and contains 40mm aggregate down with a lower binder still. The base course is probably the best to get your hands on. 

 

6 hours ago, saveasteading said:

Many people don't realise that it is nearly all stone and sand, and the black stuff just glues it together. (5% or so if I recall)

Have a read at @saveasteading post above. 

 

 

[Willg]

5 hours ago, Oz07 said:

Whats the specific issue with the planings?

They've never worked with them and were saying when they drove off it after it has been whacked it showed movement I believe.