I have a driveway that needs a new surface. I am planning on using crushed limestone aggregate (inch-and-a-quarter to dust, as they call it around here). Once the existing loose gravel has been removed, the substrate will be very firm and solid, cosisting of compacted clay and limestone dust.
The drive measures 25 mtrs x 3mtrs. Can anyone suggest how many tons of the said aggregate I would need, and how thick it should be before compacting?
I've heard of people putting down a membrane of some kind before spreading the aggregate? Is this necessary, and why?
I'm on clay here and about 20 tonnes did a similar area.
It takes a long time and many heavy lorries to compact down.
Having done so, grass will grow, whether or not you membrane it. In fact its likely to puncture any membrane anyway.
You should get about 4" depth which is enough IME for a 30 tonner. As long as you don't put a hard surface over..
Experience is that this surface will compact and wear to a dusty limestone track where the wheels go and grass everywhere else. It will be pragmatic free draining and stable for vehicles.
If you want it to look pretty another 20 tonnes of gravel will sort it.
4" is too thick above a membrane, it will let weeds get established. Also it sounds like MOT type 1, this will not free drain (well not very well) and may well require planning permission these days as they want to control the speed of run off.
I would use 10 mm crushed stone of some nice colour. I like Cotswold stone myself. Being jagged it doesn't move around like the pea gravel so many use. Its also coarse enough to stop weeds getting established.
Really? Type 1 is full of fines and doesn't have much in the way of voids for water to drain through. I think you will find it gets churned up like mud when its wet and you drive over it. Didn't you say it did in an earlier post?
Crushed stone will compact quite well without the fines, gravel, as in pebbles, will not settle, ever.
IME, Type 1 drains but slowly (much depends on the soil under it). But it can puddle in a heavy downpour. Crushed stone often tends to just crush more under traffic and ends up with fines as well and hence tends to act rather like type 1. Again the amount it crushes depends on what sort of stone it is, but most sedimentary stuff wears down somewhat in a few years. Granite may fare better.
Dennis is quite right. When an all-in-ballast (especially a material conforming to the grading requirements of DTp specified Type 1) is properly compacted, it is more or less impervious / impermeable. Provided, of course, the material is neither too wet nor too dry when it is laid / compacted.
Dennis is also correct about the planning permission
"The mixture of solids and fines is designed to ensure that there are no voids in the sub-base material once compacted, that the aggregate forms an acceptable level of interlock between the angular particles, and that the compacted sub-base will allow any ground water to drain through".
I had a "driveway" 3/4 mile long. I tried lots of different stuff over the years. All the ballast materials are a mixture designed to bind together when wet and with traffic. When new they go down like concrete. They are useless on gradients, ofmore than 20:1, the rain washes out the fine material and the bigger stuff then starts to move around under wheeled traffic. The varoius sheets to go under are only of limited use in my experience. They are nothing to do with weed control,they are supposed to reduce the thicknessof aggregate needed, indeed they are woven and completely free draining. Almost invariably soft spots allow sinking at some point whch have to be topped up. The rsulting puddles soften the subsoil and the process accelarates. "Tramlines" soon appear, it's bestif you make the roadwide enough so that you can vary your path to minimise the effect.
The stuff soon looks crap round a house. Weeds grow. Potholes form. Some potholes can be filled up with aggregate, others have to be dug out and bigger stone put in. The crap gets trailed into the house from this sort of road too.
On clay you need plenty of stuff, when soft, the aggragate just pushes in and the clay oozes up tp the surface. I would say you need to dig out 8"-9" and put in a layer of 2" stone and top off with ballast. Especially true on flat ground where the water jusr pools.
You need to make a definate provision to get rid of surface water, if it pools the clay is softened and the road will sink into it. "Sealed" roads such as tarmac prevent this and the base remains hard.
"harryagain" wrote in news:j1nvcm$had$ snipped-for-privacy@dont-email.me:
Some great info and advice here. That's a good point about how crushed limestone trails into the house via footwear. I am sorry to hear you guys say that weeds would still appear. The end of constant weeding was one of my main justifications for the expense...
I wish I liked the look of tarmac, because it's cheap and solves a lot of problems - but I don't. Brick paving would be way too expensive for my pocket. I guess that covers all the inexpensive options, doesn't it?
Tarmac does not solve the problem of weeds, and it comes with its own raft of problems. Cheap tarmac jobs last about five minutes.
We were banned from using tarmac or block by our ever-wonderful local planning office. Fortunately at the time we were permitted to demolish what had been an outside toilet block. We used the brick as hardcore and I spend many a happy day like an old road mender smashing up the brick with a sledge hammer and tamping it down to form the foundations for the drive. It has formed a free draining roadway that has resisted having a couple of giant 4x4s pounding over it for a decade. Weed growth hasn't been a problem. A dressing of shingle - the larger stuff helps to keep it looking suitable clean and tidy. The PITA is that it is overhung with trees and getting fallen leaves off it takes serious work. It's also not possible to use a blower or vacuum to remove the leaves.
To avoid weeds, a decent foundation is essential, be prepared to dig deep and to ruthlessly remove any roots that you encounter. Then fill it up with clean rubble. I think harry is talking carp again about the depth needed. We are on clay and gravel (valley floor) and the foundation for the drive was about six inches deep.
One possibility not mentioned here, that we use extensively at work, is Geoweb. This isn't a membrane, it's a cellular rubber structure that you peg down into the area to be turned into a road. Then you fill up the honeycomb strusture with crushed stone or whatever else is around. It's used widely in military engineering to build a road quaickly and in civil engineering to stabilise steep banks.
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weeds are held at bay because their roots can't penetrate the rubber walls, but weeds seeding onto the surface can still get established. Spraying with Pathclear helps.
%steve%@malloc.co.uk (Steve Firth) wrote in news:1k5ocpm.wibvr51wlimynN%%steve%@malloc.co.uk:
Thanks; I watched the video, and can see that suff may have uses in reducing erosion of slopes, but am struggling to see how it would be useful in creating a level driveway. (My driveway is almost exactly level, so there is little chance of any aggregate drifting out of place.
Tim Watts wrote in news:ptl4h8-1ov.ln1 @squidward.dionic.net:
Yes, that may be an option, thanks. It would certainly solve the weed problem.The tamping-down is just about within the scope of a one-man DIY-er too (eliminates the hiring of a compacter or roller, as needed with aggregate). I reckon my existing driveway (old compacted clay and limestone chippings) is probably solid enough as a base to concrete directly onto, once the humps have been skimmed off with a small bulldoser.
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