OK. This might be a bit of a crap explanation, but here goes!
I have a friend who's involved with Hampshire Trailwatch. They need some material for surfacing an offroad trail. She's done some homework and discovered that some Scottish (I'm not sure which) trails are surfaced/constructed from a material that's more of a shale material than a limsesone scalpings, i.e. the particle shape is flat rather than rounded/angular when it's crushed, and this stuff seems to build longer lasting surfaces. (When a stone flicks out it doesn't leave a hole)
Now, I work in a quarry and I know building materials reasonably well, and I know this isn't a locally available material. BUT, if I can fing out it's exact technical description, (As in we call Sharp Sand: 0-4 MP GF85 Sand, to BS EN 12620:2002, something along those lines!) I can make enquiries to see if I can get it for them down here! I only know sand, gravel and limestone materials in the south really!
Maybe even where it came from? (Which quarry, or the quarring company?)
So, any Scottish trailbuilders know what I'm on about, by any remote chance?
Many thanks! 😀
Its known as "MOT Type 1"
Its used for road construction "Ministry of Transport type 1"
Normally Granite chippings and 20mm down to Dust
Hope that helps
Cheers
Dom
That's interesting.
Surfacing offroad trails with brought in materials?
Surely it then ceases to be "offroad" and becomes a road, albeit a narrow one.
Up here we use materials found adjacent to the track.
What's that grey stuff on Whites Level called? I hated that it was like a towpath.
Sadly, not everywhere is littered with decent trailbuilding Stone
What choice do you have if you want to create an All weather, high traffic surface through a forest when your subsoil is sand / Clay / Chalk..... 😥
And the only stone to be found is Flint 😯
Its known as "MOT Type 1"
No. It isn't. Sorry. 🙂 I know exactly what that is.
At least, if it is, it's not limestone T1. And granite would crush to an angular shape much like limesone... That's specifcally NOT what we want! 🙂
They're called "pebbles" Pete. To be precise, the ones you're looking for are officially known as "small grey flat pebbles".
Hope that helps..
DrP
You should stick to tattoing your hands! 😉
Pah - that's so 4 minutes ago.....
I'm into Aggregate and Tarmac now 😉
DrP
Is there nothing available locally that fits the bill?
if all the trails everywhere have the same surface it does rather reduce their attraction to visitors, I'd think?
Here's the spec I used to use:
Crusher run stone(80mm to dust) With high fines content, with a surface layer of compacted dust laid down wet (it is imperative that all stone is compacted as soon as it goes down otherwise the fines will get washed out and it will be useless) to a minimum fill depth of 80mm. Additional exposed stone may be embedded within the trail edge or tread as trail features or to denote trail line
She'll be talking about the stuff found at, for example Gwydyr - which unless I'm much mistaken is clay shale.
which unless I'm much mistaken is clay shale.
Yeah, along those lines. Flat particle shapes anyway. Not knowing much about it, I'm just wondering how durable clay shale is?
I've been doing a resurfacing job down the road and I've got a bit of tarmac left over.
I could do it cheap for cash. 😉
Try emailing the Hub at glentress perhaps?
We mostly follow what Z-E has described there. However, we found that with the local gritstone rock as a trail base that something with a smaller maximum particle size was preferable, it filled gaps and "knitted" with the underlying surface better. Personally, I found a lot of the larger fraction pushed out and swept away to the edges.
We typically order 60 or 40 mm to dust, limestone. We often ask for extra dust but whether they really do and if it doesn't separate out / stay stratified in the wagon / stockpile who knows.
Never bothered with the dust layer and wetting. Typically it wasn't possible where we built (no nearby water) and just meant yet more stuff to barrow for ages. Seems to have worked OK.
Sure a brand new section of limestone surfaced trail looks a bit "yellow brick road" at first but it performs better, being naturally cementitious. I'd rather trails were durable (and therefore, on one measure, "sustainable") in the longterm than get too precious about the materials origins and fit with local geology. Plus, after a short while the mud, leaf litter etc makes it indistinguishable from the rest of the forest.
By comparison the last contractor built section used rock crushed on site with an attachment to an excavator. This was then mixed with site won sandy clay. It was OK but we're finding a couple of years later a lot of the fines are washing out and the trail is wearing heavily. This is probably a combination of the construction material and the hammering this section gets as it's more open / faster / gets "DH'd" on.
Personally I'd go for what can be bought locally as hauling anything far is likely to increase the costs, probably a lot. However, you're better placed to decide that than me 😉
I'd be interested to know what the material you're looking for is though so if you do find out please let me know. Imagine you could try the FC ranger in Scotland responsible for hte 7 Stanes? Forget his name but there's always google. Was interviewed in MBR I think, Andy Hopkins??
However, don't be surprised if it's site won stuff as FC like that, saves a lot of cost. If it is it's unlikely to be a BS grade etc.
We used to use Breedon Amber gravel round Notts for cycle/equestrian routes http://www.breedongoldenamber.co.uk/ but I think it's too expensive for the taxpayer's purse these days. It packs down really firmly under a roller and resists wear and tear from horses fairly well.
There's a reason 40mm to dust crushed limestone is used, it works. Yes when it first goes down it can be a bit smooth but if it's laid over a foundation of stone (we use gritstone from collapsed dry stone walls) after 6 months or so it gives quite a good 'natural' feeling surface.
I would imgaine the shale has been used because it's locally available rather than it's inherent superiority for trail building. I'd guess for every piece of shale flat there'll be a piece sticking up ready to get flicked out (although I can see what you're getting at, we had a similar issue when we laid the foundation course of one of our trails badly, los of stones sticking up through the limestone that then got knocked out leaving voids for the water to pool in).
The only shale used at Gisburn (which was already on site) turned out to a mudstone so was very succesful.
cr500dom - Member
...What choice do you have if you want to create an All weather, high traffic surface through a forest when your subsoil is sand / Clay / Chalk.....
You're probably right. Maybe everyone should be riding around on proper fat tyres - 4" or so - makes less of an impact than a footprint then.
Thanks for the advice fellas, I'll pass the info on, much appreciated
🙂
Imagine you could try the FC ranger in Scotland responsible for hte 7 Stanes?
Mail me and I will send you his addy. May be a bit of a wait for a reply tho, he is busy doing winter/frost/snow damage repairs and Xmas hols coming up.
The advice re lots of dust rings a bell as does wetting and compacting. I think the current thinking is something like 6 passes with one of those whacker plate things. Drainage is also very important.