Bolting shale for mixed climbing

I'm from central N.Y. And it's loaded with shale cliff bands and excellent mixed climbing potential.
I'd love to have any suggestions before I go out and bolt it

Description of rock: overhanging layered shale with layers being 2"-3' thick and occasionally layers of dirt and choss

Ice flows from springs feeding out of the rocks and build up nicely but typically forms daggers that don't reach the ground Unless there's a polar vortex

I have no experience with shale and obviously no experience with the shale in your area. What I know is that shale can be either incredibly weak or suitable for putting a bolt in. It really depends on the shale in your area.

My suggestion would be to try to get with a geologist and/or material scientist in your area and get a sense of the compressive strength of your rock and any other info about your rock that you can get.

Any bolt that meets UIAA 123 specs tests against a 50 N/mm^2 block. If you find out your rock is weaker than that you probably need to look at long glue-ins (100mm or longer). If this is the case, talking to someone like Jim T from Bolt Products would be advisable.

If your rock is below 50 N/mm^2 I can't stress how I would advise you to talk to people who are bolting soft rock and learn as much as you can from them. You need not search beyond Mountain Project forums to see evidence of cases where bolts in soft rock have failed, luckily without tragedy. It could be that the best choice for your rock would be to accept that bolting it might not be the best idea. You'll have to make that decision once you've learned more.

Hopefully someone with more soft rock experience than me can chime in, but this is how I would approach things with the known quantity of things I know about bolting in green schist (50-70 N/mm^2) and very strong gneiss.

When shale is metamorphosed it becomes slate then schist and then gneiss, interesting but no real help!
Knowing the compressive strength doesn´t help, it can be almost anything anyway between about 10MPa to 150. The test blocks are made from 50MPa concrete because it´s a) the standard way to measure concrete strength BUT the strength of the bolt is determined by the tensile strength which is rarely if ever measured. Using concrete to a determined compressive strength is just a convenient way of doing things.
The problems with shale are a) it´s extremely variable b) weakened by water c) comes in layers stuck together with mud.
Bolt-ins are spectacularly useless in these kinds of rocks since it´s usually so soft, I´d be installing 300mm glue-ins VERTICALLY through the rock layers to try to hit as many different ones as possible. (In truth I wouldn´t, ice climbing doesn´t interest me. I´d get on a plane to somewhere warm and nice.)

Without getting in an argument about the difference between slate and shale, slate has issues because of large differences in the properties of the rock (strength) depending on the direction of the force. More at:

thebmc.co.uk/warning-issued…

Bottom line: large diameter glue-ins

I wouldn't trust any bolt in 2-3" bands of shale, especially with spring seeps in the wall. Shale is basically hardened clay.

If you must, I would go with 12" long glue ins and don't go taking big whippers on them. Most shale cliffs shed constantly, more with freeze thaw cycles. Basically it's all choss.

Master's degree in geology if that lends any credibility...

Thanks for all the responses, in regards to the last post the band's are up to three feet thick, I was only planning on bolting the six inch or thicker slabs

It might be best to just TR the cliff. Some places are just best left to TR and this sounds like one of them.

Placed a few bolts in shale and similar soft rock around southern Utah.

Best practices in my experience (no experience with glue-ins, sorry):
1. Use a rotary hammer, with care to keep the bit centered in the hole. if the bit rubs the side of the hole it will ream out and enlarge the hole real fast. Don't be surprised if a half-inch hole goes 4 inches deep in just 3-4 seconds.
2. Use Powers 1/2" by 4 inch bolt. Use only the older design, now available only in Stainless (link below). You'll need to use a stainless hanger to go with this. The newer design Powers bolts won't work in soft rock because they won't expand enough to bite the sides of the hole. In fact they might just fall into the hole and come right back out (did for me, couple days ago). No other bolt design comes close for usability in soft rock.

fixehardware.com/shop/bolts…

Just before placing the bolt, screw the cone in so that the sleeve rides over it and expands some and bites the hole. As you "gently" tap the bolt in, tighten it on an as-need basis as you go, so once it's seated, the sleeve has a head start on biting the rock. If done right, this should tighten up fine, just as in harder rock. Since the cone is 4 inches in, this should hold a substantial fall.

One caveat is that on the routes I'm installing there will be little traffic and only then by folks who will be wary about fixed gear. If you expect lots of traffic and/or these are for bolted sport routes with a high expectation of safety and convenience, then these bolts will probably quickly become spinners as the rock surface gets eroded, and the suggestions above might not be appropriate.