Wanting to build a caliche road up a hill. Steepest part is about 15% grade for ~600ft.

Is that too steep a grade for a caliche road?

That will rut out in a decent rain. You're gonna need some diagonal swales to act as check dams to prevent erosion.

Have no idea what a diagonal swale is and a cursory google search didn't help

Just a small little ditch across the road at an angle to divert water off.

ConfidentAg said:

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Have no idea what a diagonal swale is and a cursory google search didn't help

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And wing ditches.

And a really good crest across the center of the road so the water immediately runs off the road rather than down it.

Would tractor trailers have any issues driving up that type of grade?

Wing ditch is what I was looking for. Haha. Thanks.

ConfidentAg said:

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Would tractor trailers have any issues driving up that type of grade?

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That is an 8.5% slope, which is pretty steep.

Can a tractor trailer do it? Likely, but it would have to be under ideal conditions. There are only a handful of grades in Colorado that are 8% or more, and those are paved roads.

The answer is no. That's not going to be something you want to do.

At that grade your better off using crushed limestone that will pack hard as concrete after it gets wet a few times .. you still need to make sure you have some little ditches for water .. but if you "crown" the base a little it will form a natural ditch on the sides since the middle is higher

Depending on how far you are from a limestone pit (New Braunfels area for sure) sometimes crushed limestone is cheaper than coleche

We put some crushed limestone roads in at our ranch .. a Friend did the work w a dozer and one of those big heavy highway rollers .. that **** was so hard after he rolled it you couldn't cut into it w a shovel if you wanted

I'm out in Val Verde county and I'm pretty sure what I'm calling Caliche is limestone. I have a huge pile of it on my property

Caiche is a conglomerate of larger materials and fines, usually has limestone as the aggregate. It compacts well and forms a hard "concrete" like consistency after it is compacted and gets wet. It usually has calcium carbonate as the binding mineral, but other stuff is there as well.

You want fines in addition to the larger aggregates as the fines are what helps lock everything into place and allows it to form a more solid base whereas just crushed limestone or other material that doesn't have the fines won't compact and adhere to itself and you lose it over time.