I don't claim to be any sort of an expert, but I can say that I have 2 1/2" of coarse washed sand as my footing and I've absolutely loved it every day of the 7 years I've had it in. I jump up to 4'9" (so want something that holds up to high impact riding). It's nice and springy and not terribly dusty and I would put it in any arena I built in the future. I have no idea how that compares to either of your sands (I would imagine that concrete sand is finer and that mortar sand is coarser but still with the fines?)....sorry I can't be of help there. Hopefully some footing experts will chime in!
(I would imagine that concrete sand is finer and that mortar sand is coarser but still with the fines?)
It's the opposite at least around here. Concrete sand is more coarse than mortar sand.
I'm pretty sure I've found my top footing though. In my area, the stuff I am getting is called concrete sand, which is sharp, angular more coarse sand. Mortar/Masonry is more fine and according to the guy I spoke with has more round particles and will shift more. I would think either would be good, but I'm going with the concrete.
I have one layer of concrete sand right over our clay base here, and it worked very well until this year, when we put in more french drains and had a super dry summer. So I put another 90 tons of a mortar/concrete mix. I ride in a ring close to here that has just mortar sand, and I don't think you want just that (looks like beach sand). I like my mixture quite a bit as it's easy to drag/maintain, can be ridden wet or dry, and is great for dressage or jumping. It also holds it's "eveness" if you will, even if the jumps sit in the same place for while.
The name either goes by means nothing. They can be completely the opposite 20 miles apart. Coarse, angulated sand is what you want regardless of what anyone calls it. There is no universally standard naming protocol for sand.
We got mortar sand in error...should have sent it back but it was dumped and left before we really noticed...like fine beach sand, which would be fine if we were building a BEACH!!! It blows away in the wind, gets slick in the rain, does not drain water well....but PERFECT for sun bathing!
Around here the best arena sand I've found on the Texas Gulf Coast is called 'sharp' sand. It is similar in appearance to concrete sand or mortar sand, but it has small 'pebbles' in it - smaller than pea gravel. It is the main visual defining difference. But, really, you cannot, as someone said, go by what anyone 'calls' it. Find the sand you love (I took a sample from our huge horse show complex down here) and then drag it around to different materials yards until you find a match.
I just got some for the first time and LOVE it. It is heavier than the red 'bank' sand that is most common around here and will not wash or blow away as easily. And has a nice 'crunch' sound to it when they trot through it and makes the horses much springier.
If you can't get "angular" sand/crushed granite, and are left with sand you want CONCRETE sand. It is also called C-33. It is made to industry standards since concrete must meet regulations. It is cleaner, less fines and more uniform. Morter sand has more fines in it. Washed sand is next after morter sand. And plain beach/river sand has the most fines in it. Beach sand is actually the worst since its particles are rounded.
When I did my arena I did it in 2 parts (long story, boring). The first was supposed to have WASHED sand. When I got home that evening, after there had bee 5 loads delivered and my kind loving husband had spread them, I discovered that the trucks who hauled went to the sand pit/quarries OTHER site and wound up with RIVER SAND. I had to suck it up.
When we did the other half, I specified ONLY concrete sand. Much more expensive mind you. But a world of difference.
My footing is a mix of 1/3 sand, 1/3 screenings (in the east it is called Blue Stone) and 1/3 Permaflex shredded rubber. I love it (even with the dustier river sand). That was 5 yrs ago and it is a lovely now as it was when we put it in.
THe other thing I learned that is the MOST important thing about footing (I spent 2 yrs researching it before I spent the money on it) is the BASE. And that is where it gets pricey. A rock hard, thick base is essential. It shold be thick and hard packed enough to be able to drive the dump trucks on it without any damage what so ever. If you get the dohicky that road constructions outfits use to measure compaction, it will be same as for correctly installed asphalt!!
I was lucky in that our soil here is rock hard so I didn't have to put in a fabric liner or anything under the base. But I had to really nag at the contractors about how I wanted the base done but got it the way I wanted it. And it is perfect (if I may say so myself!!)