Do I use concrete? Sand? What else for "locking" down some stones on walkway?

[DP]

A neighbor offered these square flags and I installed them between the driveway and walkway. I added the river rock pebbles around the perimeter and Neko has to get in the picture.
I have some rocks I've collected from our kayak trips to the Pine River in the northwestern lower Peninsula that I'd like to use in the two gaps in the middle. Petoskey stones are common there as well as some other corals and cool-looking rocks. I need to secure them but just sticking them in the sand I have in there won't secure them and I'd hate to lose them by having foot traffic kicking them away, shoveling, etc.
Is there something that isn't gray to put in the gaps to secure the rocks or something I can mix with sand to secure them?

[Ombligo]

perhaps a base of small river rock bound with epoxy (a technique used around pools), then set your stones on top bound with same epoxy?

It would look nicer than concrete (which would work) but at a higher cost.

[fromish]

There is a special sand called polymeric sand (Home Depot, Lowes) that stabilizes pavers and prevents weeds and insects from causing problems with the sand. It's not as cheap as playground sand, but it lasts in my experience with paths and patios made of pavers.

[Yoyodyne ArtWorks]

fromish wrote:
There is a special sand called polymeric sand (Home Depot, Lowes) that stabilizes pavers and prevents weeds and insects from causing problems with the sand. It's not as cheap as playground sand, but it lasts in my experience with paths and patios made of pavers.

I thought of that too, but wonder if it's effective when the gap between the stones is that large. We use it on our patio and it works great, but the gap between pavers is less than 1/4th of an inch.

[rgG]

Looks like you should just get Neko to hold them down for you.

We used to have a small white dog, Tootie, that would photo bomb every picture we took, it seemed.

[OWC Jamie]

Winter rain/freeze/thaw will just pop them out of the ground

[Buzz]

It's labor intensive, and kinda expensive, but cut some mesh screen to size to fit into space between the flags and walkway, then pour a layer of liquid rubber (like Flex Seal*), and carefully arrange the rocks, pressing each one down to make sure it's seated securely. By the time you're done, take a squeeze bottle of the stuff, w/ a small nozzle, and seal around the larger exposed areas of the rocks that the nozzle will fit in. Bring some of that polymeric sand w/ you, and sand the larger spaces shortly after manually sealing them (seal a few, then go back and sand, repeat until done). When the whole sealing and sanding is done and dry, then you can polymeric sand the entire rocky area to additionally lock the rocks in. If done correctly, you should get a lot fewer "pop rocks".
==

*Vulkem Sealants are another good/excellent option in polyurethane, and they have stuff that was originally developed for installing rock patios (by one of my best friend's dad, back near cbelt3's backyard... Dick lived in Shaker Heights, w/ company in neighboring Beachwood, both in the burbs of Cleveland).

[DP]

Thx, all, for the tips!

[tenders]

Epoxy is not stable in sunlight and will turn yellow and chip in short order for this application.