I am planning a flagstone walkway (dry laid) for a customer. She wants decorative pea gravel in the grout line areas. I have had success with poly-sand in the grout joints. Has anyone ever tried to put pea gravel in the grout joints while the poly-sand is setting up? Do you think this will affect how the poly-sand cures? Should I wait and sweep the pea gravel in the joints after the poly-sand has cured? Thank you for any input & suggestions!