Clean the surface of the concrete with a broom to remove any loose dirt or debris. Power wash the surface after sweeping to remove tough dirt deposits. If no drain is present, damp mop the concrete with a pH-neutral cleanser and warm water. Rinse with clean water and allow the concrete to dry.
Pour the pebbles into a pile on the concrete slab.
Mix the two-part epoxy in a five-gallon bucket. Stir the epoxy for five minutes to make sure it's thoroughly mixed. Mix only enough epoxy and pebbles to cover a spreadable section before the epoxy dries.
Pour the epoxy over the pebbles on the ground. Have an assistant fold the epoxy into the pebbles, using a spade to mix them together until all of the pebbles are wet with the epoxy.
Spread the epoxy-covered pebbles over the surface of the concrete with a trowel in an even layer ¼-inch thick. Wipe off the edge of the trowel with acetone to remove sticking epoxy and pebbles during the spreading process. Work from the far corner of the concrete slab to an exit area. Recreate expansion joints as you go along by slicing the edge of the trowel through the epoxy along the concrete joint lines.
Allow the epoxy 24 hours drying time before using the surface.