Remove 8 inches of topsoil from the site of the patio with a shovel. Level the subsoil with a rake and compress it with a tamper tool.
Lay landscape fabric over the tamped dirt to keep the gravel foundation from sinking in the ground.
Spread a 3-inch-deep layer of 3/4-inch gravel over the fabric, and tamp it.
Spray a coat of hot RC-250 over the first layer of compacted gravel. The "RC" stands for rapid curing. The material is liquid asphalt mixed with an oil solvent to make the asphalt easier to spread. The oil evaporates over time, while the asphalt hardens to the gravel as it cools, forming a stable base.
Build up the base with another 3-inch layer of 3/4-inch gravel. Tamp it over the hot oil and cover it with another layer of hot RC-250.
Spread a 2-inch layer of pea gravel over the oil. Rake it level and tamp the pea gravel into the oil. The top gravel will remain loose while the pea gravel touching the RC-250 will harden to the base. This setup prevents low spots from forming, but you’ll still need to rake the surface on occasion so it stays even.