How Polymeric Sand is Different
Joint sand isn't a stranger to paver installation projects, but polymeric sand isn't exactly the same thing as typical joint sand. The sand is treated with a polymer to give it special qualities to help your clay brick pavers stay in place. Applied dry, the polymer activates when you wet the sand, causing the grains to stick together with a flexible seal. This helps prevent erosion and reduce weed and insect problems in the joints. Because it's flexible, it continues to bind the pavers even if they shift over time.
Spacing Your Pavers
For polymeric sand to have the room it needs to bind together properly and hold the pavers in place from top to bottom, the joints between the pavers must be large enough. In most cases, spaces ranging from 3/16 of an inch to 1/4 inch work well with polymeric sand. If you space the pavers too closely together, not enough sand can fall all the way to the base, which creates weak areas in your paved area.
Using the Polymeric Sand
After installing your pavers, make sure they're completely dry. Any moisture on the pavers will bind with the sand, adhering the sand to the top of the paver. Pour sand on a small area -- about one to two shovels of sand per 100 square feet usually is sufficient -- and sweep it into the joints with a push broom. Sweep in two directions, perpendicular to each other, to make sure you fill all the joints adequately. Removing the excess sand from the tops of the pavers after filling the joints means sweeping it off or using a leaf blower to blow off the pavers. To finalize the installation, water the pavers well with a low-powered, wide stream of water. The object is to wet the joints, not pressure-wash them so the sand washes away before the polymer makes the grains adhere to each other. Wet the pavers thoroughly three times, waiting 10 minutes in between, to ensure the sand is wet throughout.
Take a Break for the Cure
Polymeric sand doesn't activate immediately. It takes time for the water to soak in completely, activate the polymer and help the sand adhere to the pavers. If you shift the pavers during this time, it could break the seal. Stay completely off the pavers for at least four hours. After four to six hours, it should be safe to walk across, but don't put heavy loads on the pavers for at least 24 hours after applying the water.