The joints between patio pavers are usually filled with sand, which has a tendency to wash out of the cracks over time. PowerLoc Jointing Sand from Quikrete is a polymer-based product that prevents it from washing out or cracking. Simply pour it out and sweep the jointing sand diagonally into the cracks with a push broom. To lock it in place, mist the surface down with water from a sprayer, going over it three times within an hour, and let dry.