Brick Paver poly Sanding is popular and recommended for all brick paver patios, walkways, and driveways. Poly sanding is a phase completed before brick paver sealing. Unlike regular sand that washes away with rain, poly sand seals joints effectively. As a result, this prevents water from getting underneath. Otherwise, the pavers can erode the base underneath, and allow freezing in the winter to cause the pavers to rise and shift.