After a few years, paver block patios and walkways often develop low spots. However, these areas can be brought back up to grade with a few bags of sand, a length of pipe and a screed board.
First, remove the pavers from the low area. If they're packed in tight, use a screwdriver to lever the first paver out, levering each end a little at a time and tapping on surrounding pavers until you can pull out the paver (Photo 1).
Make a screed board long enough to rest on the level pavers around it. Then notch the ends 1/8 in. less than the depth of the pavers. If the area is large or against the house or grass, set a screed pipe along one side and level it against the pavers you're matching. If you're trying to match a sloping walk, shim the level at the downhill end to match the slope (Photo 2).
Fill the low area with coarse, all-purpose sand, then screed it level (Photo 3). Use a trowel like a spatula around the edges to scrape away any excess sand.
Brush any old sand off the sides of the pavers, then set them back into place and drive them down until they're flush with the other pavers (Photo 4). Spread dry sand over the pavers, tamping and sweeping until the joints are completely full.