How to Fill in Space in Between Concrete Pavement Blocks

Use sand, the traditional filler between concrete paving blocks. Sweep fine mason's sand over the blocks and into the gaps with an outdoor broom. Mist it with a garden hose to settle it into the holes, then add more sand until the gap is filled to the level of the paving blocks. Use a polymeric or locking sand to make a tighter bond; this sand has a special ingredient which will solidify the sand after it is dampened so it won't spread out of the gaps.

Fill concrete block spaces with dry cement or stone dust as an alternative to sand. Sweep the cement or stone dust, typically finely ground limestone, just like sand, until the spaces are full and even with the blocks. Dampen the cement or dust with a garden hose misting nozzle to solidify it. Use this technique especially if the gaps are larger.

Be creative if concrete blocks have wide spaces. Some concrete paving blocks are deliberately set with gaps of 1/2-inch or wider, even up to about 4 inches. Use pea gravel, small stone-washed rocks up to about 1/4-inch in diameter, instead of sand to fill 1/2-inch or 1-inch gaps. Pea gravel is multi-colored and provides a colorful decorative seam between concrete paving blocks. Lay small strips of sod between widely spaced blocks to make a checkerboard pattern.