Sand plays an important role in the installation of paver walkways. It is actually used twice during the paver installation process for different purposes. It's important to keep both of these uses in mind when choosing sand for your paver installation since each use has different sand requirements. Choosing the wrong sand can result in your pavers sinking, shifting or having other problems over time.
Sand is used in two parts of the paver installation process. A bed for the pavers is dug out and filled with gravel or crushed stone, then topped with a layer of sand to cushion the pavers. Once the bedding sand is in place, you smooth it, compact it and put the pavers into place on top of it. Additional sand is swept over the pavers, filling in the spaces between them to create an even surface. This sand is compacted as well, then dampened with a hose to help pack it into the paver joints.
The best sand for your bedding layer is a sharp, coarse granular sand with grains of similar sizes. As you compact the bedding sand, the edges will grind together and lock the surface of the sand layer in place. This produces a smooth surface to place your pavers on that won't easily shift or erode. Using a fine-grained sand or sand with smooth edges won't create this locking effect, increasing the likelihood of shifting or sinking later on.
The best sand to fill the joints between your pavers is one that has multiple grain sizes and sharp or ragged edges such as river-washed sand. The multiple grain sizes ensure that the joints are well-filled while allowing for the natural expansion of paver materials due to temperature changes. The ragged edges ensure that the filler sand will lock together to create a smooth surface once it is compacted. Fine-grained sand or smooth sand won't produce this effect and will likely wash out or be blown out of the joints over time.
Polymeric sand is an alternative option for filling paver joints. This sand is coated with a water-activated polymer that bonds together when you dampen it. The bonding polymer produces an even stronger fill joint than standard filler sand, preventing erosion or other damage by bonding the grains of sand together to create a solid water-resistant surface. Polymeric sands made with organic components have the ability to "self-heal," softening slightly during rains or other times when water is introduced to fill any slight gaps that occur over time. Other polymeric sands made with synthetic polymers don't have this feature but do offer increased resistance to weeds and other plant growth.
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