Ideal Paver Base
Your pavers need to distribute weight across the entire pathway as you walk across the surface. To achieve weight distribution, a 4-inch thick gravel layer is the common base for your paver walkway. After leveling the gravel, you also spread 1 inch of sand on top of this base layer. This sand layer provides a setting bed for the pavers. Using a plate compactor across your laid pavers, they slowly travel 1/4 inch into the setting bed, essentially locking them into place. Other adhesive materials do not provide a soft base for pavers and may cause cracking during installation.
Along with the setting bed, sand also fills paver joints. Instead of using an adhesive, multi-sized sand mixtures, such as mason's or sharp coarse river-washed types, are spread and tamped down into the walkway using a plate compactor. As the sand jostles into place, both fine and large particles lock together. However, pure fine sand does not provide a locking joint and may actually slough away from the walkway in heavy rains. Verify your sand's mixture type before spreading it into the pathway. Joints with a minimum 1/16-inch width provide a buffer between pavers to prevent cracks and chips through friction. In fact, if you need to remove a paver in the future, it is easily accessible when jointed in sand. Simply lift the paver out of place and replace it without harm to other surrounding blocks.
Mortar or Cement Disadvantages
Using mortar or cement between your pavers creates a ridged walkway. Any uneven weight across the pathway slowly breaks the joint adhesive down and subsequently cracks pavers. Cracked adhesive joints often lead to weed infestations as well. Cement can also stain pavers if it hardens on the walkway surface during joint installation. Sand cannot stain your new walkway and creates a flexible surface for normal pedestrian traffic through your garden.
If you live in a considerably rainy region, you can mix additives into your joint sand to stabilize the pavers further. You simply sweep the sand and additive mixture into the joints using a broom, but activate the additive through wetting the walkway afterward. Your sand essentially hardens into a more secure locking joint to prevent water and sand runoff during storms. Your walkway still benefits from a flexible surface to reduce cracking but is more waterproof to protect your joints as well.