The sand bed was a layer of sand spread on the ground before you laid brick or stone. The sand was the cushion between the paver and the earth. The earth was rough. The paver was flat. The sand filled the difference. You screeded the sand flat with a board and set the pavers on the sand and the pavers sat level because the sand was level. The sand did not hold the pavers. The pavers held each other. The sand just gave them a flat place to sit.

The sand was sharp sand. Not beach sand. Beach sand was round and the round grains rolled under the pavers and the pavers rocked. Sharp sand was angular like the gravel in the foundation. The angular grains interlocked and resisted movement. The mason spread the sand two inches deep and screeded it with a board that rode on two pipes set at the right height. The pipes were the guides. The board was the blade. The sand between the pipes was the surface. The mason pulled the board toward him and the board flattened the sand and the flat sand waited for the brick.

You swept sand into the joints after the pavers were laid. Joint sand. Fine sand pushed into the gaps between the pavers with a broom. The sand fell into the joints and filled the space and the filled space locked the pavers together. The pavers could not move sideways because the sand in the joints resisted the movement. The sand was the mortar of the dry-laid patio. The sand did not bond. The sand wedged. The wedging was enough. Rain washed some sand out and the homeowner swept more sand in and the cycle of rain and broom kept the patio tight for twenty years.

Polymeric sand replaced regular joint sand. Polymeric sand has a binder that hardens when you wet it. The binder locks the sand in the joint and the locked sand does not wash out. The polymeric sand is permanent. The regular sand was temporary. The regular sand needed the homeowner and the broom. The polymeric sand needs nothing. The polymeric sand turned a maintenance task into a one-time installation. The homeowner no longer sweeps sand into the patio joints on a Saturday afternoon. The homeowner no longer kneels on the patio with a bag of sand and a broom. The kneeling was the relationship between the homeowner and the ground. The polymeric sand ended the relationship.

See also: Gravel, Cobblestone