There are two ways of laying paving stones: unbound, which means laying the stone on a pure sand bed; or bound, which means mixing bedding sand with sufficient cement to set the bed to a fairly hard consistency. Stones are set on the semi-dry mix without adding water. Natural curing begins after two to eight hours, and relies on moisture in the sand and encroachment from the subgrade and the atmosphere to initiate curing. Once cured, the bed hardens and prevents further settling from traffic, as well as erosion caused by the bed being mined by ants and groundwater.
Prepare the previously excavated paving area by running a vibrating plate compactor over the surface several times to create a load-bearing foundation. Once completed, the subbed must be even, but with a slight gradient to allow water to run off the finished paving.
Mix 10 parts coarse grained sand with one part Portland cement in a cement mixer. Do not add water. Run the mixer for five to 10 minutes to blend the sand/cement mix thoroughly together. Tip the blended mix into a wheelbarrow and lay it in the excavated area.
Rake the surface flat and keep adding mix until the required bedding layer thickness is achieved. When laid on top of the bedding layer, the pavers must protrude 3/8 to 1/2 inch above the surrounding terrain to allow them to settle during final compacting.
Stretch two string lines down each side of the paved area between wood stakes driven into the ground. Adjust the string around the end stakes so that the line follows a gradient of about 1:60 to allow for water run-off.
Lay lengths of 1-1/2-inch galvanised pipe screed poles three feet apart on top of the bedding mix parallel to the string lines. Have two helpers stretch another string across the side string lines at the highest point. Settle the pipes into the base mix with the top of the pipe level with the surface, and carefully measure the height from the pipe to the string with a steel measuring tape. Work your way downward and maintain the same distance between the pipe and the string while settling the screed poles into the bedding layer.
Place a straight four-foot plank across two screed poles at a time at the top end of the trench, and kneel in front of the plank. Work the plank from side to side and toward you while scraping the bedding mix level with the top of the screed poles. Pull excess sand toward the bottom end of the trench while working in sections until the entire surface is screeded. Lift the screed poles out, fill the grooves with base mix and smooth flat with the back of a plastic garden rake.
Lay the paving stones. Once the entire surface is covered, bed the stones in by working a vibrating plate compactor across the surface. Wet the paving down lightly with a lawn sprinkler. Tie construction tape around the paving for 24 to 48 hours to allow the bedding layer time to cure.
Things you need
- Vibrating plate compactor
- Coarse grained sand
- Portland cement
- Cement mixer
- Wood stakes
- 1-1/2-inch galvanised pipe
- Steel measuring tape
- Straight 4-foot plank
- Plastic garden rake
- Lawn sprinkler
- Construction tape