Build or place forms for the sidewalk as for a normal poured concrete sidewalk. Use 2-by-6s, 2-by-10s or plywood for the body of the forms, depending on the scope of the project, and lace wooden stakes to brace the forms in place. Oil the forms with a form lubricant or motor oil.
Prepare the concrete for the pour. Rather than use only standard sand or gravel aggregate, mix in the desired aggregate.
Pour the concrete into the form and level the top of the poured concrete with a wooden board.
Check the surface of the pour regularly to determine whether the aggregate is ready to be exposed. Do this by lightly brushing a small area of the concrete surface with a stiff-bristled broom. When the concrete is ready, this brushing will remove surface mortar without overexposing or dislodging the pebbles.
Spray the surface of the poured concrete gently with water.
Brush the surface lightly with the stiff-bristled nylon broom to loosen a thin layer of concrete.
Repeat this gentle spraying and brushing until the aggregate is exposed to the desired depth. Let the sidewalk cure as with standard concrete.
Apply an exposed aggregate sealer to the concrete surface about three weeks after the pour to keep aggregates from loosening. Ensure that the surface is clean and use a paint roller to apply the sealer.