There are two procedures for grouting patio pavers, and neither is difficult for the average home handyperson to accomplish. The first way requires the use of a grout bag filled with mortar or grout, and the second requires the use of a stiff-bristled brush and semi-dry grout or mortar. Both ways are equally effective, so the choice really depends on the materials and tools at hand.
Before you grout any pavers, you should seal them first. This may seem like extra work, but it prevents staining of the pavers by the mortar or grout, which can be hard to clean up after the grouting has been completed. You can use any commercial concrete waterproofer or sealer. Allow the sealer to dry for 24 hours before proceeding to get the best results.
Grout bags have been used for many years for successful and quick completion of paver grouting; you can purchase them at any hardware store that sells masonry tools. Typically, a grout bag, which is 24 inches long and conical in shape, is filled with grout or mortar and squeezed tight from one end, very much like a cake decorating bag filled with icing. The tighter you squeeze from one end of the bag, the quicker the contents squirt from the ½-inch hole at the end. The tip, which has the ½-inch hole, can be inserted between paver joints while the mortar runs out the tip. This method will prevent the grout from spilling out onto the pavers and staining them.
Dry sweeping can be done easily on a clear day when no rain is expected. Mixing the grout or mortar mix dry and adding a small amount of water will allow you to sweep the grout into the paver joints quickly and easily. Making sure that the pavers have no excess debris on the surface before you begin will help keep the grouting clean and effective. The grout mixture should have the consistency of damp sand. A hand broom is recommended; however, you may use a push broom if this is easier. After the grout has been swept into the paver joints, wash off the surface of the pavers with a fine mist from a water hose. Use a brick thumb jointer to joint the grout joints smooth after you have wet the mixture.