Bob meets with Brian Kallmeyer from Unilock to talk about the Unilock tumbled concrete pavers. The product starts out as a high density (minimum 8,500 PSI mix) concrete paver. The density is achieve by taking a pretty dry mix with good aggregates like local granite that's put in a 3-story machine that presses it to a very high compaction and compression. They use a standard portland - no more than a typical wet concrete. Originally to tumble the create the antiqued pavers, they would just throw the fresh, shiny, square pavers into an old cement mixer and roll it around. The process has since become more elaborate to meet the growing demand. The resulting product is easy to work with. Unlike the natural stone that it duplicates, these pavers have been made in a mold so they are very dimensionally stable. They can be cleanly cut using a lever action on a guillotine cutter.

Nick Pastore, certified Unilock installer, finds the Unilock product easier to install than a natural stone like a Belgian paver because they are all uniform�smooth edges, square, always the same dimensions. To prepare the bed he first put down a 12 inch compacted gravel base and then laid a regular washed sand bed on top of the compacted gravel. He uses 1 1/2-inch aluminum electrical conduit on top of the gravel base to establish a proper height - setting the conduit to any pitch he may need to achieve, fills in between the conduit with sand, and then screeds over it with the straight edge of a 2 x 4 to set the sand base. Then he removes the conduit, fills in with sand, trowels over it, and begins setting the pavers into place. The pavers are laid and tapped into place, making sure they're all jointed together well. Settlement is the biggest challenge. A well compacted base is the best defense. They use a vibratory plate compactor to tamp everything down. In tight areas there's a lot of handwork with mallets and the like, but in larger areas they do it all by machine. To deal with curves in the layout they take a wet saw and cut the paver. It's a straight cut on a curve. The cut paver will fit in and the joining sand will fill it in. Finally the polymeric joining sand is swept over the entire work area and the compactor is run over one more time. Because a modular pavement will want to creep outward, Nick's crew uses a PVC edge restraint with spikes that are driven into the ground to hold the restraint in place. The edger only picks up the bottom half of the stone allowing the landscaping to come right up to the edge of the pavement creating a contiguous surface.

Bob meets with Mark Marini of Schumacher Landscaping to discuss the installation of the bluestone pavers on the lower terrace. Bob helps lay several of the stones and watches as a stone corner is cut to fit around a planter box.