Technical Resource Guide_WEB_BEL25-D-516650 - Page 14 of 84

14 | belgard ® product installation guide | belgard.com | 877-235-4273 EDGE RESTRAINTS Restraints hold the pavers tightly together, enabling consistent interlock of the units across the entire pavement. They prevent pavers from spreading due to horizontal forces from tires and minor settlement. Edge restraints are designed to remain stationary while receiving occasional impacts from tires. There are two general types of edge restraints. Those made elsewhere and installed at the site include precast concrete, plastic, cut stone, aluminum, and steel. Restraints formed on-site are made of poured-in-place concrete. Full-depth precast concrete or cut stone edging generally extends the depth of the base material. They can be compacted soil (not subject to heaving), compacted aggregate or concrete backfield. The preferred method of installation with vehicular pavements is for the curb to rest on the compacted aggregate road base. Partial-depth precast concrete edge restraints may be used for residential and light-duty commercial applications. These precast units are anchored on a compacted aggregate base with steel spikes. The spikes are typically 3/8 in. diameter. Depending on the design, the top on the concrete edge can be hidden or exposed. Aluminum and steel edging should be selected to provide a smooth vertical surface against the pavers. L-shaped edging provides additional stability. Stakes fastened to the edging should be below the pavers or on the outside of the restraints. Steel should be painted or galvanized so that rust does not stain the pavers. Spikes to secure steel and aluminum edging should extend well into the base course. Consult manufacturer's literature for recommended spacing of the spikes. Aluminum and steel edgings are manufactured in different thicknesses. The thickest edging is recommended when pavers are subjected to vehicular traffic. Plastic edging installs quickly and will not rust or rot. Plastic edging should be specifically designed for use with pavers. It can be used with light-duty residential, commercial or on some heavy-duty industrial applications, depending on the design. It should be firmly anchored into the compacted aggregate base course with steel spikes. Consult the manufacturer's literature for the recommended spacing of the spikes. Edging for planting beds and lower gardens is not an acceptable restraint for interlocking concrete pavements. Elevations should be set accurately for restraints that rest on the base. For example, 2 3/8 in. thick pavers with 1 1/4 in. of bedding sand would have a base elevation set 3 in. below that of the finish elevation of the pavers. This allows 1/4 in. settlement from compaction and 1/8 in. for minor settling over time. Restraints formed on-site, poured-in-place concrete curbs, or combination curb and gutters required by municipalities make suitable restraints for pavers. Exposed concrete edges should have a 1/8 in. radius edge to reduce the likelihood of chipping. As with precast, the side of the curbs should extend well below the sand bedding course. Troweled concrete from a bag mix, or batched on-site, can be applied without forms against edge pavers and on the compacted base if the mix is polymer modified to be frost damage resistant. This type of edge restraint is typically limited to warm-weather climates and non-vehicular applications. If the top of the concrete edge is recessed and slopes away from the pavers, grass can grow next to them. The depth below the surface of the pavers must be sufficient to prevent the concrete from becoming a heat sink that dries the grass and topsoil. This edge restraint is suitable for pavers subjected to pedestrian traffic and for residential driveways. Troweled edges should be at least 6 in. wide. Steel reinforcing should be placed in the concrete to increase service life. SAND SETTING BED Loose screed the washed concrete sand to an uniform thickness of 1 in. over the compacted base course. In no case should the sand be greater than 1-1/2 in. thick. Do not use masonry sand, play sand, stone dust. If the edge restraint has already been installed, the screed board may be notched to ride on the edge restraint on one or both ends. The notch should be cut to allow for the screeding of a 1 in. thick sand layer. If the edge restraint cannot be used to carry the screed board, screed rails must be used. The rails should be sized to allow for a 1 in. thick sand bed. For example, a 3/4 in. iron pipe (3/4 in. is the inside pipe diameter) has an outside diameter of approximately 1 in. Place the screed rails parallel to each other and close enough together to enable the screed board to be pulled along the rails without falling off. Set the top of the rails to the desired elevation below grade lines and stabilize by hand packing sand along both sides of the rail.