Masonry Magazine December 1992 Page. 27
Edge Restraints
Many different types of edge restraint materials exist, including brick, rigid plastic, wood, stone, steel, aluminum and concrete. Existing walls or structures may also be used as an edge restraint. The particular application and site conditions determine which material to use. Any of the materials previously listed can be used in light traffic applications. Only concrete, brick or stone embedded in concrete, some varieties of rigid plastic, or metal should be used in areas subjected to light or medium traffic. Heavy traffic applications require cast-in-place concrete, granite or curbs of equal strength. Asphalt or an asphalt pavement does not provide adequate edge restraint for paving subjected to vehicular traffic.
Edge restraints are necessary in mortarless brick pavements as they hold the pavers together and prevent spreading and movement of pavers due to horizontal traffic loads. Intermediate restraints may be used within the pavement when there is an interruption in the paving surface or on sloped or curved areas. Intermediate restraints will provide additional thrust resistance to traffic loads and pavement creep.
Edge restraints are not necessary in mortared brick paving but may be used for aesthetic reasons, to reduce chipping of perimeter brick or to control landscaping. Any of the edge restraint materials mentioned may be used.
Expansion Joints
Due to differential moisture and temperature changes, allowances for movement of various materials which comprise the paving assembly should be considered. Expansion joints are used in the brick paving to accommodate these movements. Expansion joint size and location vary for each paving assembly relative to climate, location, orientation, paving unit color and exposure to solar radiation. Although there are numerous formulae and guides for predicting the anticipated movement of materials, proper joint placement often depends on experience gained from similar past paving applications, along with good engineering judgment.
Mortarless brick paving usually has the ability to move slightly and accommodate size changes. Consequently, expansion joints in mortarless brick paving are not generally required.
Placement of expansion joints is critical in mortared brick paving assemblies. Expansion joints in brick paving which is bonded to the base must align with control joints in the concrete base below. If this is not possible, a bond break between the mortar setting bed and concrete slab must be used. However, this may not be sufficient to prevent cracking of the mortared brick paving near the control joint location. A typical expansion joint in mortared brick paving is shown in Fig. 9.
In most cases, an expansion joint spacing of 16 ft (5 m) in exterior mortared brick paving is adequate. Expansion joints in interior mortared brick paving may be spaced a maximum of 24 ft (7 m) apart. However, these distances are dependent on many factors and local conditions including