Masonry Magazine December 1992 Page. 29
Expansion Joints
Expansion joints are used to relieve compressive stresses in a brick paving system. These joints are typically filled with appropri-ate expansion joint fillers. The top of the joint is sealed with an elastomeric sealant.
Membranes
Membranes are used in brick paving applications to sep-arate layers in a paving system, accommodate differential movement or serve as a waterproofing element. Membrane materials include geotextiles, sheet membranes and liquid membranes.
Flexible Base Pavements
In flexible base applications geotextiles may be used to separate layers. In some cases, poor soil conditions may warrant the use of a geotextile to prevent subgrade soil from migrating upward into the com-pacted subbase or base. In other cases an open-graded, stone base may require a geotextile above it to prevent the sand setting bed from filtering down through the base. The open-ing size of the geotextile should be small enough to prevent sand filtration. Geotextiles can also be used to prevent ero-sion or used to reinforce the subgrade. If used to reinforce the subgrade, the sections of geotextile must be lapped a minimum distance. Consult the geotextile manufacturer for specific recommendations. Building felt and other imper-vious membranes should not be used since they inhibit drainage.
Rigid Base Pavements
Mortared brick paving and con-crete bases have considerably different thermal and mois-ture movements. In applications where the spacing between expansion joints is larger than 16 ft (5 m), it is important to break the bond between the rigid base and the mortar set-ting bed by means of a membrane. Polyethylene plastic sheets or building felt can be used as the bond break. The bond break will allow the brick paving surface to move independently of the base, but still permit the paving sys-tem to provide the necessary transfer of loads. Bond breaks should be used when the brick expansion joint and concrete control joint are not aligned.
Waterproofing is used in roof deck applications where it is important to prevent water penetration. The waterproof-ing is often applied in liquid form but can also be sheet mem-branes. Care should be taken to prevent damage or penetra-tions to waterproofing membranes during pavement construction. Technical Notes 14B provides details for brick paving over roof decks.
Slip and Skid Resistance
The slip resistance characteristics of a paving surface relate to pedestrian traffic, while skid resistance characteris-tics relate to vehicular traffic. Slip and skid resistance are measures of the slipperiness of a surface. A surface with high slip or skid resistance is relatively safe, while a low resistance may indicate a hazardous surface. Both slip resist-ance and skid resistance are adversely affected by water on the surface of the pavement.
It is the surprise of walking from a slip resistant surface onto a wet or nonslip resistant surface that causes many falls. Since the slip resistance relies on the microtexture of the paving brick, a brick with a rougher or wire cut surface will have a higher slip resistance.
Skid resistance measures the potential of vehicles skid-ding on the roadway surface. The skid resistance depends upon the macrotexture of the paving surface. Brick texture, joints between pavers and pavers with chamfered edges have positive effects on the overall skid resistance of the brick pavement. Skid resistance values of brick pavers fall within the range of concrete and asphalt pavements [5].
Over time, the skid resistance of all paving surfaces decreases because of the polishing effect of traffic. The skid resistance of most brick paving is initially very high and decreases while in use, approaching an equilibrium con-dition after one year [8]. The skid resistance values are also affected by seasonal factors.
Aesthetics
The visual impact of brick paving results from the inter-play of many factors including size, shape, pattern, color and texture. An endless variety of bond patterns can be achieved with brick paving. The most popular paving pat-terns are shown in Fig. 11. These patterns may be laid with or without mortar joints. Patterns such as herringbone, basketweave variations and some running/stack bond com-binations require brick pavers with lengths twice its width when laid in mortarless brick paving. Two examples of paver sizes appropriate for mortarless paving bond patterns are 4 in. (100 mm) by 8 in. (200 mm) and 3% in. (95 mm) by 7% in. (190 mm). For mortared brick paving, nominal dimensions are often used where the paving unit dimensions listed include the mortar joint thickness. Thus, when lay-ing out patterns with mortar joints, it is best to use nominal dimensions.
Brick pavers are manufactured in a variety of colors such as reds, browns, buffs, grays and others, including ranges and blends of colors. The type of traffic on the paving units should be considered when choosing color. For example, a light colored brick will show dirt and stains more than a darker colored brick. Also, color patterns can serve a func-tion. Two or more different colors can be used to create pat-terns which guide traffic, such as marking traffic lanes or parking spaces.
SUMMARY
This Technical Notes describes brick paving assemblies and covers their design and detailing. Critical design con-cerns in brick paving systems include base preparation, drainage and load resistance. Pertinent design criteria is provided to aid the development of a proper brick paving system. The details provided in this Technical Notes will provide an adequate pavement system for most applications.
The information and suggestions contained in this Tech-nical Notes are based on the available data and the experience of the engineering staff of the Brick Institute of America. The information contained herein must be used in conjunc-tion with good technical judgment and a basic understand-ing of the properties of brick masonry. Final decisions on the use of the information contained in this Technical Notes are not within the purview of the Brick Institute of America and must rest with the project architect, engineer and owner.