Masonry Magazine December 1992 Page. 25
Rigid Base Pavements
Mortarless or mortared brick paving may be laid over a rigid concrete base. The brick paving assembly shown in Fig. 4 is applicable for mortarless paving over a new or existing concrete slab. Only residential pedestrian applications are appropriate for this assembly. A similar assembly is shown in Fig. 5 where sand is used as a setting bed. These assemblies are not appropriate in vehicular applications, areas of large rainfall or in freezing climates where the pavement may heave when saturated.
Mortarless Brick Paving
Concrete Base
FIG. 5
Figure 6 shows a typical example of mortared brick paving over a reinforced concrete slab on grade. Mortared brick paving can be used for any type of pedestrian or vehicular traffic in both interior and exterior applications. This type of assembly is especially well-suited for heavy vehicular areas such as streets or parking lots and where surface drainage is necessary.
Mortared Brick Paving
Concrete Base
FIG. 6
DESIGN CONSIDERATIONS
Traffic
The weight and amount of traffic often dictate which paving system to use. The brick paving assembly must be capable of supporting traffic loads plus its own weight. The appropriate thickness of the subbase, base and brick paving units must be considered to adequately distribute vertical traffic loads. Three general classifications of traffic are light, medium and heavy, and should be considered when determining the subbase, base and brick paver thicknesses. The classifications of traffic are defined as follows:
Light Traffic. Residential pedestrian traffic only, such as on patios and walkways.
Medium Traffic. Commercial pedestrian traffic, such as on city sidewalks, building entrances and shopping malls. Light vehicular traffic, such as on residential driveways, commercial entranceways and parking lots.
Heavy Traffic. Heavy vehicular traffic, such as streets, crosswalks, loading docks and roads. The term heavy refers to both axle loads and frequency of loading.
Heavy vehicular traffic on grade will generally require rigid, semi-rigid, or thick flexible bases. Medium and light traffic may be supported on any of these or on suspended diaphragms.
Load Resistance
Vertical Loads. Vehicular traffic, pedestrian traffic and the weight of the paving assembly impose vertical loads upon the paving system. These loads are distributed to each pavement layer in a radiating manner. Each layer resists a proportion of the load depending on its strength and thickness. The most important aspect of designing the pavement to resist vertical loads is determining the appropriate thickness of the base. Inadequate base thickness will result in premature failure of the paving system, while excessive thickness will result in increased costs. For light and medium traffic applications, the minimum required thickness of each base material will normally govern. Pavements subjected to vehicular traffic, other than residential driveways, generally require design by an engineer.
Base Thickness The minimum thickness of an aggregate base depends primarily upon the strength of the subgrade. Typically, a flexible base of properly graded crushed stone or gravel should be a minimum thickness of 4 in. (100 mm). The minimum thickness of a reinforced concrete or an asphalt base in pedestrian and light vehicular traffic applications is 4 in. (100 mm), provided it bears on adequate subgrade. Concrete and asphalt bases usually require a subbase. Very heavy loading requires an increase in thickness for all types of bases. Additional information on base design is available from the appropriate reference [2,7].
Paving Surface Thickness- A mortarless brick paving surface can be supported on a flexible base, a semi-rigid base, a rigid base or a suspended diaphragm. Typically the base is designed to resist vertical loads independent of the