Masonry Magazine April 1995 Page. 22
CONCRETE SLAB
MORTARED BRICK PAVING
EXPANSION JOINT, TYP.
(a)
COMPACTED GRAVEL
MORTARED BRICK PAVING
EXPANSION JOINT
CONCRETE SLAB
COMPACTED GRAVEL
COMPACTED SUBGRADE
(b)
Stair and Ramp Sections
FIG. 6
slips and falls. Brick usually has an adequate slip resistance, with higher coefficient of friction values achieved when a rough textured brick is used.
SELECTION OF MATERIALS
Pavements can be subjected to severe weather and abrasion; therefore, the materials used to construct them must be of superior quality. Most of the materials in a pavement must conform to ASTM standards. Following are recommendations for the selection of paving materials. Additional information on material selection can be found in Technical Notes 14 Series.
Brick Pavers
Pavers must be able to withstand the weather and the abrasion of pedestrian traffic. Pavers should conform to the requirements of ASTM C 902 Specification for Pedestrian and Light Traffic Paving Brick. Units conforming to ASTM C 1272 Specification for Heavy Vehicular Paving Brick may be used, but are usually not necessary for most landscape applications, unless heavy vehicular traffic is expected. Heavy vehicular traffic is composed of high volumes of heavy vehicles on a pavement. Two of the more critical requirements of ASTM C 902, durability and abrasion, are discussed below. Other requirements, such as dimensional tolerances, chippage and warpage should also be considered.
Durability. The resistance of pavers to weathering is determined by the Class of the paver. The Class of the paver is based on the durability of the unit and is determined by compressive strength, cold water absorption and saturation coefficient of the unit. Class SX pavers are intended for use where the paver may be frozen while saturated with water. In exterior applications where freezing is not present, pavers should conform to Class MX or SX. Class NX pavers are acceptable for interior use where they are protected from freezing when wet. Alternate means of assessing durability of brick pavers are addressed in ASTM C 902 and Technical Notes 14A Revised.
Abrasion Resistance. Pavers must be able to resist the abrasive action of traffic. ASTM C 902 includes three abrasion classifications of pavers; Types I, II and III. Type I pavers are appropriate for areas receiving extensive abrasion, such as commercial driveways and entrances. Type II pavers are intended for exterior walkways and floors in restaurants and stores. Type III pavers are used for residential floors and patios. The paver Type is determined by its abrasion index, which is calculated by dividing the cold water absorption by the compressive strength and multiplying by 100. The resistance to abrasion can also be determined by a laboratory test, as outlined in ASTM C 902.
Setting Bed Materials
The setting bed, placed between the base and the brick pavers, functions as a leveling course for slight irregularities in the base and units. Setting bed materials include sand, mortar, asphalt and building felt.
Sand. Sand used as a setting bed should be a washed, well-graded angular sand with a maximum particle sized of in. (4.8 mm). Sand should conform to ASTM C 33 Specification for Concrete Aggregates, usually referred to as concrete sand. Mason's sand can also be used as the setting bed material when the thickness of the setting bed is less than 1 in. (25 mm). Mason's sand should conform to ASTM C 144 Specification for Aggregates for Masonry Mortar. The thickness of the sand setting bed should be between % in. and 2 in. (13 mm and 50 mm).
Mortar. Mortar setting beds are used in mortared brick paving applications. Mortar should conform to ASTM C 270 Specification for Mortar for Unit Masonry or ANSI A118.4 Specification for Latex-Portland Cement Mortar, when a latex additive is used. For exterior mortared brick pavements. Type M mortar is preferred. Type M portland cement-lime mortar consists of 1 part portland cement, ½ part hydrated lime and 3% parts sand. Type S mortar can be used alternately. In severe freeze/thaw environments, mortars with better freeze/thaw resistance should be used. Two mortar properties that greatly influence freeze/thaw resistance