Page 301 - Masonry and Concrete

Paving

300 CHAPTER EIGHT

Rigid paving systems with mortared joints create a formal look while
flexible systems with sanded joints are more rustic in appearance. One
may be more appropriate than the other on any given project, depend-
ing on the style of the house and the type of landscaping that is
planned. Concrete masonry pavers are designed for and typically used
in flexible paving systems. Brick and natural stone are used in both
rigid and flexible paving systems.
Rigid masonry paving is laid on a mortar setting bed over a rein-
forced concrete base. The base may be either a new or an existing con-
crete slab. A Type M masonry mortar should be used for both the setting
bed and the joints in outdoor paving exposed to the weather. Some
authorities believe that an air-entrained mortar can improve freeze-thaw
resistance in masonry paving in the same way that air-entrained con-
crete improves the winter durability of concrete paving. Use either an
air-entrained portland cement mixed with mason’s lime or an air-
entrained masonry cement in the proportions recommended in Chapter
1
4 for a Type M mix. The mortar setting bed should be about 2 in. thick.
Flexible masonry paving systems for residential sidewalks and
patios are typically laid on a sand bed placed directly over an undis-
turbed soil subgrade. For driveways, a gravel base must first be installed
over the subgrade to provide additional stability and moisture protec-
tion. The sand layer acts as a leveling bed which compensates for irreg-
ularities in the soil or gravel surface and provides a smooth substrate for
placement of the units. A sheet membrane must be installed to prevent
sand from settling into a gravel base. Sheet membranes are also installed
in flexible paving systems to discourage weed growth. Roofing felt,
polyethylene film, and special weedblock landscaping fabrics are all
suitable because they are moisture- and rot-resistant. Pavers are gener-
ally butted together with only the minimal spacing between adjacent
units caused by irregularities of size and shape. The joints are swept full
of dry sand to fill between units. Even though mortarless masonry
paving is flexible and has the ability to move slightly to accommodate
expansion and contraction, it is recommended that expansion joints be
placed adjacent to fixed objects such as curbs and walls.

8.3.1 Brick Paving

Modular paving bricks that are designed to be laid with mortar have
5
5
the same 3- 8 in.- 7- 8 in. face dimensions as ordinary modular wall

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