Page 95 - Masonry and Concrete

Understanding Masonry
94 CHAPTER FOUR

paving, may not always be durable enough
for paving in cold climates. Paving bricks
are manufactured to meet special needs
with high compressive strength, resistance
to abrasion, and low moisture absorption
to increase durability against winter freez-
SATURATED DRY ing and thawing cycles.
Paving brick that are designed to be
5
laid with mortar have the same 3- 8-in.
5
width 7- 8-in. length as modular brick.
Paving bricks that are designed to be laid
without mortar are a full 4 in. 8 in. so
that patterns will still lay out to a 4-in.
SURFACE SURFACE
module. Paving brick come in several
WET DRY
thicknesses, the most common of which
FIGURE 4-7 5
are 1- 8 in. for light traffic areas such as
1
Moisture content of brick. (from Technical Note 17C, patios and sidewalks, and 2- 4 in. for
Brick Industry Association, Reston, VA).
heavy traffic areas such as driveways and
streets (Figure 4-8).
4.2.4 Fire Brick

Fireplaces and barbecue pits have special requirements because of the
high temperatures to which the firebox brick are exposed. Special fire
brick are made from fire clay which has a much higher melting point
than ordinary clay or shale. Fire brick can tolerate long exposure to
high temperatures without cracking, decomposition, or distortion.
Fire brick are usually heavier, softer, and larger than ordinary brick.
They are laid with very thin joints of mortar made from fire-clay
instead of cement. Fire clay produces brick that are white or buff color.
The units must be 100% solid, with no cores or frogs.

4.3 Concrete Masonry Units

Concrete masonry units (CMUs) include both large block and smaller
brick size units. Concrete masonry units are made from cement, sand,
and crushed stone or gravel aggregate that is molded and cured at a
manufacturing plant. The basic ingredients are the same as those used
for cast-in-place concrete, except that the aggregate is smaller. Concrete

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