Page 88 - Masonry and Concrete

Understanding Masonry
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UNDERSTANDING MASONRY

4.2 Brick

Brick can be made of several different materials, but the most common
type of brick is made from ordinary clay soil. Clay brick is the oldest
manufactured building material in the world, and it is still one of the
most widely used. Sun-dried mud bricks are estimated to have been in
use for about 10,000 years, and fired bricks since about 3,000 B.C. Sun-
dried bricks are a traditional residential construction material in dry
climates and are still used in many countries. The adobe construction
of the Southwestern United States is made of sun-dried clay brick pro-
tected from the weather by a stucco coating. More typically, modern
clay brick is fired at over 2,000°F in a large kiln to produce units that
are very dense, hard, and durable. The color of the clay determines the
color of the brick, and more than one clay can be combined to produce
a variety of colors. Brick textures vary depending on the molding and
forming process. Most brick are shaped by extruding wet clay through
a die and slicing it to the appropriate size. Extruded brick may have
holes cored through the middle which makes them lighter in weight
and allows mortar to physically interlock with the brick. Even though
they may contain core holes, if the cores account for 25% or less of the
cross sectional area of the brick, the units are still considered to be
solid. By this definition, most bricks are considered solid masonry
units. Molded bricks are actually solid and do not have core holes, but
they may have an indentation called a frog in one or both bed surfaces.
When building codes make reference to solid masonry, they are refer-
ring to either masonry constructed of solid units (i.e., brick), or of
solidly grouted hollow units such as concrete block.

4.2.1 Brick Sizes, Shapes, and Colors
Brick are rectangular in shape but come in many different sizes. The
easiest size to work with is called modular brick because its height and
length are based on a 4-in. module. The measured dimensions of a
masonry unit are called the actual dimensions, and the dimensions of
a masonry unit plus one mortar joint are called the nominal dimen-
5
sions. The actual dimensions of a modular brick are 3- 8 in. wide 2-
5
1 4 in. high 7- 8 in. long. The nominal length of one modular brick
3
plus one 8-in. mortar joint is 8 in. Three bricks laid one on top the
other with three mortar joints is also equal to 8 in. If the height and

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