Page 55 - Design of Reinforced Masonry Structures

2.8 CHAPTER TWO

net cross-sectional area of the cored brick in
any plane parallel to the bearing surface be
not less than 75 percent of the gross cross-
sectional area measured in the same plane.
It is also required that no part of any hole be
less than ⁄ 4 in. from any edge of the brick
3
unit. Cores are only found in brick manu-
factured by extrusion process. Limits to the
amount of coring allowed in brick, the dis-
tance from a core to face, and the web thick-
ness where applicable, are specified by the
applicable ASTM Standard; a summary can
be found in Ref. [2.10].
Cored bricks offer many advantages.
They aid in manufacturing process and
shipping of brick. Coring results in lighter
bricks as compared to the solid bricks; con-
sequently, they are easier to handle during
placement. The reduced weight of cored
FIGURE 2.7 Placement of reinforcement in brick
bond beam units. (Courtesy: BIA.) bricks results in reduced shipping costs.
Cores reduce the amount of fuel necessary
to fire the units. Since bricks have to be laid
by hand, brick by brick, holes in bricks allow easy handling (lifting) and holding of the
brick by a bricklayer. Contrary to the perception that cored brick may be relatively weaker
(due to the reduced area) than the solid brick, the opposite is true. Cored bricks demonstrate
higher strengths due to more uniform drying and burning made possible by the presence of
holes. Cores also help develop better mechanical mortar bond as the mortar pressing into
the holes provides a good mechanical “key” [2.10, 2.13].

2.4.3 ASTM Classification of Brick Units

Clay building bricks are manufactured from clay or shale, and hardened by heat. Brick
units can be used to bear loads, or they can be used simply as nonload-bearing veneer to
give a weather-resistant skin or for architectural/aesthetic enhancements, the latter being
more common these days as load-bearing brick construction is not cost-effective. They are
commonly available in rectangular shapes of various sizes and colors. Building bricks must
conform to ASTM C62-01: Specification for Building Brick (Solid Masonry Units Made
from Clay or Shale) [2.12]. Hollow bricks, which are very similar in size and shape to hol-
low concrete units, must conform to the following ASTM Standards:

ASTM C216-02: Specification for Building Brick (Solid Masonry Units Made from
Clay or Shale) [2.14].
ASTM C652-01a: Specification for Hollow Brick (Solid Masonry Units Made from
Clay or Shale) [2.15].
In addition to building bricks and hollow bricks, there are other kinds of bricks used in
brick masonry construction for various applications. See Table 2.1 for a summary of vari-
ous types of bricks and the applicable ASTM Standards. A discussion on manufacturing,
classification, and selection of brick units can be found in Ref. 2.10.
As the names imply, the uses of bricks are similar to their respective ASTM designa-
tions. Various types of brick units listed in Table 2.1 are defined in the Glossary and are not