Page 82 - Design of Reinforced Masonry Structures

MASONRY UNITS: APPLICATIONS, TYPES, SIZES, AND CLASSIFICATION 2.35

FIGURE 2.32 A slump block wall. (Courtesy: FIGURE 2.33 A wall with split-face concrete
PCA.) blocks. (Courtesy: PCA.)

2.6.10 Second-Hand Concrete Masonry Units
Discussion of second-hand clay masonry units presented in Section 2.5.8 applies to con-
crete masonry also.

2.6.11 Sound Absorbing Properties of Concrete Blocks
Concrete blocks with open exterior texture have excellent sound absorbing property. It is
known that, upon striking a surface, sound waves are partly absorbed, partly reflected, and
partly transmitted in varying amounts, depending upon the surface characteristics of concrete
blocks. Surfaces which are smooth and dense, such as plaster and glass, reportedly, absorb
only about 3 percent of the sound striking it. On the other hand, ordinary concrete blocks
with rough surface characteristics can absorb between 18 and 68 percent of the sound that
strikes it. In modern highway construction, concrete block sound barrier walls on the sides of
the roadway are quite common. Design of sound barrier walls is discussed in Chap. 6.

2.7 BONDS AND PATTERNS IN MASONRY WORK

2.7.1 Bonds
The word “bond” is commonly used in the context of masonry design and construction.
It is frequently references in building codes and specifications. Three kinds of bond are
recognized [2.48]:
1. Structural bond: It refers to the method by which individual units are tied together so
that the entire assembly acts integrally as a single structural unit.
2. Pattern bond: It refers to the pattern formed by the masonry units and the mortar joints
on the face of a wall. The bond pattern may be the result of type of the structural bond
used, or it may be purely decorative and unrelated to the structural bond.
3. Mortar bond: It refers to the adhesion of mortar to the masonry units or to reinforcement.