Page 33 - Design of Reinforced Masonry Structures

1.2 CHAPTER ONE

Masonry construction is accomplished by laying masonry units by hand. As such, they can
be laid in a variety of arrangements. Units of different sizes can be used in the same construc-
tion. For example, various-sized rectangular units having sawed, dressed, or squared surfaces,
properly bonded and laid in mortar, can be used for wall construction, an arrangement of units
referred to as ashlar masonry. The same masonry can be laid in courses of equal or different
heights and is then referred to as coursed ashlar masonry. The term random ashlar is used to
describe ashlar masonry laid in courses of stones without continuous joints and laid up without
drawn patterns. Masonry units can be solid or hollow. Solid masonry consists of masonry units
that are solid (i.e., without any voids) and laid contiguously with the joints between the units
filled with mortar. Various types of units and their arrangements are described in Chap. 2.

1.3 A BRIEF HISTORY OF MASONRY
CONSTRUCTION

The history of masonry construction can be considered as the beginning of the history of civil
engineering. Naturally availability of stones has been responsible for masonry being the oldest
building material known to humans. The first use of stones for any form of construction was
random rubble dry masonry, a form of construction in which stones of various sizes were ran-
domly stacked on top of each other to build a wall without using any mortar (hence, the term
dry masonry). Smaller stones were used to fill the voids between the larger stones; mud was
used sometimes to bond the stones together. This form of construction is still in use today in
some third world countries, used mainly for building temporary wall fences for rural farm areas
and land, and for retaining walls. A variation of random rubble dry masonry uses horizontal and
vertical bands of lime or cement mortar at regular intervals in otherwise dry wall. Unreinforced
masonry has been used for centuries throughout the world, and is still in use today for construc-
tion of buildings and small dams. These structures typically use masonry fully grouted in cement
or lime mortar, with stones of approved geologic classification, size, and quality. Voids between
the large grouted stones are packed with small stones and mortar. The exterior surfaces of these
structures may have finish with coursed or uncoursed masonry with flush or pointed joints.
Soon to follow the use of natural stone as a building material was the man-made build-
ing material called brick. The art of brick building is reported to be some 10 to 12 millennia
old. The earliest type of brick, called “adobe,” evolved as sun-dried lumps of mud or clay,
which later developed into a preformed modular masonry unit of sun-dried mud. Sun-dried
bricks are known to have been widely used in Babylon, Egypt, Spain, and South America.
These bricks were made by pressing mud or clay into small lumps [1.3]. An excellent docu-
mentation of adobe brick wall construction has been given by McHenry [1.4].
The earliest molded brick was developed, supposedly in Mesopotamia, about 5000 B.C.
However, it was the invention of the fired brick about 3500 B.C. that revolutionized struc-

tural construction, and gave birth to permanent structures all over the world. Firing gave the
brick the quality of resilience which the mud bricks lacked–its most significant aspect was
the simplicity with which bricks could be easily shaped and used for potentially endless
exact repetitions of decorative patterns. Glazing, a subsequent development, made it pos-
sible to provide rich ornament in brick as well to produce brick in vivid colors.
Brick continues to be used today as one of the most versatile building materials, with a
rich, enduring, and illustrious history. Some of the most magnificent and remarkable brick
structures built in the past stand as testimony to the architectural elegance and potential
of brick as a structural material. These include the Hanging Gardens, one of the Seven
Wonders of the World; the Great Wall of China, the largest man-made object on the earth;
the Hagia Sophia, one of the most beautiful churches ever built; the great medieval castle
of Malbork, Poland, which is the size of a small town; the 2000 temples in Pagan, Burma,