Page 3 - Masonry and Concrete

Introduction to Concrete and Masonry
2 CHAPTER ONE

1.1 Characteristics and Performance

Concrete is a fluid mixture of cement, aggregates, and water which can
be formed into different shapes and cures to a hard and durable con-
struction material. Masonry is construction of natural building stone
or manufactured units such as brick or concrete block.
All building materials expand and contract. Concrete and other
cement-based products shrink permanently, and clay products expand
permanently with changes in moisture content. Both materials (as well
as wood, metal, glass, and plastics) expand and contract reversibly
with changes in temperature. Since concrete and masonry are brittle,
if construction does not accommodate this expansion and contraction,
cracking and water penetration can result. Flexible anchorage and the
installation of control joints in concrete and concrete masonry and
expansion joints in clay masonry allow this natural expansion and
contraction to occur without damage to the construction.
Concrete can be used as a structural and a finish material in slabs,
walls, paving, and retaining walls. Masonry can be used as a structural
system, as a veneer, or as a paving system and can be used to build fire-
places and retaining walls. Concrete and masonry are strong in com-
pression but require the incorporation of reinforcing steel to resist
tensile and bending stresses. Masonry veneers can be constructed over
many types of structural frames and backing walls. Concrete and
masonry also provide fire resistance, energy efficiency, and durability.

Fire Resistance: Concrete and masonry are noncombustible—they
will not burn. This is a higher level of protection than mere fire resis-
tance. Wood can be injected with chemicals to make it resistant to fire
damage for a longer period of time than untreated wood, but ulti-
mately wood becomes fuel for the fire. Steel is noncombustible, but it
softens and bends when subjected to the high heat of a fire. In com-
mercial construction, steel structural members must be protected from
fire by sprayed-on mineral coatings, layers of gypsum board, plaster, or
masonry. The highest level of protection and the highest fire protec-
tion ratings are associated with concrete and masonry.
Insurance companies recognize the value of noncombustible con-
struction through reduced fire insurance premiums. Newsweek magazine
published a photo after the wildfires in Oakland, California, several years

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