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Common Terms
Admixture—A
material other than water, aggregates, cement or fiber reinforcement,
used as an ingredient of concrete and added to the concrete immediately
before or during mixing.
Aggregate—A granular materials
such as sand, gravel, or crushed stone that along with portland
cement and water is the primary ingredient in concrete.
Air-entrained concrete—Concrete
in which air in the forum of minute, disconnected bubbles has been
intentionally introduced into the mixture during the mixing process.
These air bubbles leave pockets where water can expand when it freezes
without causing damage to the concrete. Most concrete mixtures need
between five to eight percent entrained air.
Bleed water—Small amounts
of water from the concrete mix that sometimes flow to the surface
of concrete because of the settling of solid materials in concrete.
Cement—Modern portland cement
is the product of high temperature conversion of finely ground materials—often
basic blends of limestone, clay and shale—containing four
key elements: calcium, silica, aluminum, and iron. Cement plants
are situated at quarries with rocks bearing some or all of these
elements.
Concrete—A mixture in which
a paste of portland cement and water binds aggregates into a rocklike
mass that hardens through the chemical action of hydration. Like
cement, concrete is produced from local resources, with many grades
of fine and coarse aggregates available from region to region to
meet standard and specific mix needs.
Consistency—The relative
mobility or the ability of freshly mixed concrete to flow.
Curing—Maintaining a satisfactory
moisture concrete and a favorable temperature in freshly laid concrete.
Curing goes beyond setting; it should last for at least seven days.
Fiber reinforcement—Concrete
containing dispersed, randomly oriented fibers to improve certain
properties of concrete.
Finishing—Leveling, smoothing,
consolidating, and otherwise treating surfaces of fresh or recently
placed concrete to produce a desired appearance and service.
Flatwork—A general term
applicable to concrete floors and slabs that require finishing operations
Fly ash—The fine ash resulting
from burning coal in electric utility plants, used as a mineral
admixture in cement manufacturing and concrete.
Hydration—The chemical
reaction between cement and water that makes wet, fresh concrete
harden.
Joint—A physical
separation in concrete, whether precast or cast-in-place, including
cracks if intentionally made to occur at specified locations; also
the region where structural members intersect, such as a beam-column
joint.
Plastic concrete—Freshly
mixed concrete that is pliable and capable of being molded or shaped.
PSI (pounds per square
inch)—A standard measurement of strength used for many building
materials, including concrete. Measurement tells how much pressure
the material can stand on a square inch before breaking. MPa (mega
Pascal) is the metric unit of measure.
R-value—A measure of resistance
that a wall unit offers to the flow of heat. The more slowly heat
passes through, the higher the R-value.
Sieve—A wire mesh screen
with square openings used to determine the size of aggregates.
Slump—A measure of the
consistency of freshly mixed concrete in which a conical metal mold
is first filled with fresh concrete, inverted, and then lifted off
the concrete. The distance the concrete settles measure to the nearest
¼-inch is the slump value. A high slump value is indicative
of a wet or fluid concrete.
Water-cement ratio—The
ratio of the weight of water to the weight of cement in a concrete
mixture.
Workability—The ease of
placing, consolidating, and finishing freshly mixed concrete.
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