Glossary - Design and Control of Concrete Mixtures - page 328

Blended hydraulic cement —cement containing
combinations of portland cement, pozzolans, slag,
and/or other hydraulic cement.
Bulking —increase in volume of a quantity of sand
when in a moist condition compared to its volume
when in a dry state.

Compressive strength —maximum resistance that a
concrete, mortar, or grout specimen will sustain when
loaded axially in compression in a testing machine at a
specified rate; usually expressed as force per unit of
cross sectional area, such as megapascals (MPa) or
pounds per square inch (psi).
Concrete —mixture of binding materials and coarse
and fine aggregates. Portland cement and water are
commonly used as the binding medium for normal
concrete mixtures, but may also contain pozzolans,
slag, and/or chemical admixtures.
Consistency —relative mobility or ability of freshly
mixed concrete, mortar, or grout to flow. (See also
Slump and Workability. )
Construction joint —-a stopping place in the process
of construction. A true construction joint allows for
bond between new concrete and existing concrete and
permits no movement. In structural applications their
location must be determined by the structural engineer.
In slab on grade applications, construction joints are
often located at contraction (control) joint locations and
are constructed to allow movement and perform as
contraction joints.
Contraction joint —weakened plane to control crack-
ing due to volume change in a concrete structure. Joint
may be grooved, sawed, or formed. Also known as a
“Control joint.”
Corrosion —deterioration of metal by chemical, elec-
trochemical, or electrolytic reaction.
Creep —time-dependent deformation of concrete, or of
any material, due to a sustained load.
Curing —process of maintaining freshly placed con-
crete mortar, grout, or plaster moist and at a favorable
temperature for a suitable period of time during its
early stages so that the desired properties of the mate-
rial can develop. Curing assures satisfactory hydration
and hardening of the cementitious materials.

C
Calcined clay —clay heated to high temperature to
alter its physical properties for use as a pozzolan or
cementing material in concrete.
Calcined shale —shale heated to high temperature to
alter its physical properties for use as a pozzolan or
cementing material in concrete.
Carbonation —reaction between carbon dioxide and a
hydroxide or oxide to form a carbonate.
Cellular concrete —-high air content or high void
ratio concrete resulting in low density.
Cement —see Portland cement and Hydraulic cement.
Cement paste —constituent of concrete, mortar, grout,
and plaster consisting of cement and water.
Cementitious material (cementing material) —any
material having cementing properties or contributing
to the formation of hydrated calcium silicate
compounds. When proportioning concrete, the follow-
ing are considered cementitious materials: portland ce-
ment, blended hydraulic cement, fly ash, ground
granulated blast-furnace slag, silica fume, calcined clay,
metakaolin, calcined shale, and rice husk ash.
Chemical admixture —see Admixture.
Chemical bond —bond between materials resulting
from cohesion and adhesion developed by chemical
reaction.
Clinker —end product of a portland cement kiln; raw
cementitious material prior to grinding
Chloride (attack) —chemical compounds containing
chloride ions, which promote the corrosion of steel
reinforcement. Chloride deicing chemicals are primary
sources.
Coarse aggregate —natural gravel, crushed stone, or
iron blast-furnace slag, usually larger than 5 mm (0.2
in.) and commonly ranging in size between 9.5 mm and
37.5 mm ( 3 ⁄ 8 in. to 1 1 ⁄ 2 in.).
Cohesion —mutual attraction by which elements of a
substance are held together.
Colored concrete —concrete containing white cement
and/or mineral oxide pigments to produce colors other
than the normal gray hue of traditional gray cement
concrete.
Compaction —process of inducing a closer arrange-
ment of the solid particles in freshly mixed and placed
concrete, mortar, or grout by reduction of voids, usually
by vibration, tamping, rodding, puddling, or a combi-
nation of these techniques. Also called consolidation.

D
Dampproofing —treatment of concrete, mortar, grout,
or plaster to retard the passage or absorption of water,
or water vapor.
Density —mass per unit volume; the weight per unit
volume in air, expressed, for example, in kg/m 3
(lb/ft 3 ).
Durability —ability of portland cement concrete,
mortar, grout, or plaster to resist weathering action and
other conditions of service, such as chemical attack,
freezing and thawing, and abrasion.

E
Early stiffening —rapidly developing rigidity in
freshly mixed hydraulic cement paste, mortar, grout,
plaster, or concrete.
Entrapped air —irregularly shaped, unintentional air
voids in fresh or hardened concrete 1 mm or larger in