Glossary - Design and Control of Concrete Mixtures - page 331

Polymer-portland cement concrete —fresh portland
cement concrete to which a polymer is added for
improved durability and adhesion characteristics,
often used in overlays for bridge decks; also referred to
as polymer-modified concrete and latex-modified
concrete.
Popout —shallow depression in a concrete surface
resulting from the breaking away of pieces of concrete
due to internal pressure.
Portland blast-furnace slag cement —hydraulic
cement consisting of: (1) an intimately interground
mixture of portland-cement clinker and granulated
blast-furnace slag; (2) an intimate and uniform blend of
portland cement and fine granulated blast-furnace
slag; or (3) finely ground blast-furnace slag with or
without additions.
Portland cement —Calcium silicate hydraulic cement
produced by pulverizing portland-cement clinker, and
usually containing calcium sulfate and other
compounds. (See also Hydraulic cement. )
Portland cement plaster —a combination of portland
cement-based cementitious material(s) and aggregate
mixed with a suitable amount of water to form a plas-
tic mass that will adhere to a surface and harden,
preserving any form and texture imposed on it while
plastic. See also Stucco .
Portland-pozzolan cement —hydraulic cement con-
sisting of an intimate and uniform blend of portland
cement or portland blast-furnace slag cement and fine
pozzolan produced by intergrinding portland cement
clinker and pozzolan, by blending portland cement or
portland blast-furnace slag cement and finely divided
pozzolan, or a combination of intergrinding and blend-
ing, in which the amount of the pozzolan constituent is
within specified limits.
Pozzolan —siliceous or siliceous and aluminous mate-
rials, like fly ash or silica fume, which in itself possess
little or no cementitious value but which will, in finely
divided form and in the presence of moisture, chemi-
cally react with calcium hydroxide at ordinary temper-
atures to form compounds possessing cementitious
properties.
Precast concrete —concrete cast in forms in a
controlled environment and allowed to achieve a spec-
ified strength prior to placement on location.
Prestressed concrete —concrete in which compres-
sive stresses are induced by high-strength steel tendons
or bars in a concrete element before loads are applied to
the element which will balance the tensile stresses
imposed in the element during service. This may be
accomplished by the following: Post-tensioning—a
method of prestressing in which the tendons/bars are
tensioned after the concrete has hardened; or Pre-
tensioning—a method of prestressing in which the
tendons are tensioned before the concrete is placed.

Q
Quality control —actions taken by a producer or
contractor to provide control over what is being done
and what is being provided so that applicable stan-
dards of good practice for the work are followed.

R
Reactive-powder concrete —high-strength, low-water
and low-porosity concrete with high silica content and
aggregate particle sizes of less than 0.3 mm.
Ready-mixed concrete —concrete manufactured for
delivery to a location in a fresh state
Recycled concrete —hardened concrete that has been
processed for reuse, usually as an aggregate.
Reinforced concrete —concrete to which tensile bear-
ing materials such as steel rods or metal wires are
added for tensile strength.
Relative density —a ratio relating the mass of a
volume of material to that of water; also called specific
gravity.
Relative humidity —The ratio of the quantity of water
vapor actually present in the atmosphere to the amount
of water vapor present in a saturated atmosphere at a
given temperature, expressed as a percentage.
Retarder —an admixture that delays the setting and
hardening of concrete.
Roller-compacted concrete (RCC) —a zero slump
mix of aggregates, cementitious materials and water
that is consolidated by rolling with vibratory com-
pactors; typically used in the construction of dams, in-
dustrial pavements, storage and composting areas, and
as a component of composite pavements for highways
and streets.

S
Scaling —disintegration and flaking of a hardened
concrete surface, frequently due to repeated freeze-
thaw cycles and application of deicing chemicals.
Segregation —separation of the components (aggre-
gates and mortar) of fresh concrete, resulting in a
nonuniform mixture.
Self-compacting concrete —concrete of high worka-
bility that require little or no vibration or other
mechanical means of consolidation.
Set —the degree to which fresh concrete has lost its
plasticity and hardened.
Silica fume —very fine noncrystalline silica which is a
byproduct from the production of silicon and ferrosili-
con alloys in an electric arc furnace; used as a pozzolan
in concrete.
Shotcrete —mortar or small-aggregate concrete that is
conveyed by compressed air through a hose and
applied at high velocity to a surface. Also known as
gunite and sprayed concrete.
Shrinkage —decrease in either length or volume of a
material resulting from changes in moisture content,
temperature, or chemical changes.