Introduction
The
people involved in the cement or concrete industries, either in its
manufacture, use, or application is so broad that the information
contained should be understood by everyone.
Whether the reader is an architect, engineer, contractor, worker,
supplier of materials, or any one of the many other people involved in the
concrete industry, these definitions have been designed to be as clear,
basic, and as informative as possible.
It is not the intent of this glossary to cover every term in every
classification, but those which are most used or misused, or abused.
AAC
- Autoclaved Aerated Concrete Exceptionally
lightweight precast concrete with high thermal qualities and fire
resistence. Suitable for
cutting with ordinary hand tools. Mix
design is composed of portland cement, sand or siliceous material, lime,
gypsum, finely powdered aluminum, and water.
Initial mix is a combination of portland cement, sand, lime and
gypsum to produce a slurry. Finely
powdered aluminum mixed into a paste is added prior to placement into
large, rail-like forms. The
finely powdered aluminum reacts with the alkaline components of the cement
and lime to produce hydrogen gas, which increases the volume approximately
five times producing a uniformly, dispersed cellular structure.
Units are cut to required shape.
Units are placed in an autoclave, an enclosed pressurized chamber,
and steam cured at 3500 F.
Approximately 80% of the ultimate volume consists of air voids.
Abrasion
Resistance Resistance
of a surface of being worn away by friction or rubbing process.
Absolute
Volume
The volume of an ingredient in its solid state, without voids between
individual pieces or particles, in the case of fluids, the cubic content
occupied. In concrete, the actual volume occupied by the different
ingredients determined by dividing the weight of each ingredient pounds,
by ifs specific gravity, times the weight of one cubic foot of water in
pounds. Example: Absolute Volume of one sack of cement equals:
94 ÷
(3.15X62.4) = 0.478 cubic feet
Absorbed
Moisture
Moisture which is mechanically held in a material.
In aggregates, that water which is not available to become part of
the mixing water is designated "absorbed" water.
Absorption
The process by which water is absorbed.
The amount of water absorbed under specific conditions, usually
expressed as percentage of the dry weight of the material.
Accelerator
An admixture which, when added to concrete, mortar, or grout, increases
the rate of hydration of the hydraulic cement, shortens the time of set
and increases the rate of hardening or strength development,
Adiabatic
Curing
The maintenance of ambient conditions during the setting and hardening of
concrete so that heat is neither lost nor gained from the surroundings of
the concrete.
Admixture
A material other than water, aggregates, and portland cement that is used
as an ingredient of concrete, and is added to the batch immediately before
or during the mixing operation.
Adsorption
Water
Water held on surfaces in a material by either physical and/or
chemical forces.
Air
Content
The amount of entrained or entrapped air in concrete or mortar, exclusive
of pore space in aggregate particles, usually expressed as a percentage of
total volume of concrete or mortar.
Air
Entraining Agent
An addition for hydraulic cement, or an admixture for concrete or mortar
which entrains air in the form of minute bubbles in the concrete or mortar
during mixing.
Alkali-Aggregate
Reaction
Older terminology for Alkali-Silica Reactivity (ASR).
ASR
- Alkali-Silica Reactivity The
reaction of aggregates, which contain some form of silica or carbonates
with sodium oxides or potassium oxides in cement, particularly in warm,
moist climates or environments, causing expansion, cracking or popouts in
concrete.
Aluminous
Cement A
hydraulic cement in which the principal constituents are calcium
aluminates, instead of calcium silicates which comprise the major
ingredients of portland cement. (See calcium aluminate cement)
Autoclave
A chamber in which an environment of steam and high pressure is produced.
Used in curing of concrete products and in the testing of hydraulic
cement for soundness.
Bag
(of cement) (See Sack)
Barrel
(of cement) A unit of weight for cement: 376 Ibs net, equivalent to 4 US
bags of portland cement. The designation presently used is tons of cement.
Blaine
Fineness
The fineness of granular materials such as cement and pozzolan, expressed
as total surface area in square centimeters per gram, determined by the
Blaine air-permeability apparatus and procedure.
Blast
Furnace Slag
A non-metallic waste product developed in the manufacture of pig iron,
consisting basically of a mixture of lime, silica and alumina, the same
oxides that make up portland cement, but not in the same proportions or
forms. It is used both in the
manufacture of portland blast furnace slag cement and as an aggregate for
lightweight concrete.
Bleeding,
Bleed Water
A form of segregation in which some of the water in a mix tends to rise to
the surface of freshly placed concrete.
Known also as water gain.
Bond
Adhesion of concrete or mortar to reinforcement, or to other surfaces.
The adhesion of cement paste to aggregate.
Bush-hammer
A tool having a serrated face, as rows of pyramidal points, used to
develop an architectural finish for concrete surfaces.
Calcareous
Containing calcium carbonate or, less generally, containing the element
calcium.
Calcine
To alter composition or physical state by heating to a specific
temperature for a specific length of time.
Calcium
Aluminate Cement
The product obtained by pulverizing clinker consisting essentially of
hydraulic calcium aluminates resulting from fusing or sintering a suitable
proportioned mixture of aluminous and calcareous materials.
Capillarity
A
wick-like action whereby a liquid will migrate vertically through
material, in a upward direction; as oil in a lamp travels upward through
the wick,
Capillary
Space
In cement paste, any space not occupied by anhydrous cement or cement gel.
Air bubbles, whether entrained or entrapped, are not considered as
part of the cement paste.
Carbonation
1) Reaction between the products of portland cement (soluble calcium
hydroxides), water and carbon dioxide to produce insoluble calcium
carbonate (efflorescence). 2)
Soft white, chalky surface dusting of freshly placed, unhardened concrete
caused by carbon dioxide from unvented heaters or gasoline powered
equipment in an enclosed space. 3)
Carbonated, dense, impermeable to absorption, top layer of the surface of
concrete caused by surface reaction to carbon dioxide.
This carbonated layer becomes denser and deeper over a period of
time. 4) Reaction with carbon dioxide which produces a slight
shrinkage in concrete. Improves
chemical stability. Concrete
masonry units during manufacturing may be deliberately exposed to carbon
dioxide after reaching 80% strength to induce carbonation shrinkage to
make the units more dimensionally stable.
Future drying shrinkage is reduced by as much as 30%.
Cellular
Concrete
A lightweight product consisting of portland cement, cement-pozzolan,
cement sand, lime-pozzolan, or lime-sand pastes, or pastes containing
blends of these ingredients and having a homogenous void or cell
structure, attained with gas forming chemicals or foaming agents. For
cellular concretes, containing binder ingredients other than or in
addition to portland cement, autoclave curing is usually employed.
Cement,
Portland (ASTM C150) A
powdery substance made by burning, at a high temperature, a mixture of
clay and limestone producing lumps called “clinkers” which are ground
into a fine powder consisting of hydraulic calcium silicates.
For non-portland cements, see aluminous cement.
Cement
Content
A quantity of cement contained in a unit volume of concrete or mortar,
ordinarily expressed as pounds, barrels, or bags per cubic yard.
Cement
Gel
The colloidal gel (glue like) material that makes up the major portion of
the porous mass of which hydrated cement paste is composed.
Cementitious
Having cement-like, cementing, or bonding type properties.
Material or substance producing bonding properties or cement-like
materials.
Chair(s)
In
concrete formwork, the support for the reinforcing steel.
Change
of State The
process whereby liquid is heated to the point of evaporation changing the
liquid into a gas the condensation of a gas on a cooler surface returning
it from gaseous to liquid form.
Coarse
Aggregate
Naturally occurring, processed or manufactured,
inorganic particles in prescribed gradation or size range, the
smallest size of which will
be retained on the No. 4 (4.76 mm) sieve.
Coefficient
of Thermal Expansion
Change in unit length per degree change of temperature.
Cold
Joint
A visible lineation which forms when the placement of concrete is delayed.
The concrete in place hardens prior to the next placement of concrete
against it.
Colloidal
A gel-like mass which does not allow the transfer of ions
Compressive
Strength
The measured resistance of a concrete or mortar specimen to axial loading
expressed as pounds per square inch {psi) of cross-sectional area. The
maximum compressive stress which material, portland cement, concrete, or
grout is capable of sustaining.
Concrete
A composite material which consists essentially of a binding medium,
within which are embedded particles or fragments of a relative
inert filler in portland cement concrete, the binder is a mixture of
portland cement, possibly additional cementitious materials such as fly
ash and water; the filler may be any of a wide variety of natural or
artificial, fine and coarse aggregates; and in some instances, an
admixture.
Condensation
When
a moisture laden gas comes in contact with a cooler surface a change of
state from gaseous to liquid occurs.
Consistency
The degree of plasticity of fresh concrete or mortar The normal measure of
consistency is slump for concrete and flow for mortar.
Consolidation
- Compaction usually accomplished by vibration of newly placed concrete to
minimum practical volume, to
mold it within form shapes
and around embedded parts and
reinforcement, and to eliminate voids other than entrained air.
Construction
Joint
The contact between the placed concrete and concrete surfaces, against or
upon which concrete is to be placed and to which new concrete is to
adhere, that has become so rigid that the new concrete cannot be
incorporated integrally by vibration with that previously placed. Unformed
construction joints are horizontally placed or nearly so.
Cure
Method of maintaining sufficient internal humidity and proper temperature
for freshly placed concrete to assure proper hydration of the cement, and
proper hardening of the concrete.
Density
Weight per unit volume.
Dispersing
Agent
An admixture capable of increasing the fluidity of pastes, mortars, or
concretes by reduction of interparticle attraction.
Dry
Rodded Weight
The weight of dry aggregate rodded into a cylindrical container of
diameter approximately equal to the height, each of 3 layers rodded 25
times, and the excess aggregate struck off level with the top of the
container
Drying
Shrinkage
A decrease in the volume of concrete upon drying.
Durability
The ability of concrete to resist weathering action, chemical attack, and
abrasion.
Efflorescence
A crystalline deposit of salts which leach from the concrete as soluble
calcium hydroxides and within a short period of time will combine with the
atmospheric carbon dioxide to form insoluble calcium carbonates, usually
white in color, appearing on the surfaces of masonry, stucco or concrete.
Elastic
Shortening
The shortening of a member in pre-stressed concrete which occurs on the
application of forces induced by prestressing.
Entrained
Air
(See air entrainment) Microscopic air bubbles intentionally incorporated
in mortar or concrete, to improve workability and durability (usually
imparting a higher degree of resistance to freezing and thawing).
Entrapped
Air
Air in concrete which is not purposely en-trained, Entrapped air bubbles
are normally much larger and more irregular than entrained air bubbles.
False
Set
The rapid development of rigidity in a mixed portland cement paste,
mortar, or concrete without the evolution of much heat. This rigidity can
be dispelled and plasticity regained by further mixing without addition of
water. Premature stiffening,
and rubber set are terms referring to the same phenomenon, but false set
is the preferred term.
Fine
Aggregate
Aggregate passing the 3/8-in. sieve and almost entirely passing the
No.4(4.76 mm) sieve and predominantly retained on the No. 200 (74 micron)
sieve(ASTM125).
Fineness
Modulus
An index of fineness or coarseness of an aggregate sample. An empirical
factor determined by adding total percentages of an aggregate sample
retained on each of a specified series of sieves, and dividing the sum by
100. Note: US Standard sieve
sizes are used: No. 100, No.50, No. 30, No. 16, No. 8, and No. 4, and 3/8
in., 3/4 in., I in., 2 in., 3
in., and 6 in.
Flash
Set
The rapid development of rigidity in a mixed portland cement paste, mortar
or concrete usually with the evolution of considerable heat, which
rigidity cannot be dispelled nor can the plasticity be regained by further
mixing without addition of water Also referred to as quick set or grab
set.
Flexural
Strength
A property of a solid that indicates its ability to withstand bending.
Fly
Ash
The finely divided residue that results from the combustion of ground or
powdered coal, transported from the firebox through the boiler by flue
gases.
Foam
Concrete
(See Cellular concrete)
Gap-graded
Aggregate
Aggregate containing particles of both large and small sizes, in which
particles of certain intermediate sizes are wholly or substantially
absent.
Gas
Concrete
(See cellular concrete)
GFRC
-
Glass Fiber Reinforced Concrete
Concrete panels, usually architectural designs, reinforced with a high
zirconia (16% minimum), alkali-resistant glass fiber.
Optimum glass fiber content of 5% by weight.
Lower fiber content results in lower early ultimate strengths,
higher fiber content can produce composite compaction and consolidation
difficulties.
Gillmore
Needle
A device used in determining time of setting of hydraulic cement,
described in ASTM 0 266. Gradation The sizing of granular materials; for
concrete materials, usually expressed in terms of cumulative percentages
larger or smaller than each of a series of sieve openings or the
percentages between certain ranges of sieve openings.
Grout
A fluid mixture of (1) cement, sand, and water or (2) cement and water:
the hardened equivalent of such mixtures.
Gunite
A term sometimes used to designate dry-mix shotcrete.
Heat
of Hydration
The quantity of heat expressed in calories per gram, evolved upon complete
hydration of portland cement at a given temperature.
Holding
Period Period In the
manufacture of concrete products, the period between completion of casting
and the introduction of additional heat or the steam curing period.
HRM
High
Reactivity Metakaolin. Refined
form of an ASTM C618, Class N (natural) pozzolan. A high performance,
mineral admixture, similar in performance to silica fume, additionally
comparable in cost. Pure
white powdered in form will, not
effect the natural color or darken concrete as silica fume does. Suitable
for high-performance color matching in
architectural concrete. Dosage
at 5% to 10%, of cement by
weight. No bleed water,
better finishability, more creamy, cleanup is easier with slightly higher
28 day strengths and 25% - 35% less plasticizer is required than silica
fume.
Process:
Produced
by heating a purified kaolinite clay to a specific high temperature to
alter the physical composition (calcined).
Through a carefully controlled refining process,
impurities are removed producing an almost 100% reactive,
pure white, pozzolanic powder, very evenly distributed in particle
size and results in a mineral admixture which is consistent in appearance
and performance from lot to lot.
Hydration
Formation of a compound by the union of water with some other substance.
In concrete it is the chemical reaction between water and the cement.
A concrete slab needs to completely hydrate prior to the
application of paints, coatings, and flooring materials.
Hydraulic
Cement
A cement that is capable of setting and hardening under water due to
interaction of water and the constituents of the cement (ASTM 219).
Hydrogenesis
Another
term for condensation. The term is especially applied to base and soil substrates
under highway pavements. where the barometric pump causes the inhalation
of humid air, which then condenses in those structures, causing an ever
increasing moisture content and sometimes instability.
Hydrologic
Cycle The
Hydrologic Cycle consists of the evaporation of water from oceans and
other bodies of open water; condensation to produce cloud formations;
precipitation of rain, snow, sleet or hail upon land surfaces; dissipation
of rain or melted solids by direct run-off into lakes and by seepage into
the soil. Thereby producing a continuing endless source of water in the
sub-grade.
Impermeable
The
ability of a material or product to reduce or eliminate gaseous
transmissions through it's mass; measured as the rate of Water Vapor
Transmission (WVT). Note: Not all materials that are waterproof are
vaporproof; all materials that are vaporproof are inherently waterproof.
Initial
Set
A degree of stiffening of the cement and water mixture. This is a degree
lees than final set and is generally stated as an empirical value,
indicating the time in hours and minutes required for a cement paste to
stiffen sufficiently to resist to an established degree the penetration of
a weighted test needle. (Refer to ASTM C191 or C286 for weight and
penetration data.)
Initial
stress
In prestressed concrete, the stresses occurring in the prestressed members
before any losses occur.
Jacking
Equipment
In prestress concrete, the device used to stress the tendons.
Jacking
Force
The temporary force exerted by the jacking device which introduces tension
into the tendons. Jacking
Stress In prestress concrete, the maximum stress occurring in a tendon
during stressing.
Keene's
Cement
A finely ground high density plaster composed of anhydrous, (calcined or
"dead burned") gypsum, the set of which is accelerated by the
addition of other materials.
Kelly
Ball
A device for determining the consistency of fresh concrete.
It is sometimes used as an alternative to the slump test.
Laitance
A residue of weak and non-durable material consisting of cement,
aggregate, fines, or impurities brought to the surface of overwet concrete
by the bleeding water
Lift
Layer of concrete.
Liquefaction
The change of state to a liquid. Term used instead of condensation in reference to substances,
which are usually gaseous.
Magnetite
An aggregate used in heavy weight concrete, consisting primarily of
ferrous metaferrite (Fe304). A black magnetic iron ore with a specific
gravity of approximately 5.2 and a Mohs hardness of about 6.
Marl
A calcareous clay, containing approximately 30 to 65 percent calcium
carbonate (05003), found normally in extinct fresh wafer basins, swamps,
or bottoms of shallow lakes.
Masonry
Cement
Hydraulic cement manufactured for use in mortars for masonry construction.
Normally a blend of two or more of the following materials: portland
cement, natural cement, portland-pozzolan cement, hydraulic lime, slag
cement, hydrated lime, pulverized limestone, talc, chalk,
pozzolan, clay or gypsum; also may include air en-training
additions.
Mass
Concrete
Any large volume of concrete cast in place intended to resist applied
loads by virtue of mass. Generally
a monolithic structure incorporating a low cement factor with a high
proportion of large coarse aggregate.
Mass
Curing
Adiabatic curing, using sealed containers.
Maximum
Size Aggregate
Aggregate whose largest particle size is present in sufficient quantity to
affect the physical properties of concrete; generally designated by the
sieve size on which the maximum amount permitted to be retained is 5 or 10
percent by weight.
Mixer
Equipment used for mixing or blending the materials used in the
manufacture of concrete, grout or mortar.
Mixing
Speed
Rate of mixer drum rotation or that of the paddles in a pan, open-top, or
trough type mixer, when mixing a batch; expressed in revolutions per
minute (rpm) or in peripheral] feet per minute of A point on the
circumference at maximum diameter.
Mixing
Time
For stationary mixers, mixing time is calculated in minutes from the
completion of charging the mixer until the beginning of discharge; for
truck mixer, time is calculated in total minutes at a specified mixing
speed. the period during which materials used in a batch of concrete are
combined by the mixer
Modulus
of Elasticity
A measure of the resistance of material to deformation. the ratio of
normal stress corresponding strain for tensile or compressive stresses
below the proportional limit of the material; elastic modulus is denoted
by the symbol "2".
Moist
Room
A room used for storing and curing cementitious test specimens. The
atmosphere of this room is maintained at a temperature of 73.4 3.0'F or
23.0*1.7'0 and relative humidity of at least 98 percent.
These facilities must be adequate to continually maintain
free moisture on the exteriors of test specimens.
Monolithic
A plain or reinforced mass of concrete cast as a single, one piece,
integral structure.
Mortar
A mixture of cement, sand and water. When used in masonry construction,
the mixture may contain masonry cement, or standard portland cement with
lime or other ad-mixtures which may produce greater degrees of plasticity
and/or durability.
Neat
Cement
Unhydrated hydraulic cement.
Neat
Cement-Paste
A mixture of water and hydraulic cement, both before and after setting and
hardening.
No-Fines
Concrete
A concrete mixture in which only the coarse gradation (3/8' to 3/4'
normally) of aggregate issued.
Non-agitating
Unit
A truck-mounted unit for transporting ready-mixed concrete short
distances, not equipped to provide agitation (slow mixing) during
delivery.
Non-evaporable
Water
The water in concrete which is irremovable by oven drying; chemically
combined during cement hydration.
Ottawa
Sand
A sand used as a standard in testing hydraulic cements by means of mortar
test specimens. Sand is
produced by processing silica rock particles obtained by hydraulic mining
of the orthoquartzite situated in open-pit deposits near Ottawa, Illinois;
naturally rounded grains of nearly pure quartz.
Overvibration
Excessive vibration of freshly mixed concrete during placement-causing
segregation.
Particle-Size
Distribution
Particle distribution of granular materials among various sizes; for
concrete material normally designated as gradation.
Usually expressed in terms of cumulative percentages smaller or
larger than each of a series of sieve openings or percentages between
certain ranges of sieve openings.
Pea
Gravel
Portion of concrete aggregate passing the 3/8' sieve and retained on a
No.4 sieve.
Peeling
A process in which thin flakes of matrix or mortar are broken away from
concrete surface; caused by adherence of surface mortar-to forms as forms
are removed, or to trowel or float in portland cement plaster.
Pining
Development of relatively small cavities in a concrete surface, due to
phenomena such as cavitation or corrosion.
Plane
of Weakness
The plane along which a structure under stress will tend to fracture; may
exist because of the nature of the structure and its loading, by accident,
or by design.
Plastic
A condition of freshly mixed concrete. mortar or cement -paste indicating
that it is workable and readily re-moldable, is cohesive, and has an ample
content of fines and cement but is not over wet.
Plastic
Consistency
Condition in which concrete, mortar, or cement paste will sustain
deformation continuously in any direction without rupture.
Plasticity
Property of freshly mixed concrete, cement paste or mortar which
determines its ease of molding or resistance to deformation.
Plasticizer
A material that increases the workability or consistency of a concrete
mixture, mortar or cement paste.
Porosity
The ratio of the volume of voids in the material to the total volume of
the material, including the voids, usually expressed as a percentage.
Portland
Blast- slag Cement Furnace
(ASTM C 595)The product obtained by intimately intergrinding or an
intimate and uniform blending a mixture of granulated
blast furnace slag and portland-cement clinker
Portland
Cement
(ASTM C 150) the product obtained by pulverizing clinker consisting
essentially of hydraulic calcium silicates.
Portland-Pozzolan
Cement
(ASTM C 595) The product obtained by intimately intergrinding a mixture of
portland-cement clinker and pozzolan, or an intimate and uniform blend of
portland cement and fine pozzolan.
Post-tensioning
A method of prestressing concrete in which the tendons are tensioned after
the concrete has hardened.
Pozzolan
(ASTM C 618) A siliceous, or siliceous and aluminous material, which in
itself possesses little or no cementitious value but will, in a finely
divided form, such as a powder or liquid and in the presence of moisture,
chemically react with calcium hydroxide at ordinary temperatures to form
permanent, insoluble compounds possessing cementitious properties.
Precast
A concrete unit, structure or member that is cast and cured in an area
other than its final position or place.
Preplaced
Concrete
Concrete manufactured by placing clean, graded coarse aggregate in
a form and later injecting a portland cement-sand grout under pressure, to
fill the voids.
Proportioning
Selection of proportions of material for concrete to make the most
economical use of available materials to manufacture concrete of the
required strength, placeability, and durability,
Prestressed
Concrete
Concrete in which stresses have been introduced which are opposite
in sense to those that the structural member will be expected to carry
during its use.
Pretensioning
A method of prestressing reinforced concrete in which the steel is
stressed before the concrete has hardened and restrained from gaining its
unstressed position by bond to the concrete.
Pumping
(of Pavements) The ejection of a mixture of water and solid materials such
as clay or silt along cracks, transverse or longitudinal joints, and along
pavement edges caused by downward slab movement due to the passage of
heavy loads, machinery or equipment over the pavement after free water has
accumulated in or on the subbase, subgrade or basecourse.
Reactive
Aggregate
(See alkali-aggregate reaction)
Rebound
Wet shotcrete or sand and cement which bounces away from a surface again
at which pneumatically applied mortar is being projected.
Refractory
Concrete
Concrete having refractory properties, suitable for use at high
temperatures. Calcium-aluminate
cement and refractory aggregates are normally used for the manufacture of
this product.
Reinforced
Concrete
A.
Concrete in which reinforcement, other than that provided for
temperature changes for shrinkage, has been embedded in such a- manner
that the two materials act together in resisting forces.
B.
Concrete in which steel bars have been placed to sustain the
tensile stresses.
Retardation
Delaying
the hardening or strength gain of fresh concrete, mortar or grout.
Retarder
An admixture which extends the setting time of cement paste, an
We manufacture concrete admixtures,
penetrating concrete sealers, penetrating concrete floor sealers, flooring sealers, concrete
waterproofers, brick
sealers, block sealers, stucco sealers, plaster waterproofers, shotcrete
waterproofers,
gunite waterproofers, mortar sealers, concrete cleaners, and concrete repair products.