Glossary
of Concrete Construction Terms |
| |
| Term |
Definition |
| |
AAC
(Autoclaved Aerated Concrete) |
Lightweight
precast concrete with high thermal qualities and fire resistence. Mix
design is composed of portland cement, sand or siliceous material, lime,
gypsum, finely powdered aluminum, and water. |
Abacus |
Flat
slab atop a column capital which supports the architrave. |
Abrams
Law |
Rule
stating: given concrete materials and condition of test, the ratio of
the amount of water to the amount of cement in the mixture determines
the strength of the concrete, provided the mixture is of workable consistency. |
Abrasion
resistance |
Ability
of a concrete surface or coating to resist being worn away by rubbing
or friction. |
Abrasive
blasting |
Push
an abrasive medium at high velocity against concrete to clean or profile
the surface in preparation for coating. |
ABS
pipe
(Acrylonitrile Butadiene Styrene) |
A
plastic pipe sold in 10 and 20 foot lengths in various diameters for
plumbing stacks and drains. |
| 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. |
| 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 |
Process
by which a liquid is drawn into a porous soild material. |
abutment |
Support
at either end of an arch, beam, or bridge; a foundation that carries
gravity and also trust loads. |
Accelerator |
Admixture
that will shorten the set time of concrete or speed strength development. |
Acetone |
Solvent
commonly used as a carrier for solvent based sealers. |
Acid
stain |
A
stain containing inorganic salts dissolved in an acidic, water-based
solution that reacts chemically with the minerals in hardened concrete
to produce permanent, transparent color. Colors are often earth tones. |
| Adhesion |
Sticking
together of substances or surfaces that are in contact with one another. |
| 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 |
All
materials, other than portland cement, water, and aggregates, that are
added to concrete, mortar, or grout immediately before or during mixing
that is used to modify concrete's mixed, setting, or hardened properties. |
| Adsorption
Water |
Water
held on surfaces in a material by either physical and/or chemical forces.
|
Aggolomeration |
Formation
of masses or aggregates of pigments; not dispersed. |
| Aggregate |
Granular
material, such as sand, gravel, crushed stone, and rock, added to a
cementing medium to improve its structural performance. |
Agitator |
Device
used to cause motion in confined fluids |
| 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 admixture |
Admixture
that through agitation during production of concrete causes the development
of a system of microscopic air bubbles that increase its workability
and aid in freeze/thaw resistance. |
| Alkali-Aggregate
Reaction |
Older
terminology for Alkali-Silica Reactivity (ASR) |
| Alkali-Silica
Reactivity (ASR) |
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. |
Alligatoring |
Wrinkled
appearance in coatings caused by surface imperfections. Often caused
by incompatibility of a newly applied coating with an existing surface
coating or sealer. (AKA, orange peeling or fish eyeing) |
Aluminous
cement |
Hydraulic
cement in which the principal constituents are calcium aluminates, instead
of calcium silicates which comprise the major ingredients of portland
cement. |
Anchor
bolt |
Large
J- or L-shaped bolts embedded in concrete or mortar for the purpose
of fastening a building frame to a concrete or masonry foundation. |
Anhydrous |
Free
from moisture or water in any form. |
Antiquing |
Decorative
concrete technique that gives a surface an aged or mottled appearance. |
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 causing expansion, cracking or popouts in concrete. |
Auger |
Machine
used for boring or drilling deep straight holes. |
| Autoclave |
Used in curing of concrete products and in the testing of hydraulic
cement. Chamber in which an environment of steam and high pressure is
produced. |
| |
Back
blocking |
A
short piece of gypsum wallboard adhesively laminated behind the joints
between each framing member to reinforce the joint. |
Back
clip |
Clips
attached to the back of gypsum board that fit into slots or other formations
in the framing to hold the gypsum board in place. |
Backfill |
Material
used to refill an area that has been excavated. |
Back
saw |
Small
toothed, joint-cutting saw with a metal back strip to keep the saw rigidly
in line. |
Backhoe |
Excavating
machine with a bucket attached to a hinged boom that is drawn toward
the machine. |
Ballast |
Heavy
material, such as water, sand, or metal used to soley increase a machine's
weight. |
Band
saw |
Machine
saw with a narrow endless blade that runs over pulleys. |
Barrel
of cement |
A
unit of weight for cement which is 376 lbs net, equivalent to 4 US bags
(sacks) of portland cement. |
Baseplate |
Steel
plate inserted between a column and the foundation, used to spread the
load of the column to a larger area of the foundation. |
Batch |
Production
of a quantity of concrete based on volume. |
Batch
plant |
Operating
equipment facility for mixing concrete materials (AKA, mixing plant) |
Batch
weights |
Measured
amount of sand, stone, cement, and water that make up batch concrete. |
Batt
insulation |
Sheets
of fiber or wool insulation with a paper backing. Usually sized to fit
snugly in framed cavity. |
Batter
boards |
Board
frame supported by stakes set back from the corners of a structure that
allows for relocating certain points after excavation. Saw kerfs in
the boards indicate the location of the edges of the footings and the
structure being built. |
Bearing
capacity |
Maximum
allowable load placed on a structure. |
Bed
joint |
Horizontal
layer of mortar on which a masonry unit is laid. |
Bedrock |
Solid
layer of rock beneath ground level. |
| 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-furance
slag |
Nonmetallic
product, consisting of silicates and aluminosilicates of cacium and
other bases, that is developed in a molten condition simultaneously
with iron in a blast furnace. |
Bleed
through |
Color
change caused by the diffusion of color from an underlying surface. |
| Bleed
water (bleeding) |
Water
that rises to the surface of freshly placed concrete due to segregation.
This may interfere with finishing operations. |
Blistering |
Blisters
or bubbles that form on coatings as a result of loss of adhesion with
the underlying substrate. |
Block |
Concrete
made with fine aggregate and cement that is shaped in a mold. |
Bonding
agent |
Agent
used to increase the adhesiveness of a coating or topping to the existing
surface. Also used to bond new concrete to old. (AKA, primer) |
Bond
breaker |
Agent
that prevents adhesion of materials to concrete. |
Brick
set |
Wide-blade
chisel used for cutting bricks and concrete blocks. |
Broadcast |
Hand
tossing a dry-shake color hardener, decorative aggregate, or other dry
material in a uniform layer over fresh concrete, overlays, or coatings
in order to add color or texture. |
Broom
finish |
Pushing
a broom across freshly placed concrete in order to obtain surface texture. |
Brown
coat |
Second
coat of plaster or stucco in three-coat process. |
Bull
float |
Tool
with a 3- to 4-foot rectangular blade made of wood, resin, aluminum,
or magnesium used to eliminate high and low spots in freshly placed
concrete. |
Bush
hammer |
Hammer
with rows of pyramid-shaped points used to roughen or profile concrete
surfaces. |
| |
| Caisson
pile |
A cast-in
place pile made by driving a tube, excavating it, and filling the cavity
with concrete. |
| 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. |
calcium
chloride vapor-emission test |
ASTM
test used to measure the volume of moisture vapor released from a concrete
substrate over time (typically 24 hours). Excessive moisture released
from a slab can affect the performance and bonding of overlays, coatings,
and sealers. |
| Calcium-silicate
hydrate |
Any
of the various reaction products of calcium silicate and water, produced
in the hydration of cement. |
| 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%. |
| Cast-in-place |
Mortar
or concrete which is deposited in the place where it is required to
harden as part of the structure, as opposed to precast concrete |
| Cavity
wall |
A
wall built of two or more wythes of masonry units separated by a continuous
air space (with or without insulating materials) and in which the wythes
are securely tied together with rigid corrosion resistant metal ties. |
| 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, high early strength |
Cement
characterized by attaining a given level of strength in mortar or concrete
earlier than normal cement; referred to as Type 30. |
| Cement,
hydraulic |
Cement
that sets and hardens by chemical interaction with water and is capable
of doing so under water. |
| Cement,
Portland |
A hydraulic
cement produced by pulverizing portland cement clinker and usually containing
calcium sulfate. |
| Cleanout |
An
opening in the first course of masonry for cleaning mortar droppings
prior to grout placement in grouted masonry. Required in high lift grouting. |
| Collar
joint |
The
vertical longitudinal joint between wythes of masonry. |
| Compressive
strength |
The
measured maximum resistance of a concrete or mortar specimen to axial
compressive loading; expressed as force per unit cross-sectional area;
or the specified resistance used in design calculations. |
| Composite
wall |
A
multiple wythe wall in which at least one of the wythes is dissimilar
to the other wythe with respect to type or grade of units or mortar. |
| Concrete |
A composite material that consists essentially of a binding medium within
which are embedded particles or fragments of aggregate, usually a combination
of fine aggregate and coarse aggregate; in portland-cement concrete,
the binder is a mixture of portland cement and water.
|
| Concrete,
architectural |
Concrete
which will be permanently exposed to view and which therefore requires
special care in selection of the concrete materials, forming, placing,
and finishing to obtain the desired architectural appearance. |
| Concrete Flying Form System |
method of creating concrete slabs for high-rise buildings. Concrete is poured over a series of trusses. When the concrete is cured, the forms can be moved and placed for flooring of multi-story buildings. |
| Concrete
masonry unit, hollow |
A
unit whose net cross-sectional area in any plane parallel to the bearing
surface is less than 75 percent of its gross cross-sectional area measured
in the same plane. |
| Concrete
masonry unit, solid |
A
unit whose net cross-sectional area in every plane parallel to the bearing
surface is 75 percent or more of its gross cross-sectional area measured
in the same plane. |
| Concrete,
normal weight refractory |
Refractory
concrete having a unit weight (bulk density) greater than 1600 kilograms
per cu.m. |
| Concrete,
roller-compacted |
Concrete
compacted by roller compaction; concrete that, in its unhardened state,
will support a roller while being compacted. |
| Concrete,
structural |
Concrete
used to carry structural load or to form an integral part of a structure;
concrete of a quality specified for structural use. |
| Control
joint |
A
continuous unbonded masonry joint to regulate the location and amount
of separation resulting from the dimensional change of different parts
of a structure so as to avoid the development of excessively high stresses. |
| Curing |
The
maintenance of a satisfactory moisture content and temperature in concrete
during its early stages so that desired properties may develop. |
| |
| Dampproofing |
Prevention
of moisture penetration due to capillary action by the addition of one
or more coatings of a compound that is impervious to water. |
Darby
(derby, derby float, derby slicker) |
A
stiff straightedge of wood or metal used to level the surface of wet
concrete. A portable machine with large paddles like fan blades used
to float and finish concrete floors and slabs. A large power-driven
machine mounted on wheels that ride on steel pavement forms and is used
to finish concrete pavements. |
| Deformation |
The
process of changing the dimensions of a structure by applying a force. |
Derated
concrete |
Concrete
that has had a gas-forming chemical added to it so that when it sets
it contains many air holes and is lightweight. |
Dispersants |
A
material capable of holding finely ground particles in suspension. Used
as a slurry thinner or grinding compound. |
Division
plate |
A
concrete forming accessory used to create a break in a concrete sidewalk
or curb and gutter. This engineered break minimizes the chances of the
poured concrete cracking due to the surrounding ground shifting as a
result of variety of factors including freezing, thawing, or heat expansion. |
Division
plate (full) |
Full
plates are used as bulkheads in the curb and gutter system and also
are used to hold expansion material during concrete placement. |
Division
plate (punched for dowel) |
Division
plates punched for dowel are full division plates with slots punched
on the bottom to accommodate the use of dowels or rebar. The punched
slots hold the dowels or rebar in place during placement and prevents
the material from floating in the placement. |
Division
plate (skeleton) |
Skeleton
division plates are used to support the curbface form and add support
for the curb and gutter system. |
Division
plate (slotted for rebar) |
Also
known as an S/B division plate. Division plates with slots for rebar
provide the contractor with the ability to ensure the rebar will stay
exactly where it is positioned into a curb and gutter placement, eliminating
problems with the final rebar positioning. |
| Dormancy
period |
Time
period that concrete retains it workability. |
DOT |
The
acronym for the Department of Transportation. |
Dowel |
A
cylindrical piece of stock inserted into holes in adjacent pieces of
material to align and/or attach the two pieces. |
Dowel-bar
reinforcement |
Short
sections of reinforcing steel that extend from one concrete placement
into the next. They are used to increase strength in the joint. |
Dowel
lubricant |
A
lubricant applied to dowels placed in adjoining concrete slabs to allow
longitudinal movement in expansion joints. |
Dowel
screw |
A
threaded dowel. |
Dry
concrete |
Concrete
that has a low water content, making it relatively stiff. The effects
are a lower water-cement ratio, less pressure on forms, lower heat of
hydration, and a consistency that allows for placement on a sloping
surface. |
Dry
pack |
A
low-slump grout tamped into the space in a connection between pre-cast
concrete members. |
Dry
shake (dry topping) |
A
concrete surface treatment, such as color, hardening, or antiskid, which
is applied to a concrete slab by shaking on a dry, granular material
before the concrete has set and then troweling it in. |
Drying
shrinkage |
Contraction
caused by the loss of moisture, particularly in concrete, mortar, and
plaster. |
| Durability |
The
ability of concrete to resist weathering action, chemical attack, abrasion,
and other conditions of service. |
| |
| Early
strength |
Strength
of concrete or mortar usually as developed at various times during the
first 72 hr after placement. |
Edger
(edging trowel) |
A
tool used to fashion finishing edges or round corners on fresh concrete
or plaster. |
Efflorescence |
The
process by which water leeches soluble salts out of concrete or mortar
and deposits them on the surface. Also used as the name for these deposits. |
Elastic |
Able
to return to its original form after the removal of stress. |
Elastic
shortening |
The
shortening of a member in pre-stressed concrete that occurs on the application
of forces induced by pre-stressing. |
| Elasticity |
The
ability of a material to return to its original shape after being stretched. |
| Embankment |
A
fill with a top higher than the adjoining natural surface. |
End
plugs |
Heavy-gauge
metal cap ends for the straight steel forms. |
| Entrained
Air |
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. |
Expansion
joint |
A
surface divider joint that provides space for the surface to expand.
It is usually composed of a fibrous material (~1/2" thick) and often
installed in and around a concrete slab to permit it to move up and
down (seasonally) along the non-moving foundation wall. |
Expansive-cement
concrete |
A
concrete made from expansive cement for the purpose of reducing or controlling
volume changes that occur during curing. |
Exposed
aggregate finish |
A
method of finishing concrete which washes the cement/sand mixture off
the top layer of the aggregate - usually gravel. It is often used in
driveways, patios and other exterior surfaces. |
Extension
chute |
An
additional chute used by a concrete contractor to extend the length
of the existing chutes from a ready-mix concrete truck. They are frequently
used to pour floors. |
Extension
pocket |
Concrete
forming accessories used to hold a form over a trench without adding
additional supports underneath. This device consists of a stake pocket
that is attached to an adjustable horizontal brace and then attaches
to the stake pocket of the form. This device allows the forms to be
set in areas that have been trenched by allowing the form bracing to
"float" above and over the trench. |
| |
F
numbers |
The
specification of the degree of flatness that a slab or floor must have.
The degree of flatness of a concrete floor is extremely critical for
warehouse or manufacturing plant floors where specialized materials
handling equipment may be guided by wires under the concrete floor. |
Face
forms |
Concrete
forms that are used to create a desired curb profile. They attach to
the curb and gutter form set up by hooking to the clips of the division
plate. Face forms are designed based on the amount of batter specified. |
Faced
concrete |
To
finish the front and all vertical sides of a concrete porch, step(s),
or patio. Normally the "face" is broom finished. |
Fair
face concrete |
A
concrete surface that, on completion of the forming process, requires
no additional (concrete) treatment other than curing. |
| 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. |
Fat |
Material
accumulating on a trowel during smoothing. Fat is used to fill in small
imperfections. |
| Fiber
Reinforcing |
Randomly-oriented
fibers distributed through concrete to improve certain properties such
as tensile strength or crack resistance. |
| 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. |
| Fines |
Clay
or silt particles in soil. |
| Finish
Grade |
The
final grade required by specifications. |
| Finishing |
Leveling,
smoothing, consolidating, and otherwise treating surfaces of fresh or
recently-placed concrete to produce a desired appearance and service. |
| 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. |
| Floating |
Floating
removes humps (high spots) and fills in valleys (low spots). It
also compacts the concrete by embedding large aggregate just beneath
the surface and consolidating mortar at the surface in preparation for
other finishing operations. |
| 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. |
| Foot |
In
tamping rollers, one of a number of projections from a cylindrical drum. |
| Frequency
|
Referring
to rotational speed of the eccentric shaft - usually rated in "Vibrations
Per Minute" - which is equal to the RPM of the shaft. |
| Freeze-thaw |
Damage
caused by water that has penetrated into concrete and is exposed to
repeated cycles of freezing and thawing. MetaMax® reduces the potential
for freeze-thaw by reducing the porosity of 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. |
| Gauge
Rake |
A tool with an adjustable
depth gauge designed for application of high-build coatings or cementitious
toppings at a preset, uniform thickness. |
| 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. |
| Grade |
Usually the surface elevation
of the ground at points where it meets a structure. Also, surface slope. |
| Grain
Size Curve |
A
soil graph analysis showing the percentage size variations by weight. |
| Granular
Material |
A sandy type of soil
with particles that are coarser than cohesive material and do not stick
to each other. |
| Granulated
Blast Furnace Slag |
A glassy, granular material
formed when molten blast furnace slag is rapidly chilled. Ground granulated
slags are sometimes used in concrete mixtures as a cement replacement
to help reduce permeability and improve durability. May also slow setting
and extend the working time of the concrete. |
| Gravel
|
A cohesion less aggregate
of rock fragments with varying dimensions of 3.0 to .08 inches. |
| Grinding |
A mechanical surface
preparation method using rotating abrasive stones or discs to remove
thin coatings and mastics or slight flaws and protrusions. |
| Groover |
A tool with a V-shaped
bit used to create control joints in plastic concrete. |
| Grout |
A mixture of cementitious
materials and water, with or without aggregate, proportioned to produce
a creamy consistency. Can be purchased preblended in a multitude of
colors to define joints and sawcuts in decorative concrete slabs or
walls, especially those with stone, brick, or tile patterns. |
| Gumbo |
Material in the plastic
state identified by a soapy or waxy appearance. |
| Gunite
|
A term sometimes used
to designate dry-mix shotcrete. |
| |
