Glossary of Concrete and Paving

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Nov 29, 2013 (3 years and 9 months ago)

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Glossary of Concrete and Paving




Abrams' law

The rule stating that with given materials, curing, and testing conditions,
concrete strength is inversely related to the ratio of water to cement. Low
water
-
to
-
cement ratios produce higher strengths.

Abrasiv
e aggregate

The aggregate used to increase the abrasiveness of the surface of a concrete
slab.

Absolute volume

In concrete, the actual volume occupied by the different ingredients determined
by dividing the weight of each ingredient pounds, by its specific

gravity, times
the weight of one cubic foot of water in pounds.


Example: Absolute Volume of one sack of cement equals: 94 ÷ (3.15 x 62.4) =
0.478 cubic feet.

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.

Absorption loss

Water losses that occur until the aggregate in a concrete mix is saturated. See
aggregate
.

Acceleratio
n

The speeding up of the setting or hardening process of concrete by using an
additive in the mix. The process of acceleration allows forms to be stripped
sooner or floors finished earlier. See
a
ccelerators
.

Accelerators

Material additives used to accelerate, or reduce, the setting time of concrete
causing it to harden faster. Accelerators often include calcium chloride, or
aluminum sulfate or other acidic materials. See
set retarders
.

Accessories

The items used to assemble scaffolding, shoring, and forms, other than the
walers, frames, and the forms themselves in the placing of concrete. See
curb
and gutter forms
,
flatwork forms
,
filler forms
,
flexible forms
,
straight forms
,
and
walers
.

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.


Adjustable Hanger

A forming accessory, a metal strip, used to suspend or support metal forms or
metal form attachments when
traditional methods of anchoring forms or form
attachments cannot be used due to trenching or prior concrete placement. See
hanger
.


Admixture

A material, other than aggregate, cement, or water, added in small quantities
to the mix in order to produce some desired modifications, either to the
physical or chemical properties of the mix

or of the hardened product. The
most common admixtures affect plasticity, air entrainment, and curing time.
These admixtures are often referred to as
plasticizers
, superpla
sticizers,
accelerators
, dispersants, and water
-
reducing agents.

Advanced Cement
-
Based Materials (ACBM)

A center at Northwestern University established by the National Science
Foundation to crea
te new cement

based materials with improved properties.

Aerated concrete

Concrete formed using gas
-
forming admixtures such as powdered zinc or
aluminum combined with calcium hydroxide or hydrogen peroxide that form
hydrogen or oxygen bubbles in the cement
mix.

Aggregate

A mixture of sand, rock, crushed stone, expanded materials, or particles that
typically compose 75% of concrete by volume improve the formation and flow
of cement paste and improve the concrete's structural performance. See
concrete
.

Aggregate, exposed or exposed aggregate

A concrete surface with the aggregate exposed, formed by applying a retarder
to the surface before the concrete has set, and subsequently remo
ving the
cement paste to the desired depth. See
aggregate
.

Aggregate testing

Any of a number of tests performed to determine the physical and chemical
characteristics of an aggregate. Common tests
are for abrasion, absorption,
specific gravity, and soundness. See
aggregate
.

Agitating speed

The rate at which a concrete or mortar mixer rotates the drum or blades in
order to agitate mixed mater
ials to prevent segregation or setting. See
concrete mixture
,
mixing speed
,
segregation
, and
set
.

Agitation

The rotation of, or moving of blades through, a drum containing concrete o
r
mortar to prevent segregation or setting of mixture. See
concrete

and
segregation
.

Agitator

A mechanical device used to maintain plasticity and to prevent segregation,
particularly in concrete and mortar. See
concrete

and
segregation
.

Agitator truck

Vehicle designed to take pre
-

or ready
-
mixed concrete and deliver it ready to
be used at a construction site. The truck bed contains a large barrel or drum
that is used to continuously roll
or agitate the concrete mixture keeping it from
solidifying before use. See
ready
-
mixed concrete
.

Air content

The amount of entrained or entrapped air in concrete or m
ortar, exclusive of
pore space in aggregate particles, usually expressed as a percentage of total
volume of concrete or mortar.

Air
-
entrained agent

An additive to hydraulic cement or an admixture for concrete or mortar that
causes air to be incorporated in

the form of minute bubbles on the concrete or
mortar during mixing, usually to increase its workability and frost resistance.
See
hydraulic cement
.

Air
-
entrained concr
ete

A Portland cement with an admixture that causes a controlled quantity of
stable, very small air bubbles to form in the concrete during mixing. See
non
-
air
-
en
trained concrete
.


Air
-
permeability test

A procedure for determining the fineness of powdered material such as cement.

Air content

The volume of air present in a concrete or mortar mix, expressed as a
percentage of the total volume. A controlled air content prevents concrete from
cracking during the freeze/thaw cycle.

Air meter

A device for measuring the air content of a c
oncrete or mortar mix. See
air
content

and
mix
.

Air slacking

The absorption of moisture and carbon dioxide from the air b
y lime or cement.

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.

American Association of State Highway and Transportation Officials (AASHTO)

An organization that represents highway and transportation departments in
the
50 states, the District of Columbia and Puerto Rico.

American Concrete Institute (ACI)

An international organization dedicated to providing knowledge and information
for the best uses of concrete
.

American National Standards Institute (ANSI)

An organiz
ation that represents the United States in the International
Organization for Standardization (ISO).

American Standard of Testing Materials (ASTM)

An organization that has developed a variety of methods for testing the
strength of cement and other building

materials to ensure it complies with
needed strength requirements.

Anchor bolts

Bolts to secure a wooden sill plate to concrete, masonry floor, or wall.

Angle float (angle trowel)

A trowel with two surfaces meeting at right angles. An angle float is used
for
finishing plaster or concrete in an inside corner. See
float

and
trowel
.

Apron

A slab of concrete

extending beyond the entrance to a building, particularly at
an entrance for vehicular traffic. At an airport, the pavement adjacent to
hangars and appurtenant buildings. See
paving forms
.


Architectural concrete

Structural or nonstructural concrete that will be permanently exposed to view
and therefore requires special attention to uniformity of materials, forming,
placing, and finishing. This type of concrete is frequently cast in a mold and has
a pattern on the surface. See
fair face concrete
.

Arrissing tool

A special float used to round the edges of freshly placed concrete. See
concrete

and
float
.

Asphalt

A black petroleum residue, which can be anywhere from solid to semisolid at
room temperature. When heated to the temperature of boiling water, it
becomes able to be poured. It is used in roofing
materials, surfacing roads, in
lining the walls of water
-
retaining structures such as reservoirs and swimming
pools, and in the manufacture of floor tiles. Asphalt should not be confused
with tar, a similar looking substance made from coal or wood and inco
mpatible
with petroleum derivates.

Asphalt cement

Asphalt that has been refined to meet the specifications for use in paving and
other special uses. It is classified by penetration.

Asphalt expansion joint

Premolded felt or fiberboard impregnated with asph
alt and used extensively as
an expansion joint for cast
-
in
-
place concrete.

Asphalt leveling course

A course of asphaltic concrete pavement of varying thickness spread on an
existing pavement to compensate for irregularities prior to placing the next
course
.

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.

Autoclaved Aerated Concrete (AAC)

Autoclaved Aerated Concrete (AAC) is a mixture

of portland cement, quicklime,
sand, water and aluminum powder. The chemical interaction of these “aerated"
natural materials creates a porous, closed cell masonry material with a density
of approximately forty
-
five (45) pounds per cubic foot, roughly one
-
third the
weight of stone concrete. A high temperature, high
-
pressure steam cure in an
autoclave speeds additional chemical reactions, which allow the AAC to reach
full strength in less than twenty
-
four (24) hours. AAC is easy to use on a job
site and pro
vides excellent sound proofing and fire protection.

Auxiliary reinforcement

In a pre
-
stressed concrete member, refers to all reinforcing steel other than the
pre
-
stressing steel. See
pre
-
stressed concrete
.



Backfill

The replacement of excavated earth into a trench around or against a
basement crawl space foundation wall.

Bag

A quantity of Portland cement; 94 pounds in the United States, 87.5 pounds in
Canada, 112 po
unds in the United Kingdom, and 50 kilograms in most other
countries. Different weights per bag are commonly used for other types of
cement. Same as sack.

Ball test

A test to determine the consistency of freshly mixed concrete by measuring the
depth of pen
etration of a cylindrical metal weight or plunger that has been
dropped into it. See
slump test
.

Ballast

A layer of coarse stone, gravel, slag, etc., over which concrete is p
laced.

Band

A group of small bars or the wire encircling the main reinforcement in a
concrete structural member to form a peripheral tie. A band is also a group of
bars distributed in a slab, wall, or footing.

Bar

A deformed steel member used to reinforce
concrete. See
rebar

and
reinforced
concrete
.

Bar support (bar chair)

A rigid device of f
ormed wire, plastic, or concrete, used to support or hold
reinforcing bars in proper position during concrete operations. See
chair

and
high chair
.

Barrel

A unit of weight measure for Portland cement, equivalent to four bags or 376
pounds. See
bag
.

Base course / base

A layer of material of specified
thickness constructed on the subgrade or sub
-
base of a pavement to serve one or more functions, such as distributing loads,
providing drainage, or minimizing frost action. See
su
b
-
base
.


Batch

The quantity produced as the result of one mixing operation, as in a batch of
concrete.

Batch box

A cont
ainer of known volume used to measure the constituents of concrete or
mortar in proper proportions.

Batch mixer

A machine that mixes concrete, grout, or mortar in batches in accordance to a
design mix. Each batch is used completely before a second batch i
s started.

Batch plant

A temporary concrete mixing plant usually erected at a jobsite to fulfill the
specific needs of that job. They are typically erected when a large volume of
concrete will be required at a specific job. Batch plant utilization reduces

transportation costs, increases control of the mixture, and speeds up job
completion.

Batter

A slope, such as that of the outer side of a wall, that is wider at the bottom
than at the top. The measurement of batter is the horizontal distance between
the
top and bottom of a slope. See
curb face batter
.

Batter level

An instrument used to measure the inclination of a slope. See
batter
.

Battered wall

A wall that slopes backward, as by recessing or sloping masonry in successive
courses.

Bedding

A prepared base for masonry or concrete.

Beetle

See
m
aul
.

Bending schedule

A list of reinforcement prepared by the designer or detailer of a reinforced
concrete structure which shows the shapes, dimensions, and location of every
bar, and the number of bars required. See
reinforced concrete

and
rebar
.

Bg cement

A bag of cement.

Binder

Almost any cementing material, either hydrated cement or a p
roduct of cement
or lime and reactive siliceous materials. The kinds of cement and the curing
conditions determine the general type of binder formed. Any material, such as
asphalt or resin, that forms the matrix of concretes, mortars, and sanded
grouts.


Bituminous cement

A class of dark substances composed of intermediate hydrocarbons. Bituminous
cement is available in sol
id, semisolid, or liquid states at normal temperatures.

Blaine apparatus

Air
-
permeability apparatus for measuring the surface area of a finely ground
cement. See
Blaine fineness

and
Blaine test
.

Blaine fineness

The fineness of granular materials such as cement and pozzolano, expressed as
total surface area in square centimeters per gram, determined by the Blaine
air
-
permeability appa
ratus and procedure. See
Blaine apparatus
,
Blaine test
,
and
pozzolano
.

Blaine test

A method for determining the fineness of cement or other material based on
the permeability to air of a sample prepared under specified conditions. See
Blai
ne apparatus

and
Blaine fineness
.

Blanket

Insulation sandwiched between sheets of fabric, plaster, or paper facing, used
for protecting fresh concrete during curing. See
curing
.

Bleeding

The autogenous flow of mixing water within, or its emergence from, freshly
placed concrete or mortar. Bleeding is caused by the settlement of the solid
materials within the mass. B
leeding is also called water gain.

Blended cement

A hydraulic cement consisting of an intimate and uniform blend of granulated
blast
-
furnace slag and hydrated lime, Portland cement and granulated blast
-
furnace slag, Portland cement and pozzolano, or Portla
nd
-
blast
-
furnace slag,
cement, and pozzolano. Blended cement is produced by intergrinding Portland
cement clinker with the other materials or by a combination of intergrinding
and blending. See
hydraulic cement
,
Portland cement
, and
pozzolano
.

Block out

Th
e installing of a box or barrier within a foundation wall to prevent the
concrete from entering an area. For example, foundation walls are sometimes
"blocked" in order for mechanical pipes to pass through the wall, to install a
crawl space door, and to dep
ress the concrete at a garage door location.

Blowhole

In concrete, a bug hole or small regular or irregular cavity, not exceeding 15
mm in diameter, resulting from entrapment of air bubbles in the surface of
formed concrete during placement and compaction.

See
placing
,
placement

and
compaction
.

Blowout

Term used when the ready
-
mixed concrete breaks through the forming boards
due to insufficient bracing. Also, the localized buckling or breaking up of rigid
pavement as a result of excessive longitudinal pressure. See
ready
-
mixed
concrete
.

Blowup

Slang term used to describe the unexpected fast setting of concrete that does
not allow proper finishing. See
set
.

Board foot

The basic unit of measurement for lumber. One board foot is equal to a 1" thick
board, 12" in width and 1' in length. Therefore, a 10' long, 12" wide, and 1"
thick piece contains 10 board feet. Nomi
nal sizes are assumed when calculating
board feet.


Bond

The adhesion of cement paste to aggregate and or the rebar. See

aggregate

and
rebar
.

Bond breaker

A strip of material to which the cement does not adhere. See
bond

and
form
release agent
.

Bonded posttensioning

A process in posttensioned construction whereby the annular space
s around the
tendons

are grouted after stressing in a manner that the tendons become
bonded to the concrete section.

Brace/bracing

A concrete forming accessory that acts as a te
mporary support for aligning
vertical concrete formwork. One end of the brace attaches to the form and the
other anchors to the ground.


British thermal unit (BTU)

A sta
ndard measurement of the heat energy required to raise the temperature
of one pound of water one degree Fahrenheit.

Brittle

A material that fractures easily such as cement.

Broom finish

Concrete that has been brushed with a broom when fresh in order to imp
rove
its traction or to create a distinctive fine
-
lined texture.

Brown millerite

An oxide of calcium, aluminum, and iron commonly formed in
Portland cement

and high alum
ina cement mixtures.

Bull float

A board of wood, aluminum, or magnesium mounted on a pole and used to
spread and smooth freshly placed, horizontal concrete surfaces. After
screeding, the first stage in the final finish of concrete, smoothes and levels
hil
ls and voids left after screeding. Sometimes substituted for darbying. See
darby
,
float
, and
screeding
.

Burlap

Material often used to protect newly finished concrete from rain as well as
maintaining moisture in a slab. See
Visqueen

and
curing blanket
.

Burn

A construction slang term used to describe the darkish concrete color that
occurs as a result of over trowelin
g. See
trowel
,
troweling
, and
trowel finish
.

Bush
-
hammer

A tool having a serrated face, as rows of pyramidal points, used to develop an
architectural finish for concrete surfaces.

Bush
-
hammered concrete

Concrete with an exposed aggregate finish that has been obtained
by removing
the surface cement using a percussive hammer with a serrated face. See
aggregate, exposed
.

Butterfly

A hand tool used to trowel finish concrete curb and gut
ter work. See
trowel
,
troweling
,
trowel finish
, and
curb and gutter
.





Caisson

A 10" or 12" diameter hole drilled into the earth and embedded into bedrock 3
to 4 feet. The structural
support for a type of foundation wall, porch, patio,
monopost, or other structure. Two or more "sticks" of reinforcing bars (rebar)
are inserted into and run the full length of the hole and then concrete is poured
into the caisson hole. A caisson is design
ed to rest on an underlying stratum of
rock or satisfactory soil and is used when unsatisfactory soil exists. See
rebar

and
pouring
.

Calcite

The main raw material used in the manufacture of Portland cement. Calcite is a
crystallized form of calcium carbonate and is the principal component in
limestone, chalk, and marble.

Calcium aluminate cement

A combin
ation of calcium carbonate and aluminates that have been thermally
fused or sintered and ground to make cement.

Calcium chloride

An additive used in ready
-
mix to accelerate the curing, usually used during
damp conditions. See
ready
-
mixed concrete
.

Capillary space

A term used to describe air bubbles that have become embedded in cement
paste.

Cast
-
in
-
place concrete

Concrete that is poured into forms that are erected at th
e job site. It is the
same as the term sitecasting. See
pre
-
cast concrete
.

Casting

Pouring a liquid material, or slurry, like concrete, into a mold or form whose
physic
al form it will take on as it solidifies. See
pouring
.

Casting bed

A permanent, fixed form, in which permanent pre
-
cast concrete forms are
produced. See
pre
-
cast concrete
,
cast
-
in
-
place concrete
.

Cefi

A contraction meaning a cement finisher.

Cem. Fin.

The construction abbrev
iation for a cement finish.


Cement

A material composed of fine ground powders that hardens when mixed with
water. Cemen
t is only one component of concrete. The gray powder that is the
"glue" in concrete.

Cement
-
aggregate ratio

The ratio of cement to aggregate in a mixture, as determined by weight or
volume.

Cement content / cement factor

A quantity of cement contained in a

unit volume of concrete or mortar,
ordinarily expressed as pounds, barrels, or bags per cubic yard.

Cement mixer

A concrete mixer. A container used to mix concrete ingredients by means of
paddles or a rotary motion. The container may be manually or power
-
operated.

Cement mixtures

Mixtures are always listed as parts Cement to Sand to Aggregate. Following are
typical cement mixtures description:



Rich

-

1 part cement, 2 parts sand, 3 parts coarse aggregate. A rich
mix is used for concrete roads and waterproo
f structures.



Standard

-

1 part cement, 2 parts sand, 4 parts coarse aggregate. A
standard mix is used for reinforced work floors, roofs, columns, arches,
tanks, sewers, conduits, etc.



Medium

-

1 part cement, 2 1/2 parts sand, 5 parts coarse aggregate.
A

medium mix is used for foundations, walls, abutments, piers, etc.



Lean

-

1 part cement, 3 parts sand, 6 parts coarse aggregate. A lean
mix is used for all mass concrete work, large foundations, backing for
stone masonry, etc.

Cement slurry

A thin, water
y cement mixture for pumping or for use as a wash over a surface.

Cement types



Type I Normal

-

is a general purpose cement suitable for practically all uses in
residential construction but should not be used where it will be in contact with high
sulfate s
oils or be subject to excessive temperatures during curing.



Type II Moderate

-

is used where precaution against moderate sulfate attack is
important, as in drainage structures where sulfate concentrations in groundwater's are
higher than normal.



Type III

High Early Strength

-

is used when high strengths are desired at very early
periods, usually a week or less. It is used when it is desirable to remove forms as soon
as possible or to put the concrete into service quickly.



Type IV Low Heat

-

is a special c
ement for use where the amount and rate of heat
generated during curing must be kept to a minimum. The development of strength is
slow and is intended in large masses of concrete such as dams.



Type V Sulfate Resisting

-

is a special cement intended for use

only in construction
exposed to severe sulfate action, such as western states having soils of high alkali
content.

Cementitious

Any material having cementing properties, usually referring to substances like
Portland cement and lime. See
Portland cement
.

Central plant

A facility that makes and distributes ready
-
mix or pre
-
mixed concrete loading
the material into agitator trucks. See
ready
-
mixed concrete

and
agitator trucks
.


Chair

A small metal or plastic support for reinforcing steel in concrete construction.
The support is used to maintain proper positioning during concrete placement.
See
bar support/bar chair

and
high chair
.

Cinder block

A masonry block made of crushed cinders and
Portland cement
. This type of
block is lighter and has a higher insulating value than concrete. Because
moisture causes deterioration of cinder block, it is used primarily for interior
rather tha
n exterior walls. See
concrete block
.

Clinker

The resulting admixture from burning a combination of limestone with silica,
alumina, and iron oxide
-
containing materials. A lump or ball of the f
used
material, usually 1/8" to 1" in diameter, is formed by heating cement slurry in
a kiln. Clinker, when cool, is ground into a fine powder and interground with
gypsum to form cement. See
admixture
.

Clip ties

Sharp, cut metal wires that protrude out of a concrete foundation wall (that at
one time held the foundation form panels in place).

Coarse aggregate

Naturally occurring, processed or manufactured, inorganic particles in
p
rescribed gradation or size range. The smallest size particle will be retained on
the No. 4 sieve.

Cold joint

A visible line that forms when the placement of concrete is delayed. The
concrete in place hardens prior to the next placement of concrete against

it.

Cold
-
rolled solid steel form pins

Concrete forming metal pins made from steel that has been rolled to its final
form at a temperature at which it is no longer plastic giving the pins a dense,
smooth, surface finish and high tensile strength. See
hot
-
rolled solid steel form
pins
.

Column clamp

A latching device for holding the sections of a concrete
-
column form together
while the concrete is being placed.

Colu
mn form

Specialized forms for creating low height columns typically used as parking lot
light anchors, communication tower bases, and similar applications where short
columns are required.

Compaction

The elimination of voids in construction materials, as i
n concrete, plaster, or
soil, by vibration, tamping, rolling, or some other method or combination of
methods. The process of eliminating voids in the non
-
set concrete mixture that
has been placed often using various vibration devices. A sister operation to

placing, compaction rates should be about equal to the time it takes to place.
See
placing

and
rod
ding
.

Composite construction

Any element in which concrete and steel, other than reinforcing bars, work as a
single structural unit. See
rebar
.

Compressive strength

The ability o
f a structural material to withstands squeezing forces. The
maximum compressive stress which material, Portland cement, concrete, or
grout is capable of sustaining.

Concrete

Concrete is a hardened building material created by combining a mineral
(which is
usually sand, gravel, or crushed stone) a binding agent (natural or
synthetic cement), chemical additives, and water. It is an excellent material to
be used in road building, bridges, airports, factories, waterways and other
construction projects. Concrete

is the mixture of Portland cement, sand, gravel,
and water used to make garage and basement floors, sidewalks, patios,
foundation walls, etc. It is commonly reinforced with steel rods (rebar) or wire
screening (mesh). See
binder
,
cement
,
Portland cement
, and
rebar
.


Concrete block

A concrete masonry unit, most often hollow, that is

larger than a brick. See
concrete masonry unit (CMU)
.

Concrete contraction

The shrinkage of concrete that occurs as it cures and dries. See
shrinkage
.

Concrete finish

A description of the smoothness, texture, or hardness of a concrete surface.
Floors are trowelled with steel blades to compress the surface into a dense
protective coat. See
trowel
,
troweling
, and
trowel finish
.

Concrete f
inishing machine

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. These machines are used to finish concrete
pavement
s. See
float

and
finishing
.

Concrete masonry unit (CMU)

A block of hardened concrete, with or with
out hollow cores, designed to be laid
in the same manner as a brick or stone. A CMU is also referred to as a concrete
block. See
concrete block
.

Concrete mixture

The percentage of cement conte
nt contained in the concrete. A rich mixture
contains a high proportion of cement. A lean mixture is a mixture of concrete or
mortar with a relatively low cement content. A harsh mixture of concrete is one
without mortar or aggregate fines, resulting in an

undesirable consistency and
workability. See
aggregate
,
cement
,
cement content/cement factor
,
cement
mixtures
,
cement types
.

Concrete transporting

The process of moving the concrete mix
ture from the central plant, or mixing
location, to the construction site. Transporting devices include agitator trucks,
buckets, wheelbarrows, conveyors, and pumping devices. See
agitator truck
.

Connector bolts

(1) Fastening devices used to connect forms and forming accessories. The
typical style is a slotted bolt with a locking wedge so concrete residue cannot
form on standard bolt.

(2) Bolts designed with vertical slots
used in conjunction with a small metal
wedge to attach two flatwork forms together during stacking use. See
flatwork
forms
,
flexible forms
,
stacking
, and
straight forms
.


Consistency

The degree of plasticity of fresh concrete or mortar. The normal measure of
consistency is
slump for concrete and flow for mortar. See
slump

and
slump
test
.

Consolidation

Compaction usuall
y 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 cons
truction joints
are placed horizontally or nearly horizontally.

Contractor

A person or company licensed to perform certain types of construction activities
that undertakes a legal obligation to perform specified construction work. Types
of contractors incl
ude:



General contractor

-

responsible for the execution, supervision and
overall coordination of a project and may also perform some of the
individual construction tasks. Most general contractors are not licensed
to perform all specialty trades and must h
ire specialty contractors for
such tasks, e.g. electrical, plumbing.



Remodeling contractor

-

a general contractor who specializes in
remodeling work.



Specialty contractor

-

licensed to perform a specialty task e.g.
electrical, side sewer, asbestos abatemen
t.



Sub contractor

-

a general or specialty contractor who works for
another general contractor.


Control joint

Tooled, s
traight grooves made on concrete floors to "control" where the
concrete should crack.

Corner forms

Metal concrete forms that are specialized forming accessories that are attached
to straight forms to form 90° corners. Typical applications for corner forms

include patios, sidewalks, warehouse floors, slab on grade house foundations,
and similar flatwork applications. See
slab on grade

and
straight forms
.


Cream

Construction slang term to describ
e the cement and sand component of ready
-
mix that rises when the aggregate is worked down by way of agitation


floating, troweling, screeding, etc. This is also referred to as "juice". See
float
,
floating
,
ready
-
mixed concrete
,
screed
,
screeding
,
trowel
, and
troweling
.

Curb and gutter

The border area of a street, or other paved surface, that includes a curb, an
extruded or hand
-
formed berm, and a gutter, the area designed to remove and
transport water awa
y from the main paved area. Both parts are usually made
out of concrete. See
curb and gutter combination

and
curb and g
utter forms
.

Curb and gutter accessories

Forming components, specialized tools, and attachments that are used to
facilitate curb and gutter placement and include
hangers
,
bracing
,
stake
pullers
,
filler forms
,
form stakes
,
form pins
, and
curbface mules
.

Curb and gutter combination

Refers to curbs and gutter combinations that are formed in the same concrete
pour. The curb portion varies from 4" to 12" in height and is used to prevent
vehicles from leaving a paved area. T
he gutter portion varies from 6" to 12" in
width and is used to control water runoff from pavement. The elevation of the
gutter is either slightly above, or slightly below, the grade of the pavement.
Additionally, the gutter itself will have a slight inwar
d or outward slant to direct
the flow of water either towards or away from the curb, dependent on the
desired water flow. See
pouring
,
pitch
-
in
, and
pitch
-
out
.

Curb and gutter face forms

Metal forms used in placing concrete that attach to the curb and gutter system
to form
the profile for the curbface.


Curb and gutter forms

Concrete forms and accessories used to pour a curb and gutter combination.
The curb and gutter forming systems consis
ts of a back form, a face form, a
front form, a division plate and a top spreader. Back and front forms are
standard straight forms with the back form taller than the front form for a curb
and gutter combination configuration. See
division plate
,
straight forms
, and
top spreader
.

Curbface batter

Curbface batter refers to the distance between the top slope of a curbface and
the bottom slope of a curbface. See
batter
.


Curbface mule

A mechanical tool used to form the desired curb profile for any curb and gutter
application. See
curb and gutter forms
.

Curbface tool

A hand tool made to match the profile of the curbface used to finish and
smooth the curbface after concrete placement, but before concrete hardening.
See
mule
.


Curbface transition forms

Curbface transition forms allow a contractor to quickly change from a straight
to a radius curb and back to a s
traight curb. They usually come in male/female
pairs.


Cure

Method of maintaining sufficient internal humidity and proper temperature for
freshly placed conc
rete to assure proper hydration of the cement, and proper
hardening of the concrete. See
hydration
.

Curing

The hardening of concrete, plaster, or other wet material. Curing ty
pically
occurs through the evaporation of water or a solvent, hydration,
polymerization, or chemical reactions of various types. It is the final process,
after placing and compacting, that ensures the concrete will set to its desired
strength. The length o
f time is dependent upon the type of cement, mix
proportion, required strength, size and shape of the concrete section, weather
and future exposure conditions. The period may be 3 weeks or longer for lean
concrete mixtures used in structures such as dams o
r it may be only a few days
for richer mixes. Favorable curing temperatures range from 50° to 70° F.
Design strength is achieved in 28 days. See
cement mixture
,
compaction
,
hydration
, and
set
.

The American Concrete Institute defines

curing as maintaining satisfactory
moisture content and temperature in concrete during its early stages so that it
may obtain the desired properties. See
placing

and
compaction
.

Curing blanket

A layer of straw, burlap, sawdust, or other suitable material placed over fresh
concrete and moistened to help maintain humidity and temperature for proper
hydration. See
burlap
,
curing
,
curing compound
, and
curing membrane
.

Curing compound

A chemical applied to the surface of fresh concrete to minimize the loss of
moisture during the first stages of setting and hardening. See
curing
,
curing
membrane
, and
curing blanket
.

Curing membrane

Any of several kinds of sheet material or spray
-
on coatin
gs used to temporarily
retard the evaporation of water from the exposed surface of fresh concrete,
thus ensuring a proper cure. See
burlap
,
curing
,
curing compound
, and
curing
blanket
.

Custom forms

A variety of unique forms used for specialized conc
rete forming such as
reversible forms
,
super flat forms
,
tilt
-
up forms
,
tilt
-
up reversible forms
,
foundation set forms
,
seawall forms
,
rehab forms
, and
column forms
.

Cut and fill

A term used to describe the addition or subtraction from a grade mark. Also, an
operation commonly used in road building and other rock and earthmoving
operations in whic
h the material excavated and removed from one location is
used as fill material at another location.






Dampproofing

A process used on concrete, masonry or stone surfaces to repel water, the
main purpose of which is to prevent the coated surface from abs
orbing rain
water while still permitting moisture vapor to escape from the structure.
(Moisture vapor readily penetrates coatings of this type.) "Dampproofing"
generally applies to surfaces above grade; "waterproofing" generally applies to
surfaces below g
rade.

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.
See
screed

and
float
.

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. See
slurry
.

Division plate

A concrete forming accessory used to create a break in a concrete sidewalk or
curb and gutter. This engineered br
eak 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 div
ision 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. See
dowel

and
rebar
.

Division plate (skeleton)

Skeleton division plates are used to support the curbface form and add support
for the curb and gutter system. See
curb face form
.


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 w
ill stay exactly where it is
positioned into a curb and gutter placement, eliminating problems with the final
rebar positioning.







DOT

The acronym for the Department of Transportation.

Dowel

A cylindri
cal piece of stock inserted into holes in adjacent pieces of material to
align and/or attach the two pieces. See
rebar

and
reinforced concrete
.

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. See
dowel
,
rebar
,
and
reinforced concrete
.

Dowel lubricant

A lubrican
t applied to dowels placed in adjoining concrete slabs to allow
longitudinal movement in expansion joints. See
dowel
,
expansion joint
, and
rebar
.

Dowel screw

A threaded dowel. See
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. See
heat of
hydration
.

Dry pack

A low
-
slump grout tamped into the space in a connection between pre
-
cast
concrete members. See
slump

and
pre
-
cast concrete
.

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 befo
re the
concrete has set and then troweling it in. See
shake
-
on hardener

and
troweling
.

Drying shrinkage

Contraction caused by the loss of moisture, particularly in concrete, mortar,
and plaster. See
shrinkage
.





Edger (edging trowel)

A tool used to fashion fin
ishing edges or round corners on fresh concrete or
plaster. See
trowel
,
troweling
,
trowel finish
.

Edging trowel

See
edger
.

Efflorescence

The process by which water leeches soluble salts out of concrete or mortar a
nd
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 for
ces induced by pre
-
stressing. See
pre
-
stressed concrete
.

End plugs

Heavy
-
gauge metal cap ends for the straight steel forms.



Expansion joint

A surface divider joint that provides space for the s
urface 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 fro
m expansive cement for the purpose of reducing or
controlling volume changes that occur during curing. See
curing
.

Exposed aggregate

See
Aggregate, exposed
.

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 o
ther exterior surfaces. See
Aggregate, exposed
.

Extension chute

An additional chute used by a concrete contractor to extend the length of the
existing chutes from a rea
dy
-
mix concrete truck. They are frequently used to
pour floors. See
agitator truck

and
ready
-
mixed concrete
.

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 att
aches 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. See
batter
,
curb and gutter combination
, and
curb and gutter forms
.

Faced concrete

To finish the front and all vertical sides of a concrete porch, st
ep(s), or patio.
Normally the "face" is broom finished. See
broom finish
.

Fair face concrete

A concrete surface that, on completion of the forming process, requires no
addi
tional (concrete) treatment other than curing. See
architectural concrete

and
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 the addition of water. Premature
stiffen
ing, and rubber set are terms referring to the same phenomenon, but
false set is the preferred term. See
flash set
,
Portland cement
, and
set
.

Fat

Material accumulating on a trowel during smoothing. Fat is used to fill in small
imperfections. See
trowel

and
troweling
.

Fat mix / rich mix

A mortar or concrete mix with a relatively high cement content. Fat mix is more
easily spread and wor
ked than a mix with the minimum amount of cement
required for strength. See
cement

and
cement

mixture
.

Fiber reinforced concrete

A variant of concrete that is produced by adding fibers made of stainless steel,
glass or carbon to the mixture. See
reinforced c
oncrete
.

Fibrous admixture

Special fibrous substances of glass, steel, or polypropylene that are mixed into
concrete to act as a reinforcement against plastic shrinkage cracking.


Filler forms

Concrete forming accessories used to connect two metal forms when a gap
between the forms exists. Typically, filler forms have a channel that slides over
the top rail of the forms t
o be connected. See
straight forms
.


Fine aggregate

Aggregate passing the

1/2" sieve

and almost entirely passing the No. 4 sieve
and predominantly retained on the No. 200 sieve.

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 inch, 3/4 inch, 1

inch, 2 inch, 3 inch, and 6 inch.

Finishing

Leveling, smoothing, compacting, and otherwise treating surfaces of fresh or
recently placed concrete or mortar to produce the desired appearance and
service. See also
float
.

Fixed nose form

A metal concrete pouring form with a fixed nose piece to allow it to interlock
with the rear section of another form creating a solid interconnection. Fixed
nose forms must be removed in order or reverse order after a pou
r due to their
interlocking nature. See
sliding nose forms
.

Flash set

The rapid development of rigidity in a mixed Portland cement paste, mortar or
concrete usually w
ith 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. See
false set
.

Flat stakes

Flat metal stakes used to secure wooden forms in sandy or loose soils prior to
concrete placement. See
curb and gutter forms
,
form pins
,
flatwork forms
, and
nail stakes
.


Flatwork

Common word for concrete floors, driveways, basements, and sidewalks.

Flatwork forms

Metal or wood forms used in concrete flatwork placement. These forms are
typically used for e
dge forming, sidewalks, driveways, footings, industrial slabs,
foundations, patios, general flatwork, and in combination with our curb and
gutter accessories, plus concrete curb and gutter work. See
curb and gutter
forms
,
flexible forms
, and
straight forms
.

Flexible forms

M
etal forms used forming radius shapes such as islands, serpentine sidewalks,
curved curbs, parking lot turnouts, and similar applications. They are made
from spring steel and are typically 10 feet long with stake pockets riveted onto
the form every 18". Th
ey range in height form 4" to 12". The same as radius
forms. See
spring steel
.

Flexible filler forms

A flatwork form accessory used to fill in spans of less than 10' where
radius
forming is required. These forms are sometimes referred to as rehab forms.
See
flatwork forms
,
flexible forms,

and
straight forms
.

Float

A tool (not a darby), usually of wood, aluminum, magnesium, rubber, or
sponge, used in concrete or tile finishing operations to impart a relatively even
but still open texture to an unformed fresh concrete surface. See
darby

and
trowel
.

Float coat

A fini
sh coat of cement paste applied with a float. See
float
.

Floating

The next
-
to
-
last stage in concrete work, when you smooth off the job and bring
water to the surface by using a hand float or bull float
. The operation of
finishing a fresh concrete or mortar surface by use of a float, preceding
troweling when that is the final finish. See
troweling
,
float
, and
float coat
.

Floating wall

A non
-
bearing wall built on a concrete floor. It is constructed so that the
bottom two horizontal plates can compress or pull apar
t if the concrete floor
moves up or down. A floating wall is normally built on basements and garage
slabs.

Flow
-
line

The section of a pitch
-
in curb where water flows in a parallel direction. See
pitch
-
in
.

Fly ash

A byproduct produced by coal
-
burning power plants that contains
aluminosilicate and small amounts of lime. When combined with lime in a
hydrothermal (using hot water under pressure) process, cement can be
produced. It is

a concrete admixture. See
admixture
.


F
ooting

The widened portion of the foundation or a structure that spreads and
transmits the load from the building or foundation directly to, and across a
broader area of, the soil. A continuous 8" or 10" thick concrete pad installed
before that supports th
e foundation wall or monopost.

Form

A temporary erected structure or mold for the support and containment of
concrete during placement and while it is setting and gaining sufficient strength
to be self
-
supporting.

See
corner forms
,
formwork
,
filler forms
,
flexible forms
,
keyway forms
,
placement
,
radius forms
,
reversible forms
,
stra
ight forms
,
slurry
,
tilt
-
up forms
,
tilt
-
up reversible forms
, and
transition forms
.

Form hanger

A device used to support formwork from a structural framework. The dead
load
of forms, weight of concrete, and construction and impact must be supported.
See
formwork
.

Form pins

Solid steel pins made from either

cold
-
rolled and hot
-
rolled steel used for
securing metal flatwork forms to the ground by driving the pins through wedge
pockets and for attaching screed bar holder clamps used flatwork finishing.

Pins are typically 1/2" or 7/8" in diameter and vary in le
ngth from 12" to 48" or
more depending on the project requirements.

See
cold
-
rolled solid steel form pins
,
flat stakes
,
flatwork forms
,
flexible forms
,
hot
-
rolled solid steel form pins
,
nail stakes
, and
screed bar hol
der
.

Form rail

The top edge of a straight form that runs the length of the form and is typically
2 inches wide for most standard forms. Often, form rails are used as guides
and supports for screeding. See
screeding

and
straight forms
.

Form release agent or compound

Material used to prevent bonding of concrete to a surface, such as to forms.
S
ee
bond breaker
,
stripping agent
, and
release agent
.

Form scabbing

The inadvertent removal of the surface of concrete as a result of adhesion to
the form.

Form stakes

See
form pins
.

Forming

The use

of metal or wood forms to create the proper placement of concrete.
The forming process channels the concrete into the desired shape and
thickness.

See
corner forms
,
filler forms
,
flexible forms
,
keyway forms
,
placement
,
radius
forms
,
reversible forms
,
straight forms
,
slurry
,
tilt
-
up forms
,
tilt
-
up reversible
forms
, and
transition forms
.

Formwork

Temporary structures or forms made of wood, metal, or plastic used in the
placing of concrete to ensure the slurry is shaped to its desired final form.
Formwork must be strong enough to support the considerabl
e weight and
pressure of wet concrete without deflection.

See
corner forms
,
filler forms
,
flexible forms
,
keyway forms
,
placement
,
radius
forms
,
reversible forms
,
straight forms
,
slurry
,
tilt
-
up forms
,
tilt
-
up reversible
forms
, and
transition forms
.

Foundation

The entire masonry substructure below the

first floor or frame of a building,
including the footing upon which the building rests.

Foundation form sets

Custom made sets of metal concrete forms used for houses, garage, car port,
strip mall, warehouse floors, and other structures which require slab

on grade
foundations. See
custom forms

and
foundation
.

Foundation ties

Metal wires that hold the foundation wal
l panels and rebar in place during the
concrete pour.

Foundation waterproofing

A high
-
quality below
-
grade moisture protection. It is used for below
-
grade
exterior concrete and masonry wall damp
-
proofing to seal out moisture and
prevent corrosion. Foundatio
n waterproofing normally looks like black tar.

Frame


The setting up of formwork. See
formwork
.





General contractor

A contractor who enters into a contract with the owner of a project for the
co
nstruction of the project and who takes full responsibility for its completion,
although the contractor may enter into subcontracts with others for the
performance of specific parts or phases of the project. See
contractor
.

Glass Fiber Reinforced Concrete (GFRC)

Material used in wall systems that resembles but generally does not perform as
well as concrete. It usually is a thin cementitious material laminated to plywood
or oth
er lightweight backing.

Grade

The surface or level of the ground. The existing or proposed ground level or
elevation on a building site or around a building. The slope or rate of incline or
decline of a road, expressed as a percent. A designation of a sub
floor, either
above grade, on grade, or below grade. Any surface prepared to accept paving,
conduit, or rails. See
line
.

Grade line

A strong string used to establish the top of a c
oncrete placement.

Grout

A high
-
slump mixture of Portland cement, aggregates, and water which can be
poured or pumped into cavities in concrete or masonry for the purpose of
embedding reinforcing bars, and/or increasing the amount of load
-
bearing
material
in a wall. See
aggregate
,
Portland cement
,
rebar
, and
slump
.

Gunite

A term sometimes used to designate dry
-
mix shotcrete. See
shotcrete
.





Hand float

A wooden tool used to lay on and to smooth or texture a finish coat of plaster
or concrete. See
float
,
trowel

and
darby
.

Hangers

A straight metal bar with pockets on an
adjustable slide that allow straight
forms to be placed in areas where securing forms into position is difficult due to
soil conditions, existing pavement, or obstacles.

Hangers are often used in applications such as sidewalks, foundations, and curb
and g
utter work. See
straight forms
.



Hardener

The curing agent of a two
-
part synthetic resin, adhesive, or similar coating. See
curing
.

Haunch

An extension, a knee like protrusion of the foundation wall that a concrete
porch or patio will rest upon for support.

Heat of hydration

The thermal energy, or heat, resulting from chemical reactions with wat
er, as
in the curing of Portland cement, concrete, or gypsum, as it cures. See
concrete
,
curing
,
hot load
, and
Portland cement
.

High chair

Slang for a heavy, wire, vaguely chair
-
shaped device used to hold stee
l
reinforcement off the bottom of the slab during the placement of concrete. See
bar chair

and
ch
air
.


High
-
pressure steam curing (autoclave curing)

The steam curing of products made from cement, sand
-
lime, concrete,

or
hydrous calcium silicate in an autoclave at temperatures of 340° to 420° F.

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.

Hon
eycomb

A method by which concrete is poured and not puddled or vibrated, allowing
the edges to have voids or holes after the forms are removed. An area in a
foundation wall where the aggregate (gravel) is visible. Honeycombs can be
usually be remedied by a
pplying a thin layer of grout or other cement product
over the affected area. See
aggregate

and
vibration
.

Hot load

Construction slang used to describe ready
-
mix concrete that has begun its
hydration process while still in the delivery drum of the agitator truck.
Hydration causes heat build up in the concrete mix. See
ready
-
mixed concrete
,
hydration
,
heat of hydration
, and
agitator truck
.

Hot
-
rolled solid steel form pins

Concrete forming metal pins that were formed by rollers from a hot plastic
state into its final shape. Hot rolled pins are characterized by

a rough, scaly
surface and do not contain the tensile strength of cold
-
rolled steel pins. See
cold
-
rolled solid steel form pins
.

Hydration

The chemical reactio
n that occurs when cement is mixed with water. See
hot
load

and
heat of hydration
.

Hydraulic cement

A variety of cement engineered to

harden under water. See
air
-
entrained
agent
.





Initial set

A degree of stiffening of the cement and water mixture. This is a degree less
than final set and is gener
ally 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. See
false
set
,
flash set
, and
set
.

Initial stress

In pre
-
stressed c
oncrete, the stresses occurring in the pre
-
stressed members
before any losses occur. See
pre
-
stressed concrete
.





Jacking equipment

The device used to stress the
tendons

in pre
-
stressed concrete. See
pre
-
stressed concrete
.

Jitterbug

A grate tampe
r used to cause sand and cement grout to rise to the surface of
wet concrete during placement of slabs. May be motorized or hand operated.
See
tamper
.

Joint

Position where two o
r more building materials, components or assemblies are
put together, fixed or united, with or without the use of extra jointing products.
The location between the touching surfaces of two members or components
joined and held together by nails, glue, ceme
nt, mortar, or other means.

Juice

See
cream
.




Kelly ball

A device for determining the consistency of fresh concrete. It is sometimes
used as an alternative to the slump test. S
ee
slump
,
slump cone
, and
slump
test
.

Key

A slot formed into a concrete surface for the purpose of interlocking with a
subsequent pour of concrete.

Keyway

A recess or groove in one lift or placement of concrete that is filled with
concrete of the next lift, giving shear
strength to the joint. Also called a
key
.

Keyway attachments

A ten
-
foot long keystone
-
shaped metal concrete forming accessory that
attaches to standard metal forms used to create horizontal tongue and gr
oove
connections for all types of floors and slabs. See
flatwork forms

and
straight
f
orms
.

Keyway forms

Metal concrete forming devices used to pour interconnecting slabs. They are
basically standard straight forms with holes drilled along the center face onto
which a keyway is bolted and then used to pour "keyed" slabs. When the
straight
forms are needed for a standard pour, the keyway attachment is easily
removed. See
straight forms
.


Kiln

A furnace, oven, or heated enclosure for drying (wood), or charring, hardening,
baking, calcining, sintering, or burning various materials. A furnace for firing
clay
or glass products or a heated chamber for seasoning wood.

Knee boards

Boards used by concrete finishers to kneel on to perform hand trowel flatwork.
See
trowel

and
troweling
.






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.
See
bleeding
.

Lateral force

A force acting in a generally horizontal direction, such as wind, earthquake, or
soil pressure against a foundation wall.

Lift

A layer of concrete.

Lift
-
slab construction

A building method for multi
-
story sitecast concrete buildings that casts all the
slabs in a stack on the ground and then lifts them up the columns and welds
them into place. See
sitecast concrete
.

Line

A rope or string made of nylon used as a guide to set forms to grade. See
grade
.

Lock clamps

Accessory clamps used to con
nect transition forms to flexible forms used in all
flatwork and curb and gutter applications. See
curb and gutter forms
,
flatwork
forms
,
flexible forms
, and
transit
ion forms
.


Long float

A concrete finishing float designed to be handled by two men. See
float
.

Low
-
lift grouting

The common and simple method of unifying concrete masonry, in which the
wall sections are built to a height of not more than 4" before the cells of the
masonry units are filled with grout.





Magnetite

An aggregate used in heavy

weight concrete, consisting primarily of ferrous
metaferrite (Fe 304). A black magnetic iron ore with a specific gravity of
approximately 5.2 and a Mohs hardness of about 6. See
aggregate
.

Mason

One who builds with brick, stones, concrete masonry units, or concrete. See
concrete masonry units

and
concrete
.

Masonry

Construction composed of shaped or molded units, usually small enough to be
handled by one man and composed of stone, ceramic brick, or tile, concrete,
glass, adobe, or the like. The term masonry is sometimes used t
o designate
cast
-
in
-
place concrete
.

Masonry cement

A mill
-
mixed mortar to which sand and water must be added. A Portland
cement with dry admixtures designed to incr
ease the workability of the mortar.
See
Portland cement
.

Mass concrete

Any volume of concrete with dimensions large enough to require that measures
be taken to cope with

generation of heat from hydration of the cement and
attendant volume change, to minimize cracking. See
heat of hydration
.

Maturing

The curing and hardening of construct
ion materials such as concrete, plaster,
and mortar. See
curing
.

Maul

A heavy mallet with an oversized wooden head used for driving wood takes,
pegs, or wedges into the ground o
r in other applications where material might
sustain damage if struck with a conventional sledgehammer. It is also referred
to as a "beetle".

Maximum size aggregate

Aggregate whose largest particle size is present in sufficient quantity to affect
the phys
ical 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.


Membrane curing

A process of controlling the curing of concrete by sealing in the moisture that
would be lost to evaporation. The process is accomplished either by spraying a
sealer on the surface or by covering the surface
with a sheet film.

Mix

A general term referring to the combined ingredients of concrete or mortar.
Examples might be a five
-
bag mix, a lean mix, or a 3,000
-
psi mix. See
concrete mixture
.

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 b
atch; 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 a 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.

Monolithic

A plain or reinforced mass of concrete cast
as a single, one piece, integral
structure.

Monolithic surface treatment

A concrete finish obtained by shaking a dry mixture of cement and sand on a concrete
slab after strike
-
off, then troweling it into the surface. See
strike off

and
troweling
.

Mortar

A mixture of cement (or lime) with sand and water used in masonry work.

Mortar board

A mason's
hand tool used to hold small amounts of material that is typically
being applied to a vertical surface with a hand trowel. It is often used in
patching and finish work. The mortar board is a square flat piece of wood or
metal with a handle placed in its ce
nter on the bottom side.

Mud

Slang term for cement or mortar.

Mud slab

A base slab of low
-
strength concrete from 2" to 6" thick placed over a wet
subbase before placing a concrete footing or grade slab.

Mule

A hand
-
held or machine mounted device used to s
hape concrete by dragging or
pressing it over the form boards. This device is commonly used in curb and
gutter work. See
curb and gutter
.

Mushroom

The unacceptable occurrenc
e when the top of a caisson concrete pier spreads
out and hardens to become wider than the foundation wall thickness. See
caisson
.





Nail stakes

Round steel pins used to fast
en wood forms together and securing them to the
ground by pounding nails through pre
-
drilled holes in the pins.

They are commonly used in all flatwork applications and for attaching screed
bar holder clamps in flatwork finishing. They typically are made i
n 1/2" or 7/8"
diameters and come in lengths form 12" to 48".

See
cold
-
rolled solid steel form pins
,
form pins
,
flat stakes
,
flatwork forms
, and
hot
-
rolled solid steel form pins
.



Neat cement

Unhydrated hydraulic cement. See
hydraulic c
ement
.

Neat cement
-
paste

A mixture of water and hydraulic cement, both before and after setting and
hardening. See
hydraulic cement
.

No
-
fines concrete

A concrete mix
ture in which only the coarse gradation (3/8" to 3/4" normally)
of aggregate is used. See
aggregate
.

Non
-
agitating unit

A truck
-
mounted unit for transporting ready
-
mixed concr
ete short distances,
but not equipped to provide agitation (slow mixing) during delivery. See
agitator truck

and
ready
-
mixed concrete
.

Non
-
air
-
entrained concrete

Concrete in which neither an air
-
entraining admixture nor air
-
entraining cement
has been used. See also
air
-
entrained agent
,
admixture
, and
air
-
entrained
concrete
.






Ot
tawa sand

Sand used as a standard in testing hydraulic cements by means of mortar test
specimens. This type of sand is produced by processing silica rock particles
obtained by hydraulic mining of the orthoquartzite situated in open
-
pit deposits
near Ottaw
a, Illinois; naturally rounded grains of nearly pure quartz. See
hydraulic cement
.

Outside radius

The formed outside radius of a bend.

Overvibration

Excessive use of vi
brators during placement of freshly mixed concrete, causing
segregation and excessive bleeding. See
bleeding

and
segregation
.





Parging

Portland cement plaster applied over masonry to make it less permeable to
water.

Particle
-
size distribution

Particle distribution of granular materials among various sizes; for concrete
material normally design
ated as gradation. It is 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.

Paver, paving

Materials, typically masonry, that are laid down
to make a firm, even surface.

Paving forms

Heavy duty metal forms used in the placement of concrete for concrete
roadways, commercial driveways, intersection entrance and exit ramps, and
airport work. See
apron
.

Paving machine

A self
-
propelled piece of construction equipment that forms and finishes
concrete simultaneously. See
slip form
.

Pea gravel

P
ortion of concrete aggregate passing the 1/2" sieve and retained on a No. 4
sieve.

Peeling

A process in which thin flakes of matrix or mortar are broken away from the
concrete surface. It is caused by adherence of surface mortar to forms as forms
are remo
ved, or to trowel or float in Portland cement plaster. See
concrete
,
forming
,
float
,
trowel
, and
Portland cement
.

Pining

The developm
ent of relatively small cavities in a concrete surface due to
phenomena such as cavitation or corrosion.

Pitch

The amount of angle or slope used in concrete flatwork to disperse water. See
slope
.

Pitch
-
in

A curb and gutter profile designed to accept water into the flow
-
line of the
gutter. It is also referred to as wet
-
curb. See
flow
-
line

and
pitch
-
out
.

Pitch
-
out

A curb and gutter profile designed to direct water away form the curb. It is also
known as a dry
-
curb or spill
-
out curb. See
flow
-
line

and
pitch
-
in
.


Placement

The process

of placing and consolidating concrete. A quantity of concrete
placed and finished during a continuous operation. Also, inappropriately
referred to as pouring. See
placing
.

Placing

The physical inser
tion of the concrete mixture into the final location avoiding
segregation of the mixture materials and compaction can be achieved. The
deposition, distribution, and consolidation of freshly mixed concrete in the place
where it is to harden. Also, inappropr
iately referred to as pouring. See
compaction

and
placement
.

Plain concrete

Concrete either without reinforcement,

or reinforced only for shrinkage or
temperature changes. See
shrinkage
.

Plant mix

A mixture of aggregate and asphalt cement or liquid asphalt, prepared in a
central or travel
ing mechanical mixer. Any mixture produced at a mixing plant.
See
agitator truck
,
centr
al plant
,
concrete transporting
, and
ready
-
mixed
concrete
.

Plastic consi
stency

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

An agent used to increase the fluidity of fresh cement with the same
cement/water ratio improving the workability and placement of the cement.
Same as a superplasticizer.

Pocket

See
stake pocket
.

Polyethylene

A thermoplastic widely used in sheet form for vapor retarders, moisture
barriers, and temporary construction coverings. See
Visqueen
.

Portland cement

A special synthetic blend of limestone and clay used to make concrete which is
generally believed to be stronger, more durable, and more consistent than
concrete made from natural cement. Portland cement is made by mi
xing
calcareous material, like limestone, with silica, alumina, and iron oxide
-
containing materials. These materials are burned together and the resulting
product, or admixture, is ground up to form Portland cement. See
cement

and
concrete
.

Posttensioning

A method of pre
-
stressing reinforced concrete in which tendons are tensioned
after the concrete ha
s hardened. See
pre
-
tensioning
.

Pour

To cast concrete. A pour is an increment of concrete casting carried out without
interruption. See
casting
.

Power float

See
rotary float
.

Pozzolano (ASTM C 618)

A siliceous, or siliceous and aluminous material, which in itself possesses little
or n
o 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.


Pre
-
cast concrete

Concrete forms cast into permanent shapes using reusable forms at a plant,
then transported as fully

cured structural units to the actual construction job
site. See
cast
-
in
-
place concrete
.

Pre
-
mixed concrete

The same as
ready
-
mixed concrete
.

Pre
-
placed aggregate

Coarse aggregate placed in a form, with Portland cement grout injected later.
See
aggrega
te

and
Portland cement
.

Pre
-
placed concrete

Concrete manufactured by placing clean, graded coarse aggregate in a form
and later injecting a Portland cement
-
sand grout under pressure, to fil
l the
voids.

Pre
-
stressed concrete

Concrete that has already been subjected to compression increasing its ability
to withstand tension and stress without the need for steel reinforcement.
Concrete in which internal stresses of such magnitude and distributi
on are
introduced that the tensile stresses resulting from the service loads are
counteracted to a desired degree. In reinforced concrete, the pre
-
stress is
commonly introduced by tensioning the
tendons
. See
reinforced concrete
.

Pre
-
stressed concrete wire

Steel wire with a very high tensile strength, used in pre
-
stressed concrete. The
wire

is initially stressed close to its tensile strength. Then some of this load is
transferred to the concrete, by chemical bond or mechanical anchors, to
compress the concrete. See
pre
-
stre
ssed concrete
.

Pre
-
tensioning

The compressing of concrete in a structural member by pouring the concrete
for the member around stretched high
-
strength steel strands, curing the
concrete, and releasing the external tensioning force on the strands. See
posttensioning
.

Proportioning

The selection of proportions of material for concrete to make the most
economical use of available materials to manufacture concrete of the required
strength, place
ability, and durability.

Pump mix

Special concrete used in a concrete pump. Generally, the mix has smaller rock
aggregate than regular concrete mix. See
aggregate
.

Punched for
dowel forms

Metal concrete placement forms with dowel holes punched into them to hold
either solid dowels or rebar to reinforce the concrete placement. See
dowels
,
rebar
,
reinforced concrete
, and
paving for
ms
.





Radius (steel) forms

Metal forms used forming radius shapes such as islands, serpentine sidewalks,
curved curbs, parking lot turnouts, and similar applications. See
flexible forms
.

Reactive aggregate

Aggregate containing substances capable of reacting chemically with the
products of solution or hydration of the Portland cement in concrete or mortar,
under ordinary conditions of exposure, resulting in harmful expa
nsion,
cracking, or staining.

Ready
-
mixed concrete

Concrete that is batched or mixed at a central plant before it is delivered to a
construction site and delivered ready for placement. It is also known as transit
-
mixed concrete since it is often transporte
d in an agitator truck. See
agitator
truck
.

Rebar

The reinforcing bar
-
ribbed steel bars installed in foundation concrete walls,
footers, and poured in place concrete stru
ctures designed to strengthen
concrete. Rebar comes in various thickness' and strength grade. The term
rebar is short for reinforcing bar.

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.

Rehab forms

Light
-
weight extend angle
-
iron
-
shaped metal forms, often 10' long with a 2' top
rail and no bottom rail, used to replace sections of sidewalk without extens
ive
excavation of surrounding soil. Rehab forms slip into place and are anchored
into place with stakes after removal of the damaged concrete.

Reinforced concrete

Concrete reinforced by the addition of steel bars making it more able to
tolerate tension and

stress. See
pre
-
stressed concrete
.


Release agent

Material used to prevent bonding of concrete to a surface, such as to forms.
See
bond breaker
,
form release agent
.

Retempering

The addition of water and remixing of concrete which has started to stiffen.
This is usually not allowed as it may affect the ultimate strength.

Reversible forms

A formed metal channel th
at is a combination of two sizes of straight forms. A
90° angle is formed which each leg having a different height. This type of form
is used when a concrete contractor needs to pour two slabs of different heights.
One side of the form might have a height
of 10" and the other side might have
a height of 14". This variation allows the one set of forms to be used to pour
two different slabs. See
straight forms
.

Revibration

Delayed vibration of concrete that has already been placed and consolidated.
This is most effective when done at the latest time a running vibrator will sink