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 Bag
(of cement) (See Sack)
Barrel (of cement) A unit of weight for cement: 376 Ibs net,
equivalent to 4 US bags of portland cement. The designation presently
used is tons of cement.
Blaine Fineness The fineness of granular materials such as cement
and pozzolan, expressed as total surface area in square centimeters per
gram, determined by the Blaine air-permeability apparatus and procedure.
Blast Furnace Slag A non-metallic waste product developed in the
manufacture of pig iron, consisting basically of a mixture of lime,
silica and alumina, the same oxides that make up portland cement, but
not in the same proportions or forms. It is used both in the
manufacture of portland blast furnace slag cement and as an aggregate
for lightweight concrete.
Bleeding, Bleed Water A form of segregation in which some of the
water in a mix tends to rise to the surface of freshly placed concrete.
Known also as water gain.
Bond Adhesion of concrete or mortar to reinforcement, or to other
surfaces. The adhesion of cement paste to aggregate.
Bush-hammer A tool having a serrated face, as rows of pyramidal
points, used to develop an architectural finish for concrete surfaces.
Calcareous Containing calcium carbonate or, less
generally, containing the element calcium.
Calcine To alter composition or physical state by heating to a
specific temperature for a specific length of time.
Calcium Aluminate Cement The product obtained by pulverizing clinker
consisting essentially of hydraulic calcium aluminates resulting from
fusing or sintering a suitable proportioned mixture of aluminous and
calcareous materials.
Capillarity A wick-like action whereby a liquid will migrate
vertically through material, in a upward direction; as oil in a lamp
travels upward through the wick,
Capillary Space In cement paste, any space not occupied by anhydrous
cement or cement gel. Air bubbles, whether entrained or entrapped, are
not considered as part of the cement paste.
Carbonation 1) Reaction between the products of portland cement
(soluble calcium hydroxides), water and carbon dioxide to produce
insoluble calcium carbonate (efflorescence). 2) Soft white, chalky
surface dusting of freshly placed, unhardened concrete caused by carbon
dioxide from unvented heaters or gasoline powered equipment in an
enclosed space. 3) Carbonated, dense, impermeable to absorption, top
layer of the surface of concrete caused by surface reaction to carbon
dioxide. This carbonated layer becomes denser and deeper over a period
of time. 4) Reaction with carbon dioxide which produces a slight
shrinkage in concrete. Improves chemical stability. Concrete masonry
units during manufacturing may be deliberately exposed to carbon dioxide
after reaching 80% strength to induce carbonation shrinkage to make the
units more dimensionally stable. Future drying shrinkage is reduced by
as much as 30%.
Cellular Concrete A lightweight product consisting of portland
cement, cement-pozzolan, cement sand, lime-pozzolan, or lime-sand
pastes, or pastes containing blends of these ingredients and having a
homogenous void or cell structure, attained with gas forming chemicals
or foaming agents. For cellular concretes, containing binder ingredients
other than or in addition to portland cement, autoclave curing is
usually employed.
Cement, Portland (ASTM C150) A powdery substance made by burning,
at a high temperature, a mixture of clay and limestone producing lumps
called “clinkers” which are ground into a fine powder consisting of
hydraulic calcium silicates. For non-portland cements, see aluminous
cement.
Cement Content A quantity of cement contained in a unit volume of
concrete or mortar, ordinarily expressed as pounds, barrels, or bags per
cubic yard.
Cement Gel The colloidal gel (glue like) material that makes up the
major portion of the porous mass of which hydrated cement paste is
composed.
Cementitious Having cement-like, cementing, or bonding type
properties. Material or substance producing bonding properties or
cement-like materials.
Chair(s) In concrete formwork, the support for the reinforcing
steel.
Change of State The process whereby liquid is heated to the point of
evaporation changing the liquid into a gas the condensation of a gas on
a cooler surface returning it from gaseous to liquid form.
Coarse Aggregate Naturally occurring, processed or manufactured,
inorganic particles in prescribed gradation or size range, the smallest
size of which will be retained on the No. 4 (4.76 mm) sieve.
Coefficient of Thermal Expansion Change in unit length per degree
change of temperature.
Cold Joint A visible lineation which forms when the placement of
concrete is delayed. The concrete in place hardens prior to the next
placement of concrete against it.
Colloidal A gel-like mass which does not allow the transfer of ions
Compressive Strength The measured resistance of a concrete or mortar
specimen to axial loading expressed as pounds per square inch {psi) of
cross-sectional area. The maximum compressive stress which material,
portland cement, concrete, or grout is capable of sustaining.
Concrete A composite material which consists essentially of a
binding medium, within which are embedded particles or fragments of a
relative inert filler in portland cement concrete, the binder is a
mixture of portland cement, possibly additional cementitious materials
such as fly ash and water; the filler may be any of a wide variety of
natural or artificial, fine and coarse aggregates; and in some
instances, an admixture.
Condensation When a moisture laden gas comes in contact with a
cooler surface a change of state from gaseous to liquid occurs.
Consistency The degree of plasticity of fresh concrete or mortar The
normal measure of consistency is slump for concrete and flow for mortar.
Consolidation - Compaction usually accomplished by vibration of
newly placed concrete to minimum practical volume, to mold it within
form shapes and around embedded parts and reinforcement, and to
eliminate voids other than entrained air.
Construction Joint The contact between the placed concrete and
concrete surfaces, against or upon which concrete is to be placed and to
which new concrete is to adhere, that has become so rigid that the new
concrete cannot be incorporated integrally by vibration with that
previously placed. Unformed construction joints are horizontally placed
or nearly so.
Cure Method of maintaining sufficient internal humidity and proper
temperature for freshly placed concrete to assure proper hydration of
the cement, and proper hardening of the concrete. |
