-- Certain chemicals have been developed over
the years to alter the properties of concrete and these are
added during the mixing process. In freezing weather, a
chemical can be added to lower the freeze point of the wet
mixture. In hot weather
and long distance hauling, crushed ice is sometimes added to the
mixture to extend
time before the concrete begins to set. Fly ash costs less than
cement and can be
substituted up to about 10 percent. Concrete is sometimes
colored with dyes. Forms
are often sprayed with chemicals to prevent concrete from
bonding to them.
Chemicals are available to increase the workability of concrete
or to advance the
setting.
-- A variety of graded materials that are
components of concrete. Sand, gravel, or crushed stone are
typical aggregates. A typical mix of concrete would contain
aggregates of two are more sizes one of which is always sand
followed by one or more
sizes of rock or crushed stone.
-- Finely ground calcined rock and clay materials
that form the binder in concrete. Portland cement weighs about
97 pounds per cubic foot.
-- Plastic shapes used to support reinforcing
steel prior to placement of concrete.
-- Mixture of cement, aggregates and water that
will harden or set into a solid
stone-like material.
-- Portable or fixed machinery that
measures components of concrete and
places them in a mixer truck or is mixed on site for transport.
-- The time for fresh concrete to reach its design
strength. Typically concrete will reach 90 percent of design
strength about 30 days after placing and gradually approach 100
percent over time. A recent development is HES or High Early
Strength
concrete. Chemical additives like HES make it possible to use
certain concrete
structures after only a few hours of curing.
-- By-product of smoke stack emission control that
may be used as a substitute for a portion of the cement in a
concrete mix.
-- A mold in which concrete is placed to set. These may be made
of used wood materials, plastics, metal, etc. Some are
disposable and other reusable. Can be self-constructed,
purchased, or rented.
-- Small platform, tray or trough that has a pole handle and
that is borne on the shoulder for carrying loads as mortar or
brick.
-- A laborer employed in carrying supplies to
bricklayers, stonemasons, cement finishers, or plasterers on the
job.
-- Oven where high temperatures are used to fire bricks or other
ceramic products.
-- Special low density concrete used
where strength is not a primary requirement.
-- Generic term given to a broad class of skilled
workers who make final placement of shaped masonry products and
concrete.
-- A special type of cement used as a
component in the laying of bricks or blocks.
-- Generic name given cement for general purpose
concrete. First used by a 19th century developer of concrete.
Named for a type of stone found in the British Islands.
-- A technique used mainly in the forming
of foundation slabs where threaded steel rods are embedded in
the concrete but transverse tension is not placed on the
concrete until after the concrete is cured.
-- A technique of embedding steel in
concrete shapes so that the end result will meet certain design
specifications for strength and rigidity.
--Equipment that is often truck mounted used to
pump concrete from one place/level to another.
-- Steel rods ranging from 3/8- to 3-inches thick
placed in concrete forms to produce reinforced concrete.
-- Shapes containing steel bars or
wire to create stronger and more shock resistant material.
-- A field test given to concrete before curing that measures
the viscosity and indirectly the water content. Generally the
less viscous, the higher the cured strength for any given mix.
-- Concrete strength is usually expressed in
terms of pounds per square inch (PSI). 3,000 PSI is a typical
specification for building foundations. A sample of wet concrete
is placed in a test cylinder and after curing, the sample is
compressed to its breaking point on a machine built to show a
reading when the concrete breaks. Sometimes a sample is cut from
the cured concrete with a circular cylinder cutter. An older and
less precise measurement of strength is given in terms of
"sacks" per yard. In other words a five bag mix would contain
about 500 pounds of cement per cubic yard of concrete.
Tie Wire -- Short pieces of wire used to secure rebars in place
until the concrete has been poured and at least partially cured.
-- Concrete that is mixed while being
transported by truck to a job site.
-- Small strips of metal fastened to a building's
primary structure to hold the masonry in place.
Source:
Department of the Treasury
Internal Revenue Service Training 3147-122 (8-98)
TPDS No. 85385S |