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 Keene's
Cement A finely ground high density plaster composed of anhydrous, (calcined
or "dead burned") gypsum, the set of which is accelerated by the
addition of other materials.
Kelly Ball A device for determining the consistency of fresh
concrete. It is sometimes used as an alternative to the slump test.
Laitance A residue of weak and non-durable material consisting of
cement, aggregate, fines, or impurities brought to the surface of
overwet concrete by the bleeding water
Lift Layer of concrete.
Liquefaction The change of state to a liquid. Term used instead of
condensation in reference to substances, which are usually gaseous.
Magnetite An aggregate used in heavy weight concrete, consisting
primarily of ferrous metaferrite (Fe304). A black magnetic iron ore with
a specific gravity of approximately 5.2 and a Mohs hardness of about 6.
Marl A calcareous clay, containing approximately 30 to 65 percent
calcium carbonate (05003), found normally in extinct fresh wafer basins,
swamps, or bottoms of shallow lakes.
Masonry Cement Hydraulic cement manufactured for use in mortars for
masonry construction. Normally a blend of two or more of the following
materials: portland cement, natural cement, portland-pozzolan cement,
hydraulic lime, slag cement, hydrated lime, pulverized limestone, talc,
chalk, pozzolan, clay or gypsum; also may include air en-training
additions.
Mass Concrete Any large volume of concrete cast in place intended to
resist applied loads by virtue of mass. Generally a monolithic
structure incorporating a low cement factor with a high proportion of
large coarse aggregate.
Mass Curing Adiabatic curing, using sealed containers.
Maximum Size Aggregate Aggregate whose largest particle size is
present in sufficient quantity to affect the physical properties of
concrete; generally designated by the sieve size on which the maximum
amount permitted to be retained is 5 or 10 percent by weight.
Mixer Equipment used for mixing or blending the materials used in
the manufacture of concrete, grout or mortar.
Mixing Speed Rate of
mixer drum rotation or that of the paddles in a pan, open-top, or trough
type mixer, when mixing a batch; expressed in revolutions per minute
(rpm) or in peripheral] feet per minute of A point on the circumference
at maximum diameter.
Mixing Time For stationary mixers, mixing time is calculated in
minutes from the completion of charging the mixer until the beginning of
discharge; for truck mixer, time is calculated in total minutes at a
specified mixing speed. the period during which materials used in a
batch of concrete are combined by the mixer
Modulus of Elasticity A measure of the resistance of material to
deformation. the ratio of normal stress corresponding strain for tensile
or compressive stresses below the proportional limit of the material;
elastic modulus is denoted by the symbol "2".
Moist Room A room used for storing and curing cementitious test
specimens. The atmosphere of this room is maintained at a temperature of
73.4 3.0'F or 23.0*1.7'0 and relative humidity of at least 98 percent.
These facilities must be adequate to continually maintain free moisture
on the exteriors of test specimens.
Monolithic A plain or reinforced mass of concrete cast as a single,
one piece, integral structure.
Mortar A mixture of cement, sand and water. When used in masonry
construction, the mixture may contain masonry cement, or standard
portland cement with lime or other ad-mixtures which may produce greater
degrees of plasticity and/or durability. |
