AASHO - American
Association of State Highway Officials
Abrasion - The process of
wearing down or rubbing away by means of friction.
Adhesion - A
property of
soil which causes the particles to stick together.
Aggregate - Stone or gravel that was
crushed and screened to various sizes for use in concrete, asphalt or
road surfaces.
Amplitude - The total vertical distance the
vibrating drum or plate is displaced from a resting or neutral
position from the eccentric moment.
Articulate - To fit together
into a coherent whole; unify.
ASTM - American Society for Testing
Materials.
Attenuation - To reduce in
force, value, amount of degree.
Backfill - Materials used in refilling a
cut or other excavation, or the act of such refilling.
Ballast - Heavy material, such as water,
sand or metal which has no function in a machine except to increase
its weight.
Bank - A
mass of soil rising above an
average level. Generally, any soil which is to be dug from its
natural position.
Bank Gravel - A
natural
mixture of cobbles, gravel, sand and fines.
Bank Yards - Soil or rock
measured in its original position before digging.
Base - The course or layer of
materials in a roadway section on which the actual pavement is placed.
It may be of different types of materials ranging from selected soils
to crushed stone or gravel.
Berm - An artificial ridge of earth,
generally side-slopes of a roadbed.
Binder - Fines which fill voids or hold
gravel together when dry.
Borrow Pit - An excavation
from which fill material is taken.
BPR - U.S. Bureau of Public Roads
BUREC - U.S. Bureau of
Reclamation
Capillary - A
phenomenon of soil which
allows water to be absorbed either upward or laterally.
Cavitation - The sudden
formation and collapse of low pressure bubbles in liquids by means of
mechanical force.
Centrifugal Force -
The force generated from the
unbalanced condition of eccentric shaft rotation at a given speed.
Clay - Material composed and derived
from the decomposition of rock which consists of microscopic
particles.
Clean - Free of foreign material; in
reference to sand or gravel, lack of a binder.
Cohesion - A
property of soil which holds
the particles together by sticking. Also, the soil's ability to
resist shear is determined by its degree of cohesiveness.
Cohesive Material -
A soil having properties of
cohesion.
Compacted Yards -
Measurement of soil or rock
after it is placed and compacted in a fill.
Compressibility -
A property of soil which
permits deformation when subjected to a load.
Core - A
cylindrical piece of an
underground formation, cut and raised by a rotary drill with a bit.
The impervious center of an earth fill dam.
Crown - The elevation of a road surface
at its edges, to encourage drainage.
Datum - Any level surface taken as a
plane of reference from which to measure elevations.
Density - The ratio of weight of a
substance to its volume.
Dewatering - The act of
removing water.
Diaphragm - A
part that
divides or separates.
Displacement -
A dislocation
caused by a slipping of rock masses along a plane of fracture.
Dynamic - Relating to
energy or to objects in motion.
Embankment - A
fill with a top higher than
the adjoining natural surface.
Elasticity - A
characteristic of soil which
allows deformation during a subjected load, but returns almost to its
original configuration after removal of the force.
Fines - Clay or silt particles in soil.
Finish Grade -
The final grade required by
specifications.
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.
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.
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.
Gravel - A
cohesion less aggregate of
rock fragments with varying dimensions of 3.0 to .08 inches.
Gumbo - Material in the plastic state
identified by a soapy or waxy appearance.
Humus - Organic material formed by the
decomposition of vegetation.
Impeller - An object that
drives forward; propels.
Impervious - Resistant to movement of water.
In Situ - Natural undisturbed soil in
place.
Lift - A
layer of fill as spread on
compacted.
Liquid Limit -
The water content at which soil
passes from a plastic to a liquid state.
Loam - A
soft, easily worked soil
containing sand, silt, clay and decayed vegetation.
Optimum Moisture
Content - That
percent of moisture at which the greatest density of a soil can be
obtained through compaction.
Pass - A
working trip or passage of an
excavating, grading or compaction machine from point A to point B.
(One direction only.)
Permeability -
A characteristic of soil which
allows water to flow through it because of gravity.
Plastic - The ability of a soil to be
rolled into a fine thread at a certain moisture content.
Plastic Limit -
The lowest moisture content at
which a soil can be rolled into a 1/8" diameter thread without
breaking.
Proctor - A
method developed by R.R.
Proctor for determining the density/moisture relationship in soils.
It is almost universally used to determine the maximum density of any
soil so that specifications may be properly prepared for field
construction requirements.
Proctor, Modified -
A moisture density test of more
rigid specifications than Proctor. The basic difference is the
use of heavier weight dropped from a greater distance in laboratory
tests.
Quicksand - Fine sand or silt that is
prevented from settling firmly together by upward movement of
underground water.
Sand - A
cohesiveness aggregate of
round and angular fragments of rock with a particle size between 2.0
and .05 mm.
Shearing Resistance -
A soil's ability to resist
sliding against neighboring soil grains when force is applied.
Internal friction and cohesion determine shear resistance.
Shrinkage - Soil volume which is reduced
when subjected to moisture; usually occurs in fine grain soils.
Silt - Soil material composed of
particles between .005 and .05 mm in diameter.
Soil - The
loose surface material of the earth's crust.
Stabilize - To make soil form and prevent
it from moving.
Static - Having no
motion; being at rest.
Static Force -
Is simply the deadweight of the machine, applying
downward force on the soil surface, compressing the soil particles.
Sub-base - The layer of
material placed to furnish strength to the base of a road.
Sub grade - The surface produced by grading
native earth, or cheap imported materials which serve as a base for
more expensive paving.
Vacuum - Containing air
or other gas at a reduced pressure.
Vibratory Force
- Uses a mechanism, usually engine-driven, to
create a downward force in addition to the machine's static weight.
The vibrating mechanism is usually a rotating eccentric weight or
piston/spring combination (in rammers).
Viscosity - The amount of
resistance to flow.
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