Sacking Removing or alleviating defects on a concrete surface by
applying a mixture of sand and cement to the moistened surface and
rubbing with a coarse material such as burlap.
Sand (ASTM C125) That portion of an aggregate passing the No. 4
(4.76 mm) sieve and predominantly retained on the No. 200 (74 micron)
Sand Blast A system of abrading a surface such as concrete by a
stream of sand, or other abrasive, ejected from a nozzle at high speed
by water and/or compressed air.
Saponification The deposit of a gray scum or gray dust on the inside
surface of a subgrade wall or floor; as the result of moisture moving
through the concrete and washing certain chemicals from the concrete
Scaling The breaking away of a hardened concrete surface, usually to
a depth off/IS' to 3/16'.
placed grade strips or side forms which are set as guides for a
straight edge to bring the surface of concrete to the required
strike off concrete above the desired level.
Screen (or Sieve) A metallic sheet or plate, woven wire cloth, or
similar device, with regularly spaced openings of uniform size, mounted
in a suitable frame or holder for use in separating material according
Segregation The tendency for the coarse particles to separate from
the finer particles in handling. In concrete, the coarse aggregate and
drier material remains behind and the mortar and wetter material flows
ahead. This also occurs in a vertical direction when wet concrete is
over vibrated or dropped vertically into the forms, the mortar and
wetter material rising to the top. In aggregate, the coarse particles
roll-to the outside edges of the stockpile.
Set A term used to describe the stiffening of cement paste; a
condition reached by a concrete, cement paste, or mortar when plasticity
is lost to an arbitrary degree, usually measured in terms of resistance
to penetration or deformation. (Initial set refers to first stiffening.
Final set refers to attainment of significant rigidity.)
Setting Time The time required for a specimen of cement paste,
mortar or concrete, prepared and tested under standardized conditions to
attain a specified degree of rigidity with particular reference to
initial and final setting time.
Shotcrete Mortar or concrete conveyed through a hose and projected
pneumatically at high velocity onto a surface; dry-mix shotcrete (gunite),
and wet-mix shotcrete.
Sieve See "Screen"
Sieve Analysis Determination of the proportions of particles of The
granular material lying within certain size ranges on sieves of
different size openings.
Slip Form A form which is raised or pulled as concrete is placed;
may move vertically to form wails, stacks, bins or silos, usually of
uniform cross section from bottom to top; or a generally horizontal
direction to lay concrete evenly for highways, on slopes and inverts of
canals, tunnels, and siphons.
Slump A measure of the consistency of plastic concrete relative to
the amount it falls when a slump cone filled with concrete is lifted
vertically. The slump cone is then placed beside the specimen of
concrete and the number of inches from the top of the cone to the top of
the of specimen of concrete is the slump. (see ASTM C143).
Slump Cone A metal mold in the form of a truncated cone with a top
diameter of 4”, a bottom diameter of 8”, and a height of 12”, used to
fabricate the specimen for a slump test.
Slurry A mixture of water and such finely divided materials, such as
portland cement, slag, or soil in suspension.
Spall A fragment, usually of flaky shape, detached from a larger
mass by pressure, expansion from within the larger mass, a blow, or by
the action of weather.
Specific Gravity The ratio of the weight of a material at a stated
temperature to the weight of the same volume of gas-free distilled water
at a stated temperature.
Stucco A portland cement mortar material that can be applied to the
surface of any building or structure to form a hard and durable covering
for the exterior wails or other exterior surfaces.
Sulfate Attack Deleterious chemical and/or physical re-action
between sulfates in ground water or soil and certain constituents in
cement, which result in expansion and disruption of the concrete.
Sulfate Resistance Ability of cement paste, aggregate, or mixtures thereof to withstand sulfate attack.
Surface Moisture Free moisture retained on the surfaces of aggregate
particles which becomes part of the mixing water in the concrete mix;
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