Concrete and paving glossary - D
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Dampproofing
A process used on concrete, masonry or stone surfaces to repel water,
the main purpose of which is to prevent the coated surface from absorbing
rain water while still permitting moisture vapor to escape from the
structure. (Moisture vapor readily penetrates coatings of this type.)
"Dampproofing" generally applies to surfaces above grade; "waterproofing"
generally applies to surfaces below grade.
Darby (derby, derby float, derby slicker)
A stiff straightedge of wood or metal used to level the surface of
wet concrete. A portable machine with large paddles like fan blades
used to float and finish concrete floors and slabs. A large power-driven
machine mounted on wheels that ride on steel pavement forms and is used
to finish concrete pavements. See screed
and float.
Derated concrete
Concrete that has had a gas-forming chemical added to it so that when
it sets it contains many air holes and is lightweight.
Dispersants
A material capable of holding finely ground particles in suspension.
Used as a slurry thinner or grinding compound. See slurry.
Division plate
A concrete forming accessory used to create a break in a concrete sidewalk
or curb and gutter. This engineered break minimizes the chances of the
poured concrete cracking due to the surrounding ground shifting as a
result of variety of factors including freezing, thawing, or heat expansion.
Division plate (full)
Full plates are used as bulkheads in the curb and gutter system and
also are used to hold expansion material during concrete placement.
Division plate (punched for dowel)
Division plates punched for dowel are full division plates with slots
punched on the bottom to accommodate the use of dowels or rebar. The
punched slots hold the dowels or rebar in place during placement and
prevents the material from floating in the placement. See dowel
and rebar.
Division plate (skeleton)
Skeleton division plates are used to support the curbface form and
add support for the curb and gutter system. See curb
face form.
Division plate (slotted for rebar)
Also known as an S/B division plate. Division plates with slots for
rebar provide the contractor
with the ability to ensure the rebar will stay exactly where it is positioned
into a curb and gutter placement, eliminating problems with the final
rebar positioning.
DOT
The acronym for the Department of Transportation.
Dowel
A cylindrical piece of stock inserted into holes in adjacent pieces
of material to align and/or attach the two pieces. See rebar
and reinforced
concrete.
Dowel-bar reinforcement
Short sections of reinforcing steel that extend from one concrete placement
into the next. They are used to increase strength in the joint. See
dowel, rebar,
and reinforced
concrete.
Dowel lubricant
A lubricant applied to dowels placed in adjoining concrete slabs to
allow longitudinal movement in expansion joints. See dowel,
expansion joint,
and rebar.
Dowel screw
A threaded dowel. See dowel.
Dry concrete
Concrete that has a low water content, making it relatively stiff.
The effects are a lower water-cement ratio, less pressure on forms,
lower heat of hydration, and a consistency that allows for placement
on a sloping surface. See heat
of hydration.
Dry pack
A low-slump grout tamped into the space in a connection between pre-cast
concrete members. See slump
and pre-cast concrete.
Dry shake (dry topping)
A concrete surface treatment, such as color, hardening, or antiskid,
which is applied to a concrete slab by shaking on a dry, granular material
before the concrete has set and then troweling it in. See shake-on
hardener and troweling.
Drying shrinkage
Contraction caused by the loss of moisture, particularly in concrete,
mortar, and plaster. See shrinkage.
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