Civil Engineering Reference
In-Depth Information
Table 4.1 (Continued)
Admixtures, their characteristics, and usage
Admixture type
Effects and benefits
Materials
Extended set control
(hydration control)
(ASTM C494/C494M,
Type B or D)
Used to stop or severely
retard the cement
hydration process. Often
used in wash water and in
returned concrete for reuse
and can provide medium-
to-long-term set retardation
for long hauls. Retain slump
life in a more consistent
manner than normal
retarding admixtures.
Carboxylic acids.
Phosphorus-containing
organic acid salts.
Shrinkage reducing
Reduce drying shrinkage.
Reductions of 30% to 50%
can be achieved.
Polyoxyalkylene alkyl ether.
Propylene glycol.
Corrosion inhibiting
(ASTM C1582/C1582M)
Significantly reduce the rate
of steel corrosion and
extend the time for onset
of corrosion.
Amine carboxylates
aminoester organic
emulsion, calcium nitrite,
organic alkyidicarboxylic.
Chromates, phosphates,
hypohosphites, alkalies, and
fluorides.
Lithium admixtures to
reduce deleterious
expansions from
alkali-silica reaction
Minimise deleterious
expansion from alkali-silica
reaction.
Lithium nitrate, lithium
carbonate, lithium
hydroxide, and lithium
nitrite.
Permeability-reducing
admixture:
nonhydrostatic
conditions (PRAN)
Water-repellent surface,
reduced water absorption.
Long-chain fatty acid
derivatives (stearic, oleic,
caprylic), soaps and oils
(tallows, soya based),
petroleum derivatives
(mineral oil, paraffin,
bitumen emulsions), and
fine particle fillers
(silicates, bentonite, talc).
Permeability-reducing
admixture: hydrostatic
conditions (PRAH)
Reduces permeability,
increased resistance to
water penetration under
pressure.
Crystalline hydrophilic
polymers (latex, water-
soluble, or liquid polymer).
Bonding
Increase bond strength.
Polyvinyl chloride, polyvinyl
acetate, acrylics, and
butadiene-styrene
copolymers.
Colouring
Coloured concrete
Carbon black, iron oxide,
phthalocyanine, raw burnt
umber, chromium oxide,
and titanium dioxide.
(
Continued
)
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