Mixture proportions depend on the specific application
and the type of polymer used in the PCC. Polymer levels of
10 to 20% polymer solids by mass of cement are required for
most desired applications. Typical w/c for workable PCC
mixtures used for repair range from 0.30 to 0.40 for mixtures
containing latexes, and 0.25 to 0.35 for mixtures containing
epoxies (ACI 548.1R).
a) Advantages—PCC overlays have exhibited excellent
long-term performance. Properly installed overlays are
highly resistant to freezing-and-thawing damage, and they
exhibit minimal bond failure after many years of service.
LMC overlays installed on severely deteriorated bridge
decks, after proper surface preparation, continue to perform
many years after installation. Reports of satisfactory longterm
performance on structures of variable initial condition
and harsh in-service exposure are common (Virginia 2001).
Mixing of PCC should be done in a concrete mobile mixer.
Handling, placing, and finishing of PCC is limited to less
than 30 min. To achieve proper curing, PCC requires one day
to two days of moist curing followed by air drying. The PCC
is placed in service when it has developed sufficient strength,
which is dependent upon the hydration of the cement.
An advantage of PCC is its good workability and ease of
application when compared to similar systems.
The bonding characteristics of PCC are excellent (Kuhlmann
1990), and PMC usually exhibits low permeability
(Kuhlmann 1984).
Styrene-butadine PCC has excellent durability for exterior
exposures or environments where moisture is present.
Surface discoloration occurs when the concrete is exposed to
UV light. Where such discoloration is not acceptable, acrylic
polymers should be used.
b) Limitations—PCC should be placed and cured at 7 to 30 °C
(45 to 85 °F) with special precautions taken when either
extreme is reached (ACI 548.1R and ACI 306.1).
Mobile, continuous mixers, fitted with an additional
storage tank for the latex should be used for large applications
of PMC. When small batches are mixed in drum or
mortar mixers, the mixing time should be limited to 3 min.
Longer mixing times result in an increase in the total air
content with subsequent reductions in compressive strength.
PMC has a tendency for plastic shrinkage cracking during
field placement. Special precautions are necessary when the
evaporation rate exceeds 0.5 kg/m2/h (0.1 lb/ft2/h) (ACI
308R and ACI 548.4).
The modulus of elasticity is generally lower compared to
conventional concrete; therefore, its use in vertical or axially
loaded members should be carefully evaluated (Kuhlmann
1990).
Polyvinyl acetate should not be used in applications that
may be exposed to moisture.
Epoxy emulsions are more expensive than most latexes,
and some are susceptible to color change and deterioration
from exposure to sunlight.
c) Applications—PCC applications include overlays of
bridge decks, parking structures and floors, and patching of
any concrete surfaces. Styrene butadiene latex is commonly
used for repair of bridges, parking decks, and floors. Acrylic
Mixture proportions depend on the specific applicationand the type of polymer used in the PCC. Polymer levels of10 to 20% polymer solids by mass of cement are required formost desired applications. Typical w/c for workable PCCmixtures used for repair range from 0.30 to 0.40 for mixturescontaining latexes, and 0.25 to 0.35 for mixtures containingepoxies (ACI 548.1R).a) Advantages—PCC overlays have exhibited excellentlong-term performance. Properly installed overlays arehighly resistant to freezing-and-thawing damage, and theyexhibit minimal bond failure after many years of service.LMC overlays installed on severely deteriorated bridgedecks, after proper surface preparation, continue to performmany years after installation. Reports of satisfactory longtermperformance on structures of variable initial conditionand harsh in-service exposure are common (Virginia 2001).Mixing of PCC should be done in a concrete mobile mixer.Handling, placing, and finishing of PCC is limited to lessthan 30 min. To achieve proper curing, PCC requires one dayto two days of moist curing followed by air drying. The PCCis placed in service when it has developed sufficient strength,which is dependent upon the hydration of the cement.An advantage of PCC is its good workability and ease ofapplication when compared to similar systems.The bonding characteristics of PCC are excellent (Kuhlmann1990), and PMC usually exhibits low permeability(Kuhlmann 1984).Styrene-butadine PCC has excellent durability for exteriorexposures or environments where moisture is present.Surface discoloration occurs when the concrete is exposed toUV light. Where such discoloration is not acceptable, acrylicpolymers should be used.b) Limitations—PCC should be placed and cured at 7 to 30 °C(45 to 85 °F) with special precautions taken when eitherextreme is reached (ACI 548.1R and ACI 306.1).Mobile, continuous mixers, fitted with an additionalstorage tank for the latex should be used for large applicationsof PMC. When small batches are mixed in drum ormortar mixers, the mixing time should be limited to 3 min.Longer mixing times result in an increase in the total aircontent with subsequent reductions in compressive strength.PMC has a tendency for plastic shrinkage cracking duringfield placement. Special precautions are necessary when theevaporation rate exceeds 0.5 kg/m2/h (0.1 lb/ft2/h) (ACI308R and ACI 548.4).The modulus of elasticity is generally lower compared toconventional concrete; therefore, its use in vertical or axiallyloaded members should be carefully evaluated (Kuhlmann1990).Polyvinyl acetate should not be used in applications thatmay be exposed to moisture.Epoxy emulsions are more expensive than most latexes,and some are susceptible to color change and deteriorationfrom exposure to sunlight.c) Applications—PCC applications include overlays ofbridge decks, parking structures and floors, and patching of
any concrete surfaces. Styrene butadiene latex is commonly
used for repair of bridges, parking decks, and floors. Acrylic
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