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DUSTING-
The presence of a powdery material at the surface
of a hardened concrete slab.
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Premature
Finishing- This brings excess water, cement,
and fines to the surface, which weakens the
paste. |
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Carbonation-
Open salamanders, heaters, or engines give
off carbon dioxide, inhibiting the normal
hydration process. |
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Condensation-
Can occur when the temperature of concrete
on an inside floor made with cool materials
rises slower than surrounding, more humid
air- common in spring and fall. |
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Inadequate
Curing- "Dryout" will occur where
there is not sufficient moisture to continue
the hydration process of the Portland cement
paste, producing a soft, weakened material. |
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Do
not begin finishing operation until all free
water has evaporated or been removed from
the surface, so that the concrete will support
the weight of finisher. |
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Vent
exhaust and/or fumes to the outside, provide
adequate ventilation. |
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When
high humidity is anticipated, use heated concrete.
Open windows for ventilation and use blower-type
heaters or fans to increase air circulation.
Delay finishing operations until free water
on the surface has been removed, but do not
allow surface to dry out. |
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PLAN
AHEAD- Provisions should be made by the contractor
prior to the placing of concrete to assure
adequate time for proper placing, finishing,
and curing based on the existing conditions
at the job site. |
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