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freshly placed concrete shall hc covrrcd and protected against surface wash.
shall bc taken to prevent the formation of lean scams
or sand streaks.
Mortar coats for bonding construction
joints as specificd under 4.9.1, 184.108.40.206 and 4.10.5 shall not be placed or left exposed if
the rain is tending
to increase the water-cement
ratio of the mortar.
Under no conditions shall concrete bc placed in a pool or a sheet of water.
The top of all badly washed or streaked surfaces shall be removed and
wasted bpfore depositing the next course.
4.14 Curing and Protection 4.14.1 All concrete
finished surfaces of concrete shall be
from the sun for at least 72 hours
general, be kept continuousiy
joints shall protected
protected against heating and drying
Concrete shall, in
moist for not less than
be cured in the same way as other
25 1s : 454 - 1957
concrete and shall also, if practicable, be kept moist for at least 72 hours
prior to the placing of additional concrete upon the joint.
and approximately horizontal surfaces shall be cured by sprinkling or by
covering with damp sand, or by the use of wet sacks which satisfactorily retain the required amount of water for curing purposes. Where damp
sand or sack cover is used for curing, it shall be completely removed later.
Water curing shall be used ‘on all concrete in dams and shall be applied
by means of sprays or sprinklers to cover the entire area of the concrete.
Forms shall be kept sprinkled until removal.
Concrete shall not be disturbed by workmen walking on it or by storing materials on the surface
or otherwise for at least 10 hours after placing.
4.14.2 In special cases, such as powerhouses, the use of an approved,
properly-applied sealing compound on limited areas shall be permitted.
The curing compound shall be of the surface membrance type which shall
thoroughly seal the concrete surface.
Curing compound shall not be used
on joints where bonding is required.
The concrete surface shall be
thoroughly wetted before applying the compound. All surfaces covered
with curing compound shall be protected from trafhc or injury of the sealing
coat until expiration of the curing period. All methods used for curing
shall leave the concrete free from any discolouration or damage to the
4.15 Repair of Concrete -Repair
of all impcrfcctions of the concrete
surfaces necessary to p-~~**pp surfaces that conform to the requirements
shalI be completed as soon = practicable’ after removal of forms and whereever possible within 24 hours after tire removal of forms. Fins shall be
neatly removed from surfaces for which finishes F2 and F3 ( see 4.16.2 )
Concrete that is damaged from any cause, and concrete
that is honey-combed, fractured, or otherwise defective, and concrete,
which because of cxccssive surface clepressions, has to be excavated and
built up to bring the surf;lce to...
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- Fall '13