Concrete Curring Flashcards
Concrete temperatures below ____ degrees F make it hard to acheive early strength
60 degrees
Methods for maintaining the needed moisture content for curring fall into 2 categories 1. applying water continously 2. preventing excessive moisture loss. what is not true when considering these methods
insert curring compound into the concrete mix
when curring concrete, what is likely to be considered false
membrane - forming curring compounds provide a more effective system of curring than that of a curing paper or polyethelyne sheets
what is true when using water curing durring colder weatehr 28 Degrees to 40 degrees
water cured concrete is likely to be nearly satuated when protection is removed
what is false about curing concrete durring hot weather
immediate continous curing durring hot weather will not help to prevent craze cracking
according to ASTM C94 specification for ready mix concrete what is the timeframe when concered to the discharge rule
90 minutes
On ready mix concrete, the mixing drum must rotate at least ____ times after the water has been added at the job site
30
on vertical surfaces, leaving forms in place is an acceptable curing method.
True
Concrete is kept moist to enhance
curing
concrete should be cured for
3 days
which of the following curing procedures is most widely used today
water sprikling
Little gain in strength of concrete can be expected when
it is frozen
proper curring will help produce concrete that is
water tight
a material that may be used for curing is
waterproof paper or plastic
the upper temperature at which fresh concrete should be poured is
90 degrees F
Concrete may be plastic for ____ in hot weather
1 hr
when finishing a concrete slab, the last operation performed is
curing
when a slab is allowed to dry to rapidly it may cause the surface to
shrink
he biggest problem with concrete in hot weather is:
acceleration of hardening
extra care must be taken to avoid ____ in hot weather when pouring concrete
cold joints
which of the following is easiest to cool when pouring concrete
water
the best way to cool concrete on a hot day is to use
crushed ice
it is always best to use air- entrained concrete and ____ in cold weather concreting
calcium chloride admixture
the best method of curing is
total immersion of concrete under water
in the construction of slabs, the last step is:
curing
forms should be left in place as long as feasible to
enable better curing
