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Just
came across an article written by Don Thrailkill, an ACI
member.
It is worth reading.
Solvent VOC bond breakers will soon become a thing of
the past. Water
based bond breakers will be adopted because they are
environmentally and work safe friendly.
It is recommended you read and
absorb this article. Super
Tilt W/B is a curing compound as well as bond breaker.
It can be painted as soon as the moisture has left
the slab. There
is no oxidization residue.
In hot weather always water fog spray
the slab to cook it before applying the bond breaker.
- Super
Tilt does withstand rain showers.
- It
does not oxidize.
- You
can paint the panels after the moisture has come out of
the panel.
- When
applied to manufacturers instructions “it jumps off
the slab” contractors/users words, not ours.
- Uses
only half the quantity required by solvent-based bond
breaker – so is a lot cheaper.
things to think about
to prevent bondbreaker
problems
Selecting a Bondbreaker
by Don Thrailkill*
There
are many factors that must be considered when
producing tilt-up panels. It is absolutely necessary
to provide a suitable casting slab on which the
panels are to be cast - a sound, dense, smooth
concrete surface; strict attention must be given to
mix design (use of fly ash, how much water, if any,
to add on site); the use of moisture barriers; the
temperature at the time of placing; the vibration of
the concrete; and proper finishing and curing
techniques.
One
of the lease considered items, however, can also be
one of the most important and is crucial to a
successful tilt-up project. That is the type, use
and application of the curing compound and
bondbreaker. If there is any doubt about the quality
of the surface that the panels are to be cast
against and the amount of bondbreaker required under
the particular conditions, the manufacturer of the
bondbreaker should be consulted. It is too late to
ask for assistance after the concrete is placed.
As
an example of how various factors can affect the
casting slab surface, consider the following
circumstances: the temperature is 9 to 100 F at the
time of placing, fly ash is added to the concrete at
the rate of 20 percent, water is
added
onsite for workability, and the addition of a curing
coat is delayed by 30 min or more. Under these
conditions, it is highly unlikely that a smooth,
sound, dense surface will be obtained on the casting
slab. Much more bondbreaker than usual would be
required, and even then, there could be problems.
When large quantities of fly ash or other pozzolans
are used without adequate mixing, uneven
distribution of the pozzolan within the concrete mix
could occur. This could result in soft, weak areas
in the slab that would absorb the bondbreaker. When
the panels are then lifted, these weak areas could
be pulled out of the slab.
Other
factors that should be considered when selecting a
curing compound and bondbreaker are:
1)
One product that performs both as a curing
compound and bondbreaker should be selected; this
insures compatibility between these materials and
eliminates the possibility of the wrong product
being used for either one of the functions.
2) Weather conditions at the job site: rain
and heat adversely affect some bondbreakers’
performance; will the bondbreaker withstand rain
showers?
3)
Durability of the bondbreaker if there are
delays in casting the panels: some products oxidize
and must be replaced after several days.
4)
Will the panels be painted? Many bondbreakers
leave a residue that must oxidize or be removed
before paints can be applied: bond- breakers are
available that leave a paintable surface without any
preparation or waiting period.
5)
Are panels to be left exposed? Some
bondbreakers leave stains.
6)
Is a floor treatment to be applied to the
casting slab? Some curing compounds and bondbreakers
leave a surface residue that inter- feres with the
bonding of flooring materials.
7)
Is technical field assistance availablefrom the manu
-facturer of the curing com- pound and bondbreaker?
This can be important.
Many
factors must be con- sidered in selecting a curing
compound and bondbreaker for tilt-up construction.
If all the considerations listed in this article are
accounted for, a successful job is likely. Remember,
it does not have to be the bondbreaker’s fault.
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