Product Brochure

6
PRECAST CONCRETE
Precast concrete uses molds to form cement into
a specic shape. The molds can oen be reused
to allow formaons of the same exact shape to be
made over and over again. The business of precast
concrete manufacturing is one where you oen
have to hurry up and wait. Once you pour a precast
form, you then have to wait for the me-consuming
process of allowing the form to fully cure.
The precast concrete industry, much of which
focuses on custom projects and applicaons,
adheres to a strict standard of quality controls for
producon purposes. These quality controls include
paying close aenon to the raw materials such
as sand, cement, aggregates, chemicals (if needed)
and water used in the process and development
of the proper mix design. All of the quality control
measures taken and all the aenon paid to the
details and standards set forth by Naonal Precast
Concrete Associaon (NPCA) would be rendered
somewhat meaningless if proper curing procedures
and techniques were not followed closely.
CURING CHALLENGES
There is a growing paern and demand for higher
compressive strengths and being able to realize
those PSI rangs in a shorter curing cycle me.
While these issues can challenge producon at
any me it is parcularly challenging during pe-
riods of the year when cold weather becomes a
factor. Common problems encountered during the
cold-climate mes of the year can include but are
not necessarily limited to:
• Potenal freezing in the early stages of place-
ment
• Inability to achieve required compressive
strengths within a specied period of me
• Improper curing procedures
• Frequent and /or rapid temperature change
Moisture Retenon
One of the more crical elements in the curing
process is moisture retenon. The evaporaon rate
of this moisture needs to be controlled as much
as possible and cold weather is an unacceptable
excuse for delaying producon. Cycle me can
obviously take longer during periods of cold weath-
er and me is money. The ambient temperature can
slow both the evaporaon rate and the curing me.
Ulizing heat in conjuncon with moisture curing is
a proven to be a soluon to this problem.
Heat During Curing
Two of the most common and convenonal means
of providing heat in a precast operaon during
inial cure are steam and hot air. While eecve
during the “inial” curing stage, neither method is
recommended once the concrete slab has aained
its “inial” set.
The use of an electrically powered heang soluon
can provide several benets:
• Freeze protecon
• Sustainability of acceptable temperatures to
enhance cure
• Accelerate the achievement of specied com-
pressive strength levels while prevenng rapid
temperature uctuaons during the curing
cycle