What
are some of the environmental benefits of concrete?
Aside
from concrete being long lasting and durable, there are
many other benefits to concrete including ease of design
and construction; appearance versatility; economic benefits
such as reduced energy costs; and environmental benefits.
To learn more about these benefits, click
here to review more information.
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What
is the initial cost difference between concrete versus asphalt?
The
initial cost difference between constructing with concrete
versus asphalt depends on a variety of design elements
such as, but not limited to pavement thickness, soil conditions,
design criteria and/or equipment use for placement. For
projects less than 50,000 square feet, the initial cost
may be less or equal to that of asphalt, provided that
both systems have the same structural number (SN). The
savings, when using concrete, are: the cost of mobilization
of heavy equipment necessary to achieve high-density requirements
for the subgrade and the limerock base; the cost of base
materials and labor for proper placement; and the cost
of cut/fill to compensate for the base layer. Download
the Life-Cycle Cost Analysis Program to evaluate your
project costs.
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Can
you control cracking problem in concrete paving?
Certainly!
Cracks typically occur during the first 24 to 48 hours
when stresses created by the natural drying shrinkage
exceed the tensile strength of concrete. One can control
a cracking problem in concrete paving by having a uniform
subgrade support, performing proper curing immediately
after final finish and placing proper control/contraction
joint spacing within 12 hours after placement. Click
here to sign-up for an in-house workshop for you and
your entire design staff.
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Why
should I use a certified finisher for my job? And how can
I locate one?
When
it comes to concrete pavement, quality is the main goal.
If the "bottom line" is in question, then you
do not need to worry. Certified finishers do not come
at a premium cost, however, they will offer quality construction
knowledge, skills and equipment.
- Click
here to locate a certified finisher in your area
- Click
here if you are a finisher and would like to get
certified
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What
is an isolation joint?
Also
known as expansion joints, isolation joints separate slabs
from fixed objects like walls and columns so that slabs
can move independently of other parts of the structure.
Isolation joints permit vertical and horizontal movement
between the slab and any fixed objects that the slab abuts.
The isolation joint material must be compressible and
thick enough to allow such movement. To learn more, click
here to setup an in-house workshop for you and your
design staff.
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What
is the proper spacing for control/contraction joints?
Having
proper joint spacing is vital to long-term performance
of your concrete pavement. The rule-of-thumb for maximum
joint spacing is 30 times the pavement thickness converts
in unit of feet (i.e. Thickness = 4.0 inches; Joint Spacing
= 120 inches or 10 feet). The maximum spacing for pavement
thickness exceeding 6 inches is 15 feet. Keep panels as
square as possible; the maximum length to width ratio
is 1.25:1. The best practice for designers is to layout
predetermined spacing on the plan prior to construction.
To learn more, click here
to setup an in-house workshop for you and your design
staff.
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When
is the proper time to saw-cut control/contraction joints?
Do
not wait until the next day! Contraction joints can be
sawed as early as 3 hours after placement, but do not
exceed the 12th hour. To determine the proper time of
saw cutting, operation should not cause surface deformation
or raveling along the edges of the joint. An early-entry,
dry-saw machine is recommended.
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Why
and when should I cure my concrete pavement?
Concrete
does not gain proper strength by drying out. The hardening
of concrete depends on a chemical reaction or the hydration
of cement. The hydration process depends on temperature,
time and moisture. The amount of shrinkage and curling
of slabs can be reduced by performing proper curing. Curing
should start as soon as placing and finishing is completed-the
surface will not be damaged. To learn more, click
here to setup an in-house workshop for you and your
design staff.
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Can
I eliminate welded wire mesh for my concrete parking lot?
What's the alternative?
Yes!
According to the American Concrete Institute (ACI) 330R-01
Guide for Design and Construction of Concrete Parking
Lots, "The sole function of the distributed steel
reinforcement is to hold together the fracture faces if
cracks form." Moreover, "When pavement is jointed
to form short panel lengths that will minimize intermediate
cracking, distributed steel reinforcement is not necessary.
The use of distributed steel reinforcement will not add
to the load-carrying capacity of the pavement and should
not be used in anticipation of poor construction practices."
When the purpose is to minimize plastic shrinkage and
settlement cracking, use synthetic fibers. They reduce
bleeding, increase impact and shatter resistance, as well
as abrasion resistance.
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What
is pervious concrete?
Unlike
conventional concrete, Portland cement pervious concrete
typically contains a void content of 15-25% offering vertical
drain ability versus horizontal runoffs. Pervious concrete
pavements improve filtration by allowing an enormous amount
of surface area to catch oils and chemical pollutants,
where 90% of pollutants are typically carried by the first
1-½ inches of rainfall through traditional horizontal
runoff into rivers and streams. Since pervious concrete
allows water to percolate into the ground, nearby vegetation
is watered thus reducing the need for irrigation; ground
water is recharged; and stormwater runoff quality is improved
yet reduced. To find a pervious seminar near you, click
here.
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How
can I ensure proper density around drainage structures?
One
of the common failures which can occur on a concrete parking
lot is around drainage structures. Inadequate compaction
of backfill material around these structures can result
in loss of support for the pavement. In lieu of using
compacted backfill, an option is to use a controlled density
fill material (also known as Controlled Low Strength Material/
CLSM) or flowable fill. This will prevent settlement of
the slab. To learn more, click
here to setup an in-house workshop for you and your
design staff.
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