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Will the color of
the concrete change as it cures?
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What is a slump?
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What is a tamp used
for?
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How long does it
take for concrete to dry enough to walk on?
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How long does it
take for concrete to cure enough to drive on?
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Should I put cure
or water on the concrete?
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Do I need ABC for
subgrade?
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What is a
control/construction joint
and where
are they needed?
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What is an
expansion board and where are they needed?
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What are the Terms and Conditions for
Mobile Mix, Inc.?
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Glossary
of Concrete Terminology
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Do-It-Yourself Guide
Will the color of the concrete change
as it cures?
Yes it will become
lighter as it cures.
What is a slump?
The slump refers to
the consistency of the concrete. (how wet or dry the mix is)
What is a tamp used for?
A tamp is used to
blend the aggregate downward into the mix and bring the “cream” to the top. The
use of a tamp will provide a more workable mix and allow for a proper finish.
How long does it take for concrete to
dry enough to walk-on?
Wind, humidity, and
sunlight are all factors in how long it takes for concrete to dry.
How long does it take for concrete to
cure enough to drive-on?
Again,
wind, humidity, and sunlight are all factors but the standard is 5-7 days.
Should I put cure or water on the
concrete?
Yes,
after the initial 12 hours applying cure of water for 5 days every morning and
night is recommended.
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Do I need ABC for
subgrade?
Only if
you are raising the elevation of the pour, ABC will need to be compacted.
What is a
control/construction joint and where
are they needed?
It is a
groove joint used to control concrete cracking. They are needed no more than 1.5
x the width.
What is an
expansion board and where are they needed?
It is
material placed in the concrete to allow for expansion and contraction of the
concrete. They are needed
if you have 2 sides that are constricted and parallel it is recommended as well
as if you have 3 sides combined.
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What are the Terms and
Conditions for Mobile Mix, Inc.?
Mobile
Mix, Inc. Terms and Conditions
- There are NO REFUNDS on concrete orders
- As a courtesy we can help re-check your measurements
- Mobile Mix, Inc. and
THE HOME DEPOT
are not responsible for any finished work done to delivered concrete.
- Offload time is 10 minutes per cubic yard. If
allotted time is expired, customer will be charged $2 per minute.
This is at the driver’s discretion.
- Wheelbarrows, and hand/concrete (tools) are not included in
concrete price. These items can be rented or purchased at your local HOME
DEPOT store.
- Customer is responsible for wheel barrowing concrete
to pour site if needed.
- Mobile Mix, Inc provides a Curbside delivery
service only. Deliveries beyond the curbside are done at the drivers
discretion.
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Accelerator
- Chemical substance added to a concrete mix that reduces the set time by
increasing the rate of hydration.
Aggregate –
Concrete is a mixture of water, Portland cement, and aggregates (sand and / or
stone). Sand is considered a fine aggregate, while any stones are coarse
aggregates.
Bull Float –
a tool comprising a large, flat, rectangular piece of wood, aluminum, or
magnesium usually 8 inches wide and 48 inches long and a handle 4 to 16 feet in
length used to smooth unformed surfaces or freshly placed concrete.
Cubic Yard –
Unit of measure for ready mix concrete. Concrete is ordered, sold, and batched
by volume.
Curing – The
maintenance of the proper moisture and temperature of concrete is its early
stages that desired properties may develop.
Portland cement
– A hydraulic cement that sets and hardens by chemical interaction with water.
Sack mix –
The amount of sacks of cement in a cubic yard of concrete. Specified when
ordering, concrete is typically referred to as a 5 sac mix. The sacks of cement
needed in a mix are usually specified in either the plans or the specifications
of a project. More sacks = more strength.
Screeding –
The operation of forming a surface by the use of a screed or strike-off and
screed guides. (typically, the forms)
Set time – A
measurement in hours and minutes of the hardening of concrete to resist a
measure of penetration.
Slump – A
measure of consistency of freshly mixed concrete, measured in inches. It is the
distance that freshly mixed concrete subsides when a conical mold (slump cone)
is lifted from the test specimen. Increasing the slump is typically done by
increasing the batch water. This method also will begin to erode the strength
of the concrete is the slump is raised higher that its designed level.
Sub grade –
The prepared and compacted soil made to support a structure or pavement system.
Volumetric mixer
– A concrete mixer that measures and produces plastic ready mix concrete by
volume rather than weight. Volumetric mixers meter their concrete output as
they produce the concrete, also known as continuous batching.
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Step 1: Site Preparation & Planning
- Sub grade must be compacted and free of standing water
- Forms must be secure and capable of withstanding load
pressure of fresh concrete
- Arrange enough help to place and finish concrete.
Start with a minimum of 2 people for a 1 cubic yard pour. Add one person
for each additional cubic yard of concrete. If you are using wheelbarrows
to move the concrete form the truck to the forms, add an additional person.
- Assign specific responsibilities to helpers before
concrete arrives
- Provide acceptable access for delivery
- pathway must be of stable soil (able to support
85,000 pounds)
- pathway must be at least 10 feet wide and 14 feet
high
- avoid bringing trucks over curbs, sidewalks, and
driveways
- The discharge chutes can reach approx. 12 feet
- Determine what type of control joints will be used to
control cracking; hand tooled or saw cut. TIPS:
- Concrete used for residential applications should be
at least 4 inches thick
- Placement of control joints should be determined in
the planning step
- Control joints should be placed no more than 10
feet apart
- Sections should be square or nearly square
- The joint depth should be at least ¼ the thickness
of the concrete
- Avoid creating triangles or odd shaped panels when
placing joints
Step 2: Placement
- Concrete must be discharged as close to final position
as possible (eliminate “dragging” concrete long distances)
- Concrete must be discharged in a timely manner upon
arriving to the job site. If you are using wheelbarrows to move the
concrete from the truck to the forms, make sure you have enough help to
finish the project in a timely manner.
- During the placement process, follow these easy steps:
- Strike off or “screed” the concrete to the proper
elevation or form height with a wood or magnesium straight edge
- Immediately after striking off and before bleed
water appears, the concrete must be bull floated and the edges formed
with an edger
- After bull floating, no finishing practices must
take place until bleed water has completely evaporated.
- Concrete will be glossy when bleed water is present
and will dull when it evaporates.
Step 3: Finishing
Finishing is the process of
texturing the concrete. If you are using hand-tooled control joints, these must
be completed prior to final texturing. The following textures may be applied:
- A broom or brush finish is recommended for exterior
applications that require maximum skid resistance such as; sidewalks and
driveways. To achieve a broom finish; simply push or pull the concrete
broom across the concrete when it reaches the desired consistency; timing is
a judgment call based on desired depth of broom texture.
- A porous trowel finish is recommended for exterior
applications that require minimal skid resistance such as; patios and
porches. To achieve a porous trowel finish; trowel the concrete when it
reaches a consistency that supports our weight but leaves footprints
approximately ¼ inch deep.
- A hard trowel finish is recommended for interior
applications that require a non-porous surface such as shop floors and
garage floors. To achieve a hard trowel finish the concrete must be
finished with a power trowel.
- For decorative or architectural finishes we recommend
that you hire a qualified licensed contractor that specializes in decorative
concrete.
Step 4: Curing
Curing is the most important step in concrete placement,
yet is typically the most neglected. To ensure that concrete reaches its
maximum designed strength and durability, it must be properly cured. This
process must begin as soon as the concrete will accept the process without
damage to the surface. There are two methods for curing concrete:
- Wet Curing is the process of keeping the concrete
surface saturated. A garden sprinkler is typically used for the type of
curing.
Curing Compound is
a chemical that seals in the moisture. They are typically applied with a
sprayer but can also be rolled on with a paint roller.
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