- Q. What is involved to replace
my driveway?
- A. The first step in replacing a concrete driveway is to break up
the old driveway and haul it away. Then, depending on the nature of
the ground under the driveway, the contractor may put down additional
gravel or fill to create a more solid base for the concrete. Without
a good base, the driveway is more likely to settle and/or crack. Additional
fill is needed in roughly half of the cases. Next, the contactor installs
temporary forms to hold the wet concrete. The forms, as the name implies,
form a template, almost like a cookie cutter. Once the forms are in
place, the concrete arrives and is poured into them. The concrete
is smoothed, and expansion joints are cut. The concrete hardens inside
the forms. Once the concrete is hard, the forms are removed.
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- Q. What causes cracks in the
driveway and how can I prevent them?
- A. The use of expansion joints will help prevent cracks. As the
name implies, expansion joints allow the concrete to expand or contract
with temperature. Without such joints, repeated expansion or contraction
often results in cracks. In temperate climates, industry experts recommend
cutting expansion joints approximately every 15 feet. In addition
to preventing cracks, expansion joints can stop cracks from propagating.
If a crack hits an expansion joint, it usually will not continue into
the section of concrete on the other side of the joint. Even with
proper expansion joints, driveways often crack. Due to the variability
of materials and terrain, many established companies would not guarantee
their driveways against aesthetic cracking.
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- Q. What is concrete grading?
- A. Concrete is made from three primary ingredients; cement, water,
and aggregate. Aggregate is typically sand or rock. The cement and
water provide strength and act as the glue that holds the aggregate
together. In general, the more aggregate, the weaker the concrete.
Concrete grade is defined by the strength of the concrete and is measured
in pounds per square inch. (psi). In general, the higher the psi grade,
the more weight it can handle, the more durable it will be, and the
better it will hold up when pressure washed. Concrete used in driveways
is usually 3000 or 4000 psi. In industry jargon, 3000 psi is equivalent
to "five bags of cement per yard mix" and 4000 psi is equivalent to
"six and a half bags of cement per yard mix." As one would expect,
4000 psi grade concrete is slightly more expensive than 3000 psi grade
concrete. However, this price difference is small when compared to
the total cost of driveway replacement.
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- Q. Will my driveway be completed
after the concrete dries?
- A. Concrete does not dry, it sets or cures through a chemical process
called hydration. During hydration, water molecules combine with the
cement to form very tiny crystals. These crystals interlock with each
other as well as the aggregate in the concrete to the concrete's strength.
Water is a necessary part of hydration. If the concrete or the surface
of the concrete dries before hydration fully occurs, the concrete
loses its strength and/or becomes flaky. Therefore, it is very important
to keep the surface of the concrete wet after it is poured.
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- Q. How do I determine the
correct design for my driveway?
- A. In general, water should never puddle on the driveway. If the
house is on a hill, the driveway should channel the water down to
the street or to a storm drain. Residential driveways are usually
four inches thick. In general, thinner driveways are more apt to crack
than thicker driveways.
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- Q. Why are sections of my driveway
different shades or colors?
- A. Unfortunately, due to variation in the color of the raw materials
that make up concrete, colors will vary between batches of concrete.
Color variation is usually not a problem in a complete replacement
job, since all of the concrete usually comes from the same batch.
However, when adding to or replacing a section of an existing driveway,
you should expect color variation. In such cases, the contractor is
at the mercy of the concrete supply company, and the concrete supply
company is at the mercy of the natural variation in raw materials
mined from the earth.
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- Q. I have water accumulating
at the entrance of my driveway, what causes this?
- A. . Misplaced gutters or missing downspouts often dump water alongside
a driveway or sidewalk. Over time, the flowing water may erode the
ground next to the driveway and form a gully. Eventually, the gully
reaches the earth directly beneath the driveway. As the earth beneath
the driveway washes away, the driveway loses its support and is likely
to crack and settle. Before replacing such a driveway, first fix the
water flow proble
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- Q. Who are Concrete Contractors?
- A. Concrete contractors pour driveways and are ultimately responsible
for the work. They usually own the front-end loaders and the forms.
However, concrete contractors almost never make the concrete or own
the concrete delivery truck. Instead, they contract with a concrete
company to supply wet concrete to the job site. Reputable concrete
contractors arrange for the proper grade of concrete to arrive when
they need it. Driveway contractors, like any company working at the
home should carry both workers' compensation and liability insurance.
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