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EDUCATION
Facts
You Should Know About Asphalt
Asphalt
is not as tough as it looks
How
do I best take care of my new asphalt pavement?
Asphalt
Fabric Overlay
History
of Asphalt
Facts
You Should Know About Cracks
Preventive
Maintenance Planning
Economics
of Sealcoating 1998-2013
Facts You Should Know About Asphalt
A good asphalt pavement
will not last forever; external factors destroy the asphalt
oil that binds it all together. Slowly at first, quickly
as time goes on.
As soon as the freshly laid
hot asphalt pavement mix begins to cool, so also begins
the aging process which will eventually rob the pavement
of its life. When oxygen and water, which constantly bathe
the pavement, start to combine with the asphaltic binder
of the pavement, a chemical change takes place. At first,
this process is necessary for the pavement to become hard
and firm. Later, if this process is not arrested, a complete
deterioration of the asphaltic binder will take place
and reduce the pavement to a layer of loose stone. The
asphalt binder is essentially what differentiates a gravel
road from a paved road.
The destruction rate of
an asphalt pavement varies:
Heat & Sunlight will
accelerate the deterioration process; salt will act as
a catalyst. Water which penetrates the surface can get
into the base course to cause trouble, and at the same
time start oxidizing the asphaltic binder inside the pavement.
A more dense mix will not oxidize as rapidly as a coarse,
open pavement. A thicker lift of pavement will keep its
life longer than a thin one.
Automobile & truck traffic
create the danger of gasoline and oil spillage, which
will soften the asphalt and lead to its breakup.
Our cold climate enhances
the danger of water being caught in the pavement and freezing.
This can break individual pieces of aggregate apart, or
it can break out large sections.
Sealcoating the asphalt
pavement with Micro Pave 2000, a slurry sealcoat that
has been scientifically developed by Lambert Bros. Paving
in the laboratory to address western Canada's climatic
conditions, can protect the pavement against all these
destructive factors.
Lambert Bros. Paving can
inspect, evaluate and give a free estimate when you call
(403) 287-3252, so call today.
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Asphalt
is not as tough as it looks
Asphalt pavements such as driveways and parking lots are
continually being constructed but unfortunately are not
lasting as long as they used to. Many of us remember pavements
lasting 15, 20 years or more with little to no maintenance.
This is not the case anymore. Like many things, asphalt
too was made better in the past. The
day your asphalt pavement was installed, it began to
deteriorate.
Just now it happens faster. Just watch the colour fade
from rich black to oxidized grey in no time. There are
two reasons for this drastic decline in an asphalt lifecycle.
1) Asphalt
Asphalt is not what it used to be. Due to technological
advances in the refining process more and more of the
high value resins and oils have been extracted.
These resins and oils have a much higher dollar value
alone than in asphalt. They can be used in hundreds
of
products from plastics and synthetic rubbers to perfumes
and cosmetics. The asphalt in our roads and parking lots
is
merely the glue that holds the rocks together. The more
they refine from asphalt, the poorer the glue, the poorer
the pavement.
We are continuously rebuilding and repairing our roads,
parking lots and driveways with asphalt of lower quality,
which continues to increase in price.
2) Oxidation
Since the asphalt binder is not of the quality that it
was in the past, given this loss of resins, the asphalt
is more susceptible to oxidation from the weather, thus
accelerating the deterioration process. Oxidation happens
when oxygen, in the air and water, chemically attacks
the asphalt binder causing it to break down.
Ultra-violet rays from the sun cause further breakdowns
of asphalt making it brittle. Calgary's freeze-thaw cycles
literally tear asphalt pavements apart from the inside
out. A more dense mix of asphalt, and asphalt that has
been properly compacted, will not oxidize as rapidly as
a coarse, open pavement. A thicker lift of pavement will
hold up longer than a thinner one.
Preventive Maintenance Planning is the
solution or counter balance to keeping your asphalt
up
to speed for longer. Neglect your asphalt and it quickly
becomes unserviceable and we will not go into what kind
of an image that projects. Suffice to say that repairs
at that point can be extensive. And expensive. It is
much
more economical to maintain a pavement properly than
to be faced with what is inevitable with neglect. This
is
true with most things: your health, your car, relationships,
your home, etc.
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Asphalt
Fabric Overlay?
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When
a parking lot or driveway begins to develop widespread
surface cracking due to sub-grade failure, an asphalt
geotextile fabric is a reliable alternative to costly
excavation and replacement of the cracked and deteriorated
asphalt.
Most people have the misconception that asphalt
is watertight.
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It is not, and most asphalt failures arise from water
seeping down into the gravel base and weakening the foundation's
shear strength. Once this happens, it is not long before
surface cracks (alligator or fatigue cracking) appear
due to the weight and flexing of the pavement. If the
base is wet and soft the asphalt is going to flex more
than if the base was dry and solid. As the asphalt ages
it loses some of the black oil that keeps it flexible.
When it turns grey in color it is more rigid and more
prone to cracking, which in turn allows more water to
seep in.
Pavement cracking is the most visible indicator of pavement
distress. Simply paving over top of existing asphalt that
has cracks in it will not hide those cracks for long.
The cracks will reappear in the exact same places, depending
on the thickness of the overlay, usually within a year.
This phenomenon is termed reflective cracking, the propagation
of existing cracks from old or existing pavement into
the new overlay.
Reflective and fatigue cracking are two of the most significant
factors in pavement deterioration. These cracks begin
at the base of the pavement and work up to the surface.
It is caused by shear and tensile stresses in the asphalt
layer brought about by traffic loads, change in temperature,
expansive sub-grade soils, moisture changes, existing
crack and joint movements in the underlying pavement.
This cracking is bound to happen but these cracks will
take much longer to reappear if an asphalt fabric overlay
is employed rather than a simple slurry seal or just an
asphalt overlay.
The
use of a geotextile paving fabric will provide a medium
that absorbs the stress related to the old pavement cracking.
This system is very effective, unless there is significant
vertical or horizontal movement in the cracks (greater
than 0.002 inches).
The paving fabric will also create a moisture barrier
that will prevent water from passing through cracks, joints,
and porous pavement itself, keeping the aggregate base
course and foundation intact and strong.
Thermal cracking is another common type of crack caused
by actual expansion and contraction, mostly within the
top layer of asphalt, such as an overlay. These cracks
are unavoidable and will not be prevented by the underlying
paving fabric layer. The waterproofing benefits of paving
fabric generally remain intact even if thermal cracking
occurs. It is still recommended to have all cracks filled
with an elastomeric (rubberized) compound.
Long-term
field evaluations have shown that the proper use of paving
fabrics in asphalt overlays can increase pavements lifecycle
by up to 50%.
http://www.mdot.state.ms.us/research/pdf/PavFabr.pdf
Utilizing asphalt fabric overlays will reduce maintenance
cost and improve the effectiveness of your management
system without the need to reconstruct, provided it is
caught in time.
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How do I best take care of my new asphalt
pavement?
There are a few things you should know about freshly paved
driveways and parking lots:
Asphalt needs 48-72 hours to cure depending on the temperature
and humidity. It is important to keep people, cars and
bikes off the new pavement during that time. Actually,
the asphalt will continue to cure for the next 6 to 12
months but you do not have to wait that long to use the
new surface.
Since the asphalt will be pliable until it has hardened
or fully cured, it is important to avoid the following:
- Parking
your car in the same spot every time.
- Parking
motorcycles and bicycles on the driveway where kickstands
can penetrate the surface.
- Parking
a trailer or RV on the pavement without putting a
piece of plywood beneath each wheel and trailer hitch
to evenly distribute the weight.
Temperature
changes will cause the ground to expand and contract causing
the pavement to crack. This is the nature of asphalt and
is the first step in pavement deterioration. These cracks
should not be ignored! They need to be sealed by a professional
as soon as possible to prevent water damage and further
deterioration of the pavement. To
extend the life of your asphalt pavement, it is recommended
that you sealcoat the surface approximately 6 months to
a year after the paving is completed. Sealcoating will
prevent the oxidation and will resist ultraviolet rays
and gas/oil spills.
- Oxidation
occurs when the asphalt oil hardens due to exposure
to oxygen. This causes cracking allowing oxygen and
rainwater to penetrate the surface causing further
deterioration of the pavement. Sealcoating will protect
the surface from exposure to oxygen and help prevent
the surface from cracking.
- Ultraviolet
rays will cause the pavement to crumble by breaking
the links between the carbon bonds. The sealcoating
will protect the surface from the UV rays and prolong
the life of your asphalt pavement.
- Gasoline
and oil spills will penetrate the asphalt causing
it to soften. Sealcoating will give you a little
more time to get it cleaned up before the damage
is done.
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Facts
You Should Know About Cracks
A good
asphalt pavement seldom wears out; external factors destroy
the asphalt oil that binds it all together. Slowly at
first, quickly as time goes on.
As soon as the freshly laid
hot asphalt pavement mix begins to cool, so also begins
the aging process which will eventually rob the pavement
of its life. When oxygen and water, which constantly bathe
the pavement, start to combine with the asphaltic binder
of the pavement, a chemical change takes place. At first,
this process is necessary for the pavement to become hard
and firm. Later, if this process is not arrested, a complete
deterioration of the asphaltic binder will take place
and reduce the pavement to a layer of loose stone. The
asphalt binder is essentially what differentiates a gravel
road from a paved road.
The destruction rate of
an asphalt pavement varies:
Heat & Sunlight will
accelerate the deterioration process; salt will act as
a catalyst. Water which penetrates the surface can get
into the base course to cause trouble, and at the same
time start oxidizing the asphaltic binder inside the pavement.
A more dense mix will not oxidize as rapidly as a coarse,
open pavement. A thicker lift of pavement will keep its
life longer than a thin one.
Automobile & truck traffic
create the danger of gasoline and oil spillage, which
will soften the asphalt and lead to its breakup.
Our cold climate enhances
the danger of water being caught in the pavement and freezing.
This can break individual pieces of aggregate apart, or
it can break out large sections.
Back to Top
Preventive Maintenance Planning
Asphalt parking lots
require yearly checkups. Preventive maintenance
is necessary in order to get the most out of your
pavement. These decisions on pavement repairs and
maintenance generally involve a large amount of
money and are unfortunately made with little or
no professional knowledge and with little or no
data as to how the improvement will perform in the
long run.
Lambert Bros. Paving offers pavement evaluations
and 5-15 year budget planning free of charge. We
will evaluate the condition of the asphalt and work
with you and your budget to develop the best plan
of attack to (1) get your pavement back up to par
or (2) perform the routine preventive maintenance
your pavement will need to remain up to par.
When determining the best plan for any pavement
we need to ask questions like: Can the pavement
be sealcoated? Can it be patched, crackfilled and
sealed? Does it need an overlay or total reconstruction
starting from the base? Whatever the situation we
will be able to assist and provide you with good
advice and honest information.
Here are some other things we at Lambert Bros. Paving
consider:
A. If pavement repairs are required, to what extent
will patching be more beneficial compared to a complete
resurfacing of the entire pavement area.
B. If the pavement is dull and rough but still sound,
then it may benefit from a slurry sealcoat such
as our Micro Pave 2000. This is a very economical
solution to aging asphalt given that it is generally
1/5 to ¼ the cost of a 1-2 inch asphalt overlay
and will last just as long.
C. Any area of the surface that is either "heaved
up" or "depressed down" should be
completely reconstructed starting from the base.
D. Was the pavement designed for the loads it is
carrying? Often a parking lot was paved with two
inches of asphalt, which is enough to support cars
and light trucks, but not the load garbage trucks
and delivery trucks carry. Maybe only those areas
used by these heavier trucks will need to be reconstructed
to support the heavier load.
E. Has the use of the building the pavement is serving
changed? From an auto parts store (light duty loads)
to a castings factory (heavy-duty use)? The pavement
may need reconstruction.
If it is determined that the pavement is sufficient
(may need some repairs) for coating then we will
"walk over" the entire surface looking
for:
1. BASE PROBLEMS
a. Grade depressions- "Birdbaths", (standing
water on the pavement). Water is asphalt's biggest
enemy. Standing water will eventually destroy the
asphalt in this area. The problem is most commonly
caused by frost expansion in the gravel base or
in the sub-grade. At a minimum these areas should
be dug up and full depth patched. The long-term
solution is to resurface the area so there is not
any standing water.
b. Dumpster areas: If the pavement has failed because
these areas were under designed, the pavement should
be reconstructed from the base up.
c. Water seeping up through the crack (on a dry
day): This may indicate a drainage
problem under the pavement. Do not fill these cracks
with any type of crackfiller or sealer. It would
be
a waste
of
time and money.
2. CRACKS
All pavement failure starts with a crack. Asphalt
cracking is caused primarily by the effects of sun
and moisture and ground movements. Once the crack
is open, moisture is able to reach the pavement's
subsurface and soften it, or freeze and expand it.
Soon the pavement begins to deteriorate around the
crack, creating a larger problem. Proper attention
to the cracks will prevent the problems from spreading
and double the life of the pavement. Treating the
problem while it is still small will pay big dividends
later by delaying costly resurfacing.
a. Minor cracks: Less than 3/8 inch wide are routed
to provide a reservoir for our hot applied elastomeric
sealant.
b. Structural cracks: Cracks usually wider than
1/2 inch that extend from one edge of the surface
to the other. All cracks wider than one half (1/2)
inch but less than one (1) inch should be cleaned
and filled with hot applied elastomeric crack sealant.
c. Big Cracks: Cracks wider than one (1) inch should
be patched with hot mix asphalt.
3. PAVEMENT SURFACE PROBLEMS
a. Raveling or very porous asphalt: Stones have
come out of the surface or the surface has a very
"rough" texture. If the asphalt is not
sealed, it will degrade rapidly. In severe cases
an overlay may be required.
b. Alligatored areas: Interconnecting cracks forming
a series of blocks resembling an alligator's skin.
This problem is usually caused by not maintaining
the asphalt or a base failure problem. The problem
areas should be removed and full depth patched.
c. Oil spots: Prior to coating these areas, (if
the asphalt under them is sound, use the blade of
a knife or thin screwdriver to check this out) prime
them with a water based, acrylic oil spot primer.
d. Grass growing onto the edge of the asphalt: Before
coating or Crack Filling the grass must be removed.
e. Old or badly dried out asphalt: Pavement that
is usually several years old that has never been
coated and has a dull gray appearance should be
cleaned and rejuvenated with two or three coats
of Micro Pave 2000.
f. Special Cleaning Problems: Deposited mud, tree
sap, berry stains, etc. must be scrubbed off the
asphalt for the coating to adhere properly. An acrylic
oil spot primer should be applied prior to coating.
g. Previously coated asphalt: If the asphalt has
been coated before with refined coal tar emulsion,
or asphalt emulsion sealer, use of Micro Pave 2000
should not cause problems provided the sealer has
not cracked. If the sealer has cracked, then sealing
over it may not prevent the cracks from resurfacing. |
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