Sealcoating is one of the most important elements of a pavement management plan. Air,
sunlight, and moisture are a major cause of surface deterioration. Progressive
weakening, erosion, oxidation, and unravelling due to water and weather
damage can reduce pavement thickness by as much as 50%! If not kept in
check, costly repairs or resurfacing may be necessary.
A Closer Look at Seal Coating
Asphalt is a very complex mixture of chemicals with very little saturation
in their molecular structure.
The structure is considered “open chain” or “asphaltic”
which provides easy access to weather, salts, and chemicals which in turn
disintegrate the asphalt itself. This will result in loss of its original
properties such as binding and waterproofing. Typically, the first visual
sign of this loss is the “graying” of the asphalt from its
original rich black look.
Asphalt is derived from the petroleum distillation process and when additional
byproducts meet, such as oils, fats, grease, mineral spirits, etc. they
have a natural affinity to join together. So when automotive oil or gasoline,
both petroleum distillates, leak onto the pavement, they work to easily
dissolve the similar chemicals in asphalt. These problems are associated
primarily with off-street areas, such as, parking lots, minor roads, airport
aprons or runways, service stations and home driveways.
These all have low levels of traffic flow. Highways and major streets have
the advantage of continuous rolling traffic which creates a kneaded oxidation
effect back into the pavement, therefore, creating a longer visual and
strength advantage. Eventually all asphalt life is exhausted and the aggregate
begin to unravel, evolving into minor cracks which widen and deepen with
time. If water seeps into the cracks it allows the load capacity to falter.
This then results into rutting, shifting, and serious alligatoring of
Off-street pavements do not have the advantage of the kneading action.
The surface layers of off-road pavements are under continuous attack from
the weather and other destructive elements, eventually developing minor
surface cracks. It is logical to conclude that off-street pavements can
be preserved by a protective sealcoating that resists the attack of elements
that destroy the asphalt anyway.
Currently, there are
2 types of sealcoating materials – those made from refined coal tar and those made from asphalt.
Atlanta seal coating experts, Blackjack Paving, recommends a
refined coal tar sealcoat. Refined coal tar molecules have a closed ring or aromatic structure with
a minor degree of un-saturation. This molecular structure doesn’t
allow the elements of weather to affect the property of coal tar.
They act as a tough barrier for asphalt surfaces. The asphalt emulsions
do not provide the resistance to color fading, salts, and petrochemicals
such as, oils, fats, grease, and solvents such as the refined coal tar.
Beautification When covered with a dark black sealant, pavement looks and wears like new.
Parking lot sealcoating helps to project a positive image of the company, facility, or residential complex.
Slows oxidation and water penetration
Sealcoating fills surface voids, which reduces exposure to oxygen and
UV rays and reduces the depth to which oil or gas can penetrate the pavement.
Sealcoating acts as a waterproofing agent, minimizing the rate at which
water enters pavement. Without it, water can permeate more freely resulting
in freeze/thaw expansion and contraction of the pavement.
Sealcoating resists oil and gas spills
Gasoline dripping from a topped-off fuel tank during hot weather can soften
and break down unsealed asphalt pavements. Coal tars used in sealcoat
are impervious to gas and oil spills.
Asphalt sealcoating is easier to clean and maintain
Sealcoats fill surface voids while coating the pavement surface. The resulting
smooth and even texture makes the surface easier to maintain year-round.
For example, snow is easier to remove from a smooth surface, and sweeping
is far more effective on a smooth surface.
Sealcoating increases pavement flexibility
Sealcoat brings a dark black color to the pavement. The blacker it is,
the more heat a pavement draws from the sun. And, the hotter it gets,
the more pliable it becomes, which helps it to withstand traffic without cracking.
Protects asphalt from pressure washing
Restaurant parking lots often extend to areas near dumpsters, where food-processing
machines are pressure washed. Food waste near the dumpsters may also need
to be washed away if it can’t be swept away.
Sealcoating protects asphalt cement from the high-volume water pressure and detergents used in pressure washing.
Asphalt sealcoating is cost effective
The price of asphalt will always be affected by crude oil prices, which
fluctuate when supplies vary. Sealcoating preserves asphalt for pennies
per square foot.