What is Sealcoating?
Seal coating is a method of protective maintenance to asphalt. The process entails putting a thin, liquid layer on top of the paved surface. It acts like a barrier in protecting the asphalt from potential UV rays damage, rain, snow, and different types of vehicle fluids. This seal coat application does not replace or repair broken areas, although it is applied for protection purposes and will have minor improvement on surface smoothness. This will, because the seal coat is maintained to remain in tack, continue to protect the asphalt underneath it from water, wind, and sun, which is otherwise bound to make the former harden and then crack or even crumble.
Selecting the asphalt
In selecting the proper grade of asphalt for a surface treatment, consider: temperature of the surface to which the treatment will be applied, air temperature, humidity and wind, condition of the surface, and type and condition of the aggregate to be applied.
The use of cutback asphalts in Wisconsin is now strictly controlled. Therefore, rapid-setting (CRS-1, CRS-2, RS-1, RS-2) emulsified asphalts are used most often. Emulsions are a mix of asphalt cement, water, emulsifying agent, and additives.
Seal Coat Asphalt Process
While each sealing company may have its own specific approach, the general seal coating process typically includes the following steps:
Surface Preparation: The pavement is cleaned thoroughly to remove dirt, dust, debris, and loose stones. A clean surface is necessary for good adhesion.
Minor Repairs: Small cracks and potholes are filled to ensure a smoother and more even application.
Seal Coat Application: Apply the seal coat material, usually by squeegees or sprayers, working in all directions to make sure the surface is evenly covered.
Curing Time: The seal coat must not be disturbed for at least 24 hours after application to give time for the liquid to evaporate and leave a durable protective layer. Avoid driving on the surface while curing, and after curing, sharp turns should be made with caution to avoid stationary wheel movements marking the surface.
Optimal Conditions: Sealing is best done between spring and fall of the year when the temperature is constantly above 55°F during application. In addition, for a period of at least eight hours after application, the possibility of rain should be less than 40% to allow for adequate curing. Sealing the coat outside these conditions may result in an ineffective or improperly set coating.
Two Types of Sealcoat
There are two main types of seal coat, and they differ in the type of binder they use.
Refined Coal Tar Based Seal coating
Refined Coal Tar (RTS) is the thick black liquid that is a byproduct of the distillation of bituminous coal.
This type of binder is composed of thousands of chemicals and has a different molecular structure than asphalt. It is not affected by the destructive elements of weather, the sun’s UV rays, salts, oil, gasoline, fats, and other petrochemicals.
Refined Coal Tar was introduced in the 1950s and has been the industry’s most commonly used sealcoating binder until recently.
Asphalt Emulsion Based Seal coating
The main ingredient of Asphalt Emulsion Based Seal coating (AE) is asphalt cement which is derived from the same oils and materials used in producing asphalt.
AE is known to lack resistance to petrochemicals such as gasoline and oil due to being a petroleum derivative and having a natural tendency to be dissolved with them.
However, it has gained popularity due to its superiority in maintaining surface integrity to asphalt pavement, preventing cracks from occurring. Since its inception, AE’s overall performance has been improved by adding chemicals and specialty rubber polymers.
other type:
Acrylic Seal Coat
While asphalt and coal tar are relatively affordable, acrylic seal coats are the most expensive. This option offers high-quality protection like coal tar and without the environmental dangers. However, due to its high cost, acrylic seal coats are primarily used for small parking lots or sports courts. The price tag is too steep for large-scale projects like roadways.
Oil-Based
Although oil-based seal coats are not advantageous, some people still use them. These coats take the longest to dry and cure, sometimes taking up to seven days. They also produce off-putting smells, and they don’t protect well against UV rays. However, oil is naturally water-repellant, which is the main benefit.
Is Seal Coating Truly Necessary?
Although pavement seal coating does not fix existing issues like cracks and potholes, it is significant in avoiding future issues. Property owners and managers who delay seal coating can be left with expensive repairs, such as asphalt resurfacing, which can cost thousands of dollars for new asphalt.
By routinely using seal coating every six years or so, you can reduce long-term repair expenses and enhance the overall functionality of your asphalt. A seal coat in decent condition extends the life of your pavement and prevents serious issues from occurring. Its lower cost provides enormous savings over the long term by avoiding costly repairs down the road.
Seal coat or chip seal
A seal coat or chip seal is a single application of asphalt sprayed on a road surface followed immediately by a single layer of uniform size aggregate. It treats the surface to help prevent surface water from penetrating old, weathered, or cracked pavements. The asphalt seals the old surface and the aggregate carries the traffic. This reduces potholes and slows the deterioration of old asphalt pavement surfaces.
This treatment also renews the surface at relatively low cost and restores skid resistance to traffic-worn pavement. Old roads can be slippery when excess asphalt bleeds to the surface or when traffic has smoothed the sharp edges off surface aggregates. Applying hard, sharp new aggregate in a chip seal will improve friction.
Health and Safety
The main health-related danger of working with seal coating is that the materials are often carcinogenic. So, if workers get exposed to them through skin or lung contact, they can develop cancer and other illnesses. One instance probably won’t do anything, but repeated contact with these toxins can lead to long-term damage.
Coal tar emulsions are the leading contributor to cancer and other health problems, but other materials have toxic chemicals as well, making them hazardous to workers and the environment.
