Posts Tagged ‘pavement maintenance’

Asphalt Seal Coatings

Now some people will tell you that rejuvenation is snake oil and is a waste of money and that a good seal coating is the way to go. Now let’s take a serious look at some of the seal coating systems available for pavement maintenance.  Seal coating systems are designed to seal off the surface of the asphalt mat filling in the voids of the pavement so as to provide a tough wearing surface that will prevent any water from penetrating the mat.  By keeping the surface sealed, a seal coating is keeping the damaging ultra violet of the sun and the elements of the weather off the pavement, while also keeping sealed into the asphalt mat the necessary oils that are required to keep the asphalt mat flexible and healthy.  The drawback to a seal coating system is that once it begins to wear off the surface it no longer provides any protection from the elements in the areas where it has worn off the surface of the asphalt pavement.

Most seal coating systems are mineral filled and rarely have more than 20% bitumen content which is normally only enough bitumen to bind the mineral to the pavement and cover the pavement surface.  This low bitumen content in conjunction with the absence of any light oils or maltines prevents a seal coating from providing any rejuvenation to the asphalt pavement.

One of the most popular seal coating systems across the country is Coal Tar Pitch Emulsified Seal Coating.  Coal Tar Pitch is generally emulsified with water and mixed with a mineral aggregate and/or sand to give the product body and wear-ability.  The major benefits of coal tar is that the product is fuel resistant and generally will provide superior abrasion resistance therefore it will wear and look cosmetically appealing for a longer period of time.  How ever, Coal Tar Seal Coating does normally begin to wear within a year of application and once it begins to wear off the surface it provides no protection to the asphalt mat in the areas where it has worn off.

Coal tar pitch is a by-product of the coking process of coal used in steel mills.  Like petroleum crude it is refined through a distillation process to produce products like xylene, benzene, creosote, and several other types of products, but like asphalt it is the black sheep of the coal tar pitch industry.  Unlike asphalt, coal tar pitch is in no way chemically or otherwise compatible with any type of petroleum product including asphalt.  Due to this reason coal tar pitch cannot provide any rejuvenation at all to an asphalt pavement.  In order to get coal tar to properly adherer to asphalt pavement generally a polymer additive needs to be added by the applicator prior to application to prevent the sealer from delaminating from the pavement surface.  So, the question is why put a product that is not compatible with a petroleum product on a petroleum product such as an asphalt mat.  The answer is a coal tar is generally more cost effective.

Coal tar also has other drawbacks.  Coal tar contains benzene along with several other listed cancer causing compounds.  In addition, the main issue with coal tar is the fact that the vapor of the product is carcinogenic and can cause serious health problems with continues use.  Some of the early signs are burning of the skin similar to what happens when one lets gasoline dry on the skin.  It has been documented by the National Institute For Occupational Safety and Health (NIOSH) in report No. NIOSH-78-107 that states: “Vapors can cause serious lung problems resulting in cancer.”  This hazard will remain present as long as the product gives off a vapor that one can smell.

Due to obvious health and environmental concerns the use of coal tar pitch has been restricted is some states such as the state of New Jersey and the state of New York.  It has been banned in the state of California and the city of Austin, Texas just to name a few.

An alternative to coal tar pitch is asphalt based emulsified seal coat.  Asphalt based emulsified seal coatings are similar to coal tar in the fact that most are mineral filled and are applied and perform in the same fashion; however, asphalt is used as the binder.  Asphalt based emulsified seal coatings do not have the  health hazards associated with coal tar.  However, asphalt based seal coatings tend not to wear quite as well as coal tar and if fuel resistance is desired a vinyl latex must be added to the product which results in increased cost per gallon.

-Todd M.

Call Love’s Enterprises LLC today for Denver asphalt maintenance services – 303-816-9090

Asphalt Maintenance Through Rejuvenation – Denver Colorado

Proper asphalt maintenance is essential if maximum pavement life is to be expected.

The concept of rejuvenation is to introduce into a healthy asphalt pavement a property that is not already present to enhance and prolong the life of the asphalt binder therefore extending the life of the asphalt pavement.

Rejuvenators are designed to penetrate deep into the top surface of asphalt pavement introducing into the asphalt the binder, the required maltenes, and polar compounds necessary to keep the fines and the small aggregate on the surface of the pavement bonded together so as to prevent raveling of the top of the asphalt pavement. Rejuvenation keeps the asphalt binder healthy and results in longer pavement life by keeping the fines in place and not allowing the course aggregate to become exposed.

With today’s high yield refining processes such as the hydro-treater and the catalytic cracker, the quality of available asphalt’s are not what they use to be.  The problem is that these efficient refining processes are taking too many of the light ends or maltenes out of the asphalt, which are necessary for proper binder performance.  It is getting increasingly more difficult to acquire good quality asphalt base stocks to produce quality asphalt pavements.

Asphalt is basically the black sheep of the petroleum industry.  It is a low yield byproduct from the manufacture of high end products such as styrene, polymer’s, gasoline, fuels and lube stocks, which are high end, high profit products.  Therefore it is natural to assume that a refiner would develop more efficient process’s to produce more of the high profit products per barrel of crude oil.  One would figure this is “good business.”  However, this “good business” practice has resulted in lowering the quality of today’s asphalt base stocks.  This is why proper pavement maintenance through rejuvenation is essential in today’s asphalt paving industry.

Pavement Rejuvenation is not a new concept.  It has been around for about forty years.  There has been several products introduced into the industry over the years and several have gone the way of the Dodo.

Asphalt pavement is like the human body.  It is easier to keep it in good shape, rather then to let it go to heck and then try to rebuild it.

The proper way to begin pavement maintenance through rejuvenation is to start with a healthy asphalt pavement and keep it that way.  it is generally recommended to apply a rejuvenator sometime between 3 to 6 months after the new asphalt pavement has been laid.  This introduces into the new asphalt mat the additional binders necessary to keep the fines in place thus protecting the base aggregate in the mat and helps keep the mat flexible.  Then after about three to four years apply another application of the rejuvenator to reintroduce the compounds necessary to help maintain the life of the pavement.  Continue to reapply a rejuvenator about every four years through the life of the pavement.

Utilizing this method, it has been proven that with proper pavement maintenance through rejuvenation in conjunction with a properly designed crack sealing program it is possible to extend the life of primary and secondary roads up to three to five years.

In parking lot and driveway applications asphalt life has been extended up to ten years or more in some cases.

Todd M-

If you have a parking lot or driveway in or around Denver in need of asphalt maintenance Contact Love’s Enterprises LLC today for a free estimate.