Turning back the clock on your asphalt pavement

 

To understand asphalt pavement maintenance procedures one should first understand what an asphalt pavement is, how it is made, how it is installed and how it ages. Asphalt paving mixtures are all basically similar. They are comprised of aggregate (rock), fines (sand) and a small amount, typically five to six percent, of asphalt oil (AC). 

Various quantities of these components are blended at high temperatures to manufacture the paving material. They are then transported to the job site, run through the paving machine and compacted to provide a smooth wear surface.  Left alone and not properly maintained, the aggregate and sand are not affected appreciably by aging. But the oil or asphalt cement that binds the mixture together starts to break down or age as soon as this oil is exposed to heat when its being mixed. Further exposure to air, water and sunlight combine to cause oxidation, the aging process of asphalt. More importantly, oxidation ages the oil that holds the aggregate and sands together to form a flexible asphalt pavement.

The asphalt oil is made up of asphaltenes and maltenes. The asphaltenes are fibrous, graphite-like materials in the oil that do no break down or oxidize. The maltenes are the tacky, glue-like materials in the oil that effectively bond together the aggregates and sands. The maltenes are the portion of the oil that degrade and oxidize from the pavement.

Sunlight (UV) fractures the maltene molecules and they discharge from the pavement. This is represented in the graying out of the pavement surface. During this process, the oil is losing its ability to bind the surface fines or sand materials that provide the smooth texture of a pavement. These fines will erode from the surface as it is exposed to water. The next step is that the aggregate itself begins to pop out of the pavement leaving you with a gray, pitted and brittle pavement surface.

Water-based coal tar emulsion coatings, or sealcoats, are commonly placed as a pavement maintenance procedure. This has been a standard practice and it was thought that sealcoating would protect a pavement from oxidation and fuel spill or water damage. These claims of protection are simply not true.

Although aesthetically pleasing when initially placed, these coatings are very short lived. They wear off under traffic and it has been determined through government that these sealcoats will crack. Cracking in the coating
allows contaminates as well as the oxidizing factors to permeate the seal and damage the pavement.

A sealcoat will do nothing to replace low maltenes or restore flexibility to an aging asphalt. Simply put, placing a coating on your pavement will not extend the life of that pavement, or postpone overlays or reconstruction.

Let us now introduce you to a treatment that provides unparalleled protection to a pavement from oxidation and water or fuel-spill damage. This treatment will also put back maltenes lost through oxidation. Better put, this treatment will not only stop oxidation (the aging of asphalt), but will reverse it, putting life back into the pavement, therefore extending service and postponing overlays or reconstruction.


The product that does this is Pavement Dressing Conditioner (PDC) Asphalt Rejuvenator. PDC is specified by the Federal Department of Transportation as a coal tar sealer/rejuvenating agent. This material is designed to penetrate into an asphalt oil, providing a fuel and water resistant surface. Now the source of protection for your coal tar is in the pavement, not just on it.

PDC will restore flexibility and durability. Rejuvenation is the softening of a pavement surface and the revitalization of the oils ability to retain the fines and aggregate. The rejuvenation process ages much slower through evaporation of the coal tar rather than the rapid aging of pavement through oxidation.

 Test studies validate the ability of Pavement Dressing Conditioner (PDC) Asphalt Rejuvenator to preserve a pavement, no matter how old it is, and offer a longer lasting, black coal tar protective finish. 


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