The lifespan of bituminous pavements has shortened greatly in recent years for a number of reasons. One major cause is the aging of the binding agent bitumen. Asphalt consists of about 94% sand and stones, and approx. 6% binding agent, namely bitumen. Only the binding agent is subjected to an accelerated, natural process of decomposition that results in visible damage after only a short number of years: burst of the grain and the formation of cracks convalesce into potholes and ultimately the complete destruction of the roadway itself.
Now, this development is considered through extensive measures that aim to replace the asphalt layers. However, the asphalt layers are aging significantly faster so that the measures cannot keep up with this progressive effect.
The solution is a preventative approach that we are already familiar with from a number of other fields: preservation.
Practically all materials these days are protected against premature aging, and are thus preserved: steel is galvanized, wood is impregnated via pressure, and so on. Yet we have not yet protected our most crucial economic asset: our roads. That is why in the 1970s in the USA a process for the preservation of asphalt was developed, the effectiveness of which has been proven for decades.
Asphalt is preserved by spraying the current asphalt surface with GPM (Gilsonite Preservative Material). This preservative permeates up to 10 mm into the current coating layer and forms a chemical connection with the current binding agent. This does not alter the texture of the roadway’s surface, and porous coatings do not forfeit their desired traits.
One of the major active components of the previously known preservation agent is gilsonite (also known as "Uintahite", from the state of Utah in the United States of America). Gilsonite is a hydrocarbon that is up to 99% pure and is naturally occurring, sometimes as a raw fossil fuel.
It is particularly resistant against age-related wear (oxidation, heat and UV radiation) and mechanical strain. These characteristics help the preservative protect the current bitumen of the asphalt base against the natural aging process. The typical depletion process of the binding agent is halted effectively for years. At the same time, the preservation effectively prevents the permeation of water into the asphalt, thereby largely impeding water’s harmful effects.
The preservative is utilized at a time when the asphalt to be preserved does not exhibit any significant damage. Depending on the time of preservation, the (remaining) lifespan of the asphalt base can be doubled.