UX Design 8hours

Asphalt is composed of stone and asphalt cement – a binder that holds it together. It is made in a hot tumbler where the binder is applied to the stone. The mix is then transported by truck to the lay-down site where it is placed and compacted. It is compacted to a point that leaves small voids. This “honeycomb” design provides flexibility and allows the binder to migrate as the surface settles. This openness also allows environmental elements to enter the pavement.

Oxygen in our air is the major deterrent to long life for well designed asphalt pavement. The oxygen in our air as well as UV rays from the sun, and water from rain and runoff constantly stress the integrity of asphalt pavements. Oxidation can begin immediately, even while the asphalt is being made. The asphalt binder covering the stone is so thin that oxidation reaction occurs at a fast rate – this is called Short Term Aging. Oxidative hardening that occurs after the asphalt is places is called Long Term Aging. It occurs slowly throughout the life of the pavement. Oxidation affects the asphalt binder.

Asphalt binder is composed of two petroleum fractions, asphaltenes and maltenes.  Environmental factors, like oxidation, cause maltenes to convert to asphaltenes. As the ratio of asphaltenes in the binder increases the flexibility of the asphalt is reduces and the result is dry and brittle pavement. To be effective, a rejuvenator must be able to penetrate to a limited depth to restore the balance of maltenes and asphaltenes.

Cracking

As the binder hardens, the top surface of the asphalt becomes brittle. When traffic passes over it and lowers the levels of flex, the top develops hairline cracks. This top down cracking is a result of oxidation and signals an immediate need for rejuvenation.

Moisture Penetration

As the pavement ages, it becomes more susceptible to water damage. After a rain, the asphalt surfaces stay wet longer than surrounding areas.

Contaminant Degradation

Asphalt surfaces on roads and in parking lots are susceptible to damage from oil and gas leaked by parked cars. Airport ramps are damaged by aircraft refueling operations. These areas show up as dark spots that soon ravel, lose aggregate and become potholes.

Color Change

The color of pavement changes from black to grey and then white. This is directly due to oxidation.

Raveling Loss of Aggregate

Once the binder looses it’s glue-like qulaities, the pavement begins to ravel. Raveling is a loss of aggregate. This signals a need for immediate rejuvenation!

To measure the effects of embrittlement and aging, the viscosity of the asphlat binder is measured. Viscosity measurements are gathered in the top 3/8 inch of an asphalt core. The aggregate is separated from the binder and a viscosometer measures the thickness of the remaining binder. The results are reported in centipoise.

Given what we’ve learned about asphalt, we know it’s important to protect asphalt from oxidation. We also know we need a solution that penetrates the asphalt to ensure viscosity of the binder is restored to a depth of 3/8 inch. Oxidation begins at early in the life of asphalt so immediate protection is ideal. 

Luckily there is a solution! 

Paverx Asphalt Rejuvenator can be applied to penetrate new or old asphalt and restore the balance of maltenes and asphaltenes effectively restoring viscosity and halting the aging process!