Asphalt Pickup

Asphalt pickup has been a long-standing nuisance for paving contractors. When fine particles separate from the aggregate structure and adhere to the surface of a roller,openings are left in the asphalt mat and another step must be added to the paving process As the usage of Superpave asphalt mixes grows, the popularity of pneumatic tire rollers returns. And with the renewed popularity of pneumatics comes increased concern about asphalt pickup.

Pavertrend™ is the most popular application of combating asphalt pickup. Pavertrend™ act as a lubricating barrier between the tires of a pneumatic roller and the asphalt mat. This barrier inhibits the rubber tires and petroleum-based asphalt from bonding.

Rubber & Polymer-modified asphalt hot-mix designs causes increased asphalt pickup issues. Pneumatic tires and liquid asphalt have an affinity for each other because of their respective chemical structures. The rubber in the tires and the petroleum in the asphalt form a chemical bond that causes the asphalt to attach to the tire.

However, a paving contractor doesn’t have to battle the problem of pickup alone. An arsenal of tools is available to reduce the occurrence of asphalt pickup on pneumatic roller tires. These tools help a contractor complete a high-quality project in a timely manner to get a paving job done right the first time.

How to Combat Asphalt Pickup Tire

Releasing the problem

One of today’s most popular methods of combating asphalt pickup involves utilising a chemical release agent. Pavertrend™ work by acting as a lubricating barrier between the tires of a pneumatic roller and the asphalt mat. This barrier inhibits the rubber tires and petroleum-based asphalt from bonding.

When polymer-modified asphalts were introduced to the market and their high polymer content caused increased asphalt pickup issues, paving contractors started looking for a substance that could alleviate this problem. Contractors first used a job site staple,diesel fuel, to reduce pickup.

However, diesel was not a long-term solution for several reasons. First, the fuel raised concerns about possible contamination of job site soil and nearby ground water.Second, the fumes from the fuel could adversely affect the health of the roller operator and other members of the paving crew. Still, the largest barrier to adopting diesel asa release agent was the simple fact that diesel can cut through an asphalt mat, there by reducing its strength and quality. If asphalt pickup is a problem because it damages the mat surface, a substance that further weakens the mat is obviously not a solution. How to Combat Asphalt Pickup Tire In fact, because of the issue’s diesel causes, many state DOT’s (Department of Transport) have banned its use as a release agent.

Looking for a safer and more effective alternative, contractors applied the release agent concept and found success. The lubricating action of the Pavertrend™ allows the pneumatic tires to move across the hot asphalt without inducing pickup.

Pneumatic know-how While the advent of Pavertrend™ has greatly reduced asphalt pickup, release agents work best when the roller is operated properly. In fact, when combating asphalt pickup,proper pneumatic roller operation is just as important as choosing the proper release agent.

How to Combat Asphalt Pickup Tire

Air Pressure:

Correct pneumatic-tire roller operation begins with checking the air pressure in the tires. Ensuring the air pressure is correct helps a roller operator reduce the possibility f material pickup. If one tire is under-inflated, the lack of pressure will cause the asphalt to bind to the tire instead of the mat.

Warming up Tires:

Another crucial step in proper operation involves warming up the tires to 100°C - 120°C temperature near that of the hot-mix asphalt before applying the roller to the asphalt.If the tires are near the temperature of the asphalt, the petroleum in the asphalt will stay hot enough to act as a lubricant for the rubber tires, much like a release agent.As soon as the tires cool to a temperature below that of the hot asphalt, aggregate will begin to adhere to the rubber.

An appropriate tire temperature can be achieved by first running the roller up and down a compacted surface to begin building heat in the tires. Once this temperature is reached, it is important to keep the roller moving to maintain the heat in the tires. Even if the rest of the equipment in the paving train stops, the pneumatic roller should continue running over the asphalt at 3 to 4 km/h. Pneumatic tires can cool quickly and begin to induce pickup, so it is imperative the operator keeps the roller moving to greatly diminish the chance the problem will occur.

Heat Retention Shields & Cocoa Mats:

Pneumatic-tire roller manufacturers have realised that even with Pavertrend™ and proper roller operation, contractors can still feel the pain from asphalt pickup. In response, manufacturers have developed tools that, when added to the roller, help reduce the occurrence.

Heat retention shields are one of the tools available to alleviate asphalt pickup. These shields consist of a rubberised material that acts as an insulator to keep heat around the tires. Asphalt pickup usually begins on the outside tires of pneumatics, as these tires cool faster because wind is constantly blowing on them. When the tires cool, the hot asphalt is more apt to stick to the rubber. By using heat retention shields, the wind cannot reach the outside tires, keeping the heat from the asphalt mat around them.

Cocoa mats also are available to help eliminate the beginnings of asphalt pickup.These are attached to the roller’s frame and lie against each tire to loosen any aggregate that sticks to the rubber. Since even a small amount of asphalt on the tires will induce more pickup, the use of cocoa mats can help prevent minor build-up from turning into a major problem.

Silicon Based Tires:

Asphalt pickup also continues to diminish thanks to engineering developments in the pneumatic tire industry. Some pneumatic tire manufacturers have taken steps to reduce pickup headaches by developing tires embedded with a silicon-based substance that produces a “non-stick” effect and repels hot asphalt.

With the help of these new tools and technologies as well as old-fashioned roller know how, contractors continue to get a better handle on the problem of asphalt pickup.

Pavertrend™

Improves the quality of the finished product. Allows contractors to focus, rather than wasting their time in solving asphalt pickup issues.