Integral Colored Asphalt
By Irv Howton
The old adage “You can get your asphalt any color you like, as long at it is black,” no longer applies. There are at least two types of color systems that are on the market today to color Hot Mix Asphalt. One system uses a colored cementicious material that is applied to the mat surface and rolled. Often a pattern is rolled in as well. This system coats the surface of the asphalt pavement. The flexibility of this system is that many colors can be used and the patterns can make the mat appear to be stonework. The main disadvantage to this system is that the cost is high and the application requires a new skill set to be used on the job.
The other coloring system has been around since the early 1990s. This system actually colors the material before it is placed and is uniform throughout the mix much like the integral color that is used in concrete. The main advantage to this system is that the whole top lift of the mat is colored using the same techniques that are already used in paving. The disadvantage is that the colors are limited to mainly reds and browns.
Using the second system, the Hot Mix Asphalt is colored by incorporating the powdered additive into the batch plant pugmill during mixing. The amount of color that is added depends on the color that is requested. Lighter colors require more additive to do their job.
In order to get the most square footage of color at the least cost,the integral method is only used on the top 1″ or so of the pavement. The lifts below the top lift can be traditional asphalt. The colored asphalt behaves exactly like the traditional asphalt. It is the same temperature, it paves the same way and it needs to be compacted in the same way.
There are some differences from traditional asphalt,however,that should be considered when building the job. First, all equipment (pavers, trucks, rakes, etc.) must be cleaned. Residue from the black asphalt will become part of the colored asphalt. If the top lift is supposed to be red, then black specs or streaks will not be wanted on the surface. Taking the time to clean the equipment will be worth the effort as there is no “fog seal” to hide the problem.
Second, in addition to cleaning the equipment, all crewmembers’ shoes should be cleaned. While walking on a mat, shoes pick up residue that stays on the shoes as the mat cools. When the new asphalt lift is laid down, it is hot enough to melt the residue on the shoes and right in the middle of the new light brown mat will be the imprint of a size 11-work boot.
As with all jobs, understanding the steps that are needed to do the job right and communicating these steps to the crew will ensure that the customer is satisfied with the job.