By Brian Hofstrom
Infrared technology has proven to be an effective method of repairing asphalt defects. Infrared Road Repair (IRR) is becoming a big business in many city, state and local markets.
The overall process is very simple on the surface, yet complex when you get into the details. To properly repair asphalt pavement using this technology you must be aware of a few important factors that will aid in a successful repair and having a happy customer.
To get started, here are ten topics you should know prior to beginning IRR:
The Basic Principles of IRR
1. IRR is simply the absorption of radiation (heat) into the damaged asphalt to aid in removal. The next step is to replace with new or reclaimed material and reheat to bond the patch with undamaged areas.
2. Proper heating of asphalt is affected by a number of factors. One must always keep in mind that multiple layers must be heated individually and raked off before the lower level can absorb sufficient heat for removal.
3. The percentage and properties of asphalt have an effect on heating times. Polymer grades, mix designs and the age of the material play a very important role. For example, aged (white) asphalt will not absorb heat as well as new (black) material would.
4. Moisture should be avoided while doing IRR. While water can be evaporated using the IRR, during evaporation the heat could very quickly become excessive and damage areas of the asphalt while a more porous section remains wet.
5. Both wind and ambient temperature will largely affect the heat times as well as the time the material will remain workable during the repair.
6. Patch prep is a very important step in the process to obtain a lasting repair. Once the old material has been heated and removed, the edges should be squared off and tapered. The tapered edge allows for more surface area and ensures a good bond between new and old areas.
7. Add new asphalt to the repair. If using new and reclaimed asphalt in the repair, care must be taken to mix the two throughout the repair. Raking the asphalt into the repaired area will ensure new and old material will not become segregated.
8. Rejuvenators are used to replace the maltenes (the light oils of the asphalt cement) that are oxidized out of the material over its lifetime or during the IRR process. Rejuvenators may also be added prior to heating aged (white) asphalt to turn it black, which will lessen heating times.
9. Subgrade failures that are not repaired will only lead to future failure of the surface grade. For example, alligator cracking will look like it patched well using a surface-only repair. However, it will quickly succumb to the failure below and your patch will fail.
10. Heat shields can be used. Many times, state and or local regulations will not allow heating near sewer or drainage components. When the need arises to avoid heating a specific area, a thin sheet of aluminum can be used to “deflect” the IR away by simply placing it on top of the area to keep cool.
Once you and your employees learn the basics of IRR, a simple process, it still takes on-site training to be effective. If a new employee is sent out to do IRR and does not understand the principles of the process, the repair as well as the customer suffers.
Brian J. Hofstrom is the Terminal Manager of S&Y Terminal, LLC in Owensboro, Kentucky.