Now that we’ve established the importance of road preservation maintenance efforts, here are a few common treatments used to repair and maintain roads:
One of the most common traditional maintenance efforts is known as mill & fill, or mill & overlay. Mill & fill is a worst-first approach that involves completely removing the old, damaged pavement with a pavement mill and replacing it. This method is typically used when the road is past the point of repair. A mill & fill can take anywhere from days to weeks to complete, depending on variables like the weather or the length and width of the road. You can expect road closures and detours when this method is being performed.
A common preservation-based alternative to mill & fill for roads in very poor conditions is cold in-place recycling (CIR). In this cost-effective, eco-friendly process, the top 2 to 5 inches of asphalt is removed and recycled in a continuous train. CIR completely reuses the existing road material to repair and reinforce the road, reducing production costs. Compared to conventional methods, CIR emits fewer greenhouse gasses, almost completely eliminates hauling, adds another 15 to 20 years of pavement life, and speeds up construction times. In fact, recycling can be anywhere from 20% to 50% less expensive than traditional methods. Roads that are good candidates for mill & fill are often good candidates for CIR, so it makes sense why this would be a good maintenance option!
Full Depth Reclamation (FDR) is an engineered rehabilitation technique in which the full thickness of the asphalt pavement and a predetermined portion of the underlying materials (base, subbase and/or subgrade) is uniformly pulverized and blended to provide an upgraded, homogeneous material. Like CIR, full depth reclamation doesn’t require the purchase of new asphalt materials since the roads are reworked by recycling the existing layers. FDR isn’t just used on roads in poor condition. It is often a smart candidate for roads that require more load bearing capacity or could otherwise benefit from a more robust pavement.
For less severe road damage such as cracking, other common preservation efforts include various kinds of seals and thin asphalt overlays. A fog seal is a thin coat of asphalt emulsion that provides a low-cost way to extend the life of a road and protect it from oxidation. On a road with slight to moderate distress, a slurry seal could be a good preservation option to seal cracks, restore the pavement surface, and preserve structural integrity. A slurry seal is similar to a fog seal, but it also has finely crushed rock (called an aggregate) in the mixture. A chip seal, where a layer of asphalt emulsion is laid underneath a layer of aggregate, is a good option for a road with low to moderate cracking. This kind of seal works to fill minor cracks and seal out water. While not as effective for large damaged-areas, sealing road damage before it becomes extreme is a good way to prevent minor cracks from becoming major, making roadway lifespans (and maintenance budgets) stretch farther.
Using preservation methods like these will extend the life of our roads by prolonging their structural integrity and addressing smaller wear-and-tear issues before they become large problems. Plus, preservation can save large amounts of time and money by preventing the need for more drastic and costly repairs down the road (no pun intended).