FEATURE
You Only Get One Chance at
COMPACTION
We’ ve all driven past a parking lot or roadway that looked brand new just a few years ago, only to wonder why it’ s already beginning to crack, ravel or show signs of wear. While there are plenty of factors that influence pavement performance, one of the biggest often happened on the very day the asphalt was placed. A paver can be fine-tuned. Screed settings can be adjusted. Material delivery can improve as the day goes on. Even small issues that pop up early in the project can often be corrected before the last truck leaves the job site. Compaction is different. Once the asphalt begins to cool, the opportunity to achieve proper density starts disappearing. Miss that window, and there’ s no second chance. No amount of extra rolling after the mat has cooled will make up for density that was never achieved in the first place. That’ s why experienced paving contractors know compaction isn’ t simply another step in the paving process— it’ s one of the most important factors in determining how long a pavement will perform.
Why Density Matters
To the average driver, a newly paved parking lot or roadway looks finished as soon as the roller leaves the mat. Contractors know better. Most pavement failures don’ t happen overnight. They develop little by little until one day someone notices the cracks, the loose aggregate or the wheel paths that weren’ t there before. By then, the opportunity to prevent many of those problems has long passed. What matters isn’ t just how smooth the pavement looks on day one. It’ s how well that pavement holds up after years of traffic, changing weather, heavy loads and repeated freeze-thaw cycles. Proper compaction reduces the amount of air trapped inside the asphalt. Those remaining air voids play a significant role in determining how the pavement performs over time. Too many voids allow water and air to penetrate the surface, accelerating oxidation of the asphalt binder and weakening the pavement from the inside out. It’ s often a slow process. The pavement may look perfectly fine when the project is complete, but months or years later, the signs begin to appear— raveling, cracking, rutting, moisture damage or premature deterioration. Many of those problems can be traced back to compaction.
The Compaction Window Is Short
Asphalt doesn’ t stay workable for very long. Ask just about any roller operator, and they’ ll tell you the same thing— the clock starts ticking the moment the mix hits the ground. Every decision after that has to keep pace with the cooling asphalt. Every minute after the mix leaves the paver, temperatures continue to fall. As the material cools, it becomes increasingly difficult to achieve the density needed for long-term performance. That’ s why roller operators, paver operators, truck drivers and the entire paving crew have to work together. Good compaction isn’ t the responsibility of one person— it’ s the result of a well-coordinated operation.
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