There's More to Paving Than Sidewalks

Asphalt Compaction Factors To Be Aware Of

No other aspect of asphalt installation determines the ultimate performance of the pavement quite like compaction. An insufficiently or unevenly compacted surface will tend to develop problems at a much quicker rate. Whether you work in the paving industry, or are simply a homeowner hoping to learn more, if you would like to know more about asphalt compaction, read on. This article will discuss two critical factors that influence the compaction of asphalt.

Composition

Asphalt mixes vary immensely, with different blends each having their own particular strengths and weaknesses. The makeup of a specific mix must be tailored to account for its placement, behavior, intended use, and prevalent weather conditions. Certain mixes contain additives to promote desirable characteristics. That said, all asphalt mixes contain at least two common ingredients: distilled petroleum products and gravel aggregate. Yet even these ingredients may vary, whether in terms of size, proportion, or integration time.

As you can imagine, given all of the various factors involved, not all asphalt mixes will compact with equal ease. Perhaps the single largest factor is the physical dimensions of the aggregate utilized. Dense grade asphalt, which uses a mixture of small, medium, and large aggregate sizes, has a fairly predictable compaction behavior. More difficult to compact are open grade asphalts. These mixes leave out medium aggregate. This gives the resulting pavement a stiffer quality, but also increases the amount of force that must be used to compact it to an adequate degree.

Temperature

The most common type of asphalt where temperature is concerned are so-called hot mixes. Yet cold and warm mixes are increasingly being recognized for certain manufacturing and installation advantages. The temperature of a mix can affect the ease of compaction greatly. It is easy to understand why this is the case when discussing the temperature of the asphalt while it is being poured--hot asphalt will tend to flow more readily--yet manufacturing temperatures can also play a role in compactiblity.

Generally speaking, the higher the manufacturing temperature, the more easy an asphalt mix will be to compact. In other words, the worker in charge of operating the drum roller must know to exert a lighter pressure. Over-compaction can easily lead to the formation of cracks, ruts, and other structural deficiencies. Asphalt manufactured at low temperatures, on the other hand, will need a great amount of roller pressure in order to reach the ideal density, as determined by the engineer associated with the particular paving job.  


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