How are Asphalt Mixtures Is Made?
Asphalt Mixes (Mixing)
Like any good recipe, the ingredients should be high quality, they should be carefully measured, and they should be cooked at exactly the right temperatures. At the asphalt plant, the aggregates are precisely blended into a gradation and then dried and heated to the right temperature. The mixture is then completely coated with liquid asphalt cement. There are two types of asphalt plants, batch and drum. Drum mix plants dry the aggregate and blend it with asphalt in a continuous process in the same piece of equipment. With batch plants, the rocks are first dried and heated, then added to the pugmill and blended with the asphalt one batch at a time.
Transporting and Placing Asphalt Mixtures
Once mixed, the asphalt can be loaded into trucks and transported to the job site. It is then placed on your asphalt paving project using a paver. Once the paver lays the asphalt mix, it is compacted with rollers until it has just the right number of air voids, as determined in the mix design or recipe.
Hint: The temperatures are very important. The best temperatures for mixing, transporting, laying and compacting your asphalt pavement are determined based on how stiff (viscous) the asphalt is, how far and long it must be transported to your project site, and when it will be compacted. If it is compacted too hot, the air voids will be too low and the mat will “shove” and rut. If it is too cold, it will be difficult to compact and the air voids will be too high.