There's More to Paving Than Sidewalks

3 Common Types Of Hot Mix Asphalt

Hot mix asphalt is the formal name given to the most common type of asphalt used for paving today. As its name would imply, its primary distinction is that it is kept at a high temperature right up to the moment of its application--a temperature of roughly 300 degrees Fahrenheit. Hot mix asphalt is also frequently referred to as HMA, hot mix, blacktop, asphalt concrete, or simply asphalt. This article will introduce you to three different varieties of hot mix asphalt.

Dense Graded Mix

The two most important ingredients in asphalt are the asphalt binder, which acts as a sort of glue for the pavement, and mineral aggregate. Essentially, mineral aggregate is crushed stone, often gravel. The three types of asphalt discussed here all differ in terms of the size of the stones that make up their aggregate.

In dense graded mixes, a range of aggregate sizes is used, from very fine to the coarsest chunks. These different sizes are incorporated in equal amounts. When compacted well, this means that the aggregate particles are capable of interlocking well, forming a relatively impermeable surface. Dense graded mix also has the advantage of being one of the least expensive mixes.

Stone Matrix Asphalt

Stone matrix asphalt is a so-called gap-grated hot mix. That means that, unlike dense graded mix, there is a conspicuous absence of medium sized aggregate particles. The result is an asphalt with a greater degree of contact between large sized aggregate. This increases the stiffness and durability of the asphalt, making it more impervious to developing ruts as time goes on.

Stone matrix asphalts tend to be more expensive than dense graded mixes. That's because the aggregate used must meet certain standards of hardness in order to successfully withstand the pressure of direct contact. For this reason, stone matrix asphalt is generally used only on high traffic roads and highways where an increase in rut resistance is vital.

Open Graded Mix

Open graded mix is distinguished from both of the varieties discussed above in that it is specifically designed so as to be permeable to water. This is accomplished by drastically reducing the amount of fine aggregate used. By reducing the amount of standing water on a roadway, open graded mixes improve safety in three key ways.

First, they decrease the amount of tire splash thrown up by vehicles, thus leading to an improvement of visibility in wet conditions. Second, they reduce the risk of hydroplaning caused by sheets of water on the roadway. Finally, they improve a vehicle's skid resistance. These qualities make open graded mix an attractive choice for roads in parts of the country with a increased amounts of precipitation.

For more information, contact Construction Asphalt Paving Services Inc or a similar company.