Major streets and highways are made of cement or asphalt cement. Cement highways last longer and can handle lots of traffics. The downside – it takes a long time for cement roadways to cure and they are expensive. When a roadway is new, as in, it has yet to be used by the public, cement is an excellent way to go, particularly for a super highway that will see a large volume of traffic.
But, if the roadway is used daily and handles lots of traffic, to have it shut down for repair that involves waiting for cement to dry can cause hardship on those who use the roadway since they will have to find alternate routes to their destination. In addition, businesses located along the cement roadway could be financial impacted by repairs. Because of the negative aspects of cement roadways, many are now built and repaired using asphalt concrete, which is also less costly than cement alone. There are several different types of asphalt concrete. First, we need to understand the terminology.
“Asphalt” is the term given to the binder; that’s what thickens and holds the material together. Asphalt looks brownish-black and most likely comes from an oil-based by product. Concrete can be made from sand and rock fragments. The components of concrete are called aggregate.
Basic Definition Of Some Types Of Asphalt Concrete:
Cold Mix. The asphalt is mixed with water before adding and mixing the concrete ingredients. This type of asphalt would be used to patch holes or to surface less frequently used roads.
Hot Mix. The asphalt is heated to thin it before it is added to dried aggregate. The combination is laid and compacted while it’s about 300 degree Fahrenheit. Hot mix is the most common form of asphalt concrete.
Warm Mix. Is the same as hot mix, only not as hot. With the environment in mind, warm mix is valued for reduced fuel needed in the production process. From a paving standpoint, warm mix is easier to compact and then there is the obvious advantage for the workers not having to work with the heat generated from hot mix.
Recyclable
Most people are not aware that asphalt can be recycled. When all or parts of a roadway are removed, the material can be crushed and reused as a part of hot mix.
Asphalt concrete that is removed from a pavement is usually stockpiled for later use as a base course material. This reclaimed material, commonly known by the acronym ‘RAP’ for recycled or reclaimed asphalt pavement, is crushed to a consistent gradation and added to the HMA mixing process.
Did You Know …
Gas stations often have two kinds of pavement on the lot. It is better to use cement, rather than asphalt, in the area around gas and kerosene pumps. The reason for this is gasoline and kerosene will dissolve the binding agent in a petroleum based pavement (i.e., asphalt). But, cement is usually more expensive than black top. That is one of the reasons only the area near the pumps is cement.
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RESOURCES
www.thefreedictionary.com
www.wikepedia.com
www.warmmixasphalt.com
www.hotmix.org/
