For the tenth year in a row Asphalt pavement is the most recycled material in America! Nearly 100 million tons of Recycled Asphalt Pavement (RAP) is re-used in the U.S. every year. RAP has been used widely for more than 30 years and now makes up about 12 percent of the volume of the asphalt mixtures produced in the U.S.
Asphalt pavements are also the most recycled material in the rest of the world.
What’s our secret?
Asphalt pavements are comprised of layers or “lifts” of asphalt concrete, a combination of graded aggregate and sand, typically 94 to 96 percent, bound together by asphalt cement (better known as asphalt binder). Asphalt cement/binder is a most unique material; a solid “glue” or cement at room temperature, it becomes an oil-like lubricant when heated allowing the asphalt paving industry to coat aggregate particles while they are hot, then place and compact into pavement layers before it cools and glues all the particles together.
Here’s what separates asphalt from all the rest
Unlike Portland cement which chemically changes when mixes with water (think of two-part epoxy), asphalt cement/binder’s properties change from solid to liquid to solid again as a function of temperature. This is a physical change in properties, no chemical change takes place. Therefore, asphalt pavements and mixes can be removed at the end of their long service lives, reprocessed, heated again and turned back into new asphalt pavement.
100 percent of the aggregate and asphalt binder is recovered and reused as aggregate and asphalt binder!
Old asphalt pavements and mixes are not the only materials that can be recycled in to asphalt mixes. Asphalt shingles, whether manufacturers’ waste or post-consumer shingles from asphalt shingle roof that been removed are high in asphalt cement/binder content. Shingles are easily processed and, like with recycling old asphalt mixes, the asphalt cement/binder is 100% recovered and reused in new asphalt concrete mixes.
Asphalt pavements can also be recycled by cold process, either in-place or by cold central plant recycling. As with hot mix recycling, ALL asphalt cement/binder and aggregates are fully recovered and recycled back into new asphalt pavement layers.
Other materials besides old asphalt pavements and roofing shingles are also recycled into asphalt concrete. These include ground tire rubber as a substitute for expensive polymers; crushed, processed post-consumer glass as a fine aggregate substitute; and even crushed Portland cement concrete. Now that’s true recycling!
These are not:
Despite their claim of “100% recyclable”, Concrete’s only recycling value is as a poor quality aggregate. In fact, crushed concrete cannot be used in new Portland cement concrete! And, unlike asphalt cement/binder where 100% is recoverable AS ASPHALT CEMENT/BINDER, every cubic yard of concrete must have all new Portland cement!
Click below on one or all of the following topics to learn more of the technical details regarding recycling and asphalt mixes.
The 1973 Arab Oil Embargo saw the price of crude oil rise from less than $10 a barrel to more than $35 by 1981. Suddenly binder costs, only 5% of the total mix, were now 68% of the mix materials costs. This dramatic price increase, the aging of the U.S. highway system and the realization […]
Ten (10) million tons of post-consumer waste shingles or “tear-off” shingles from replacing old roofs are generated in the U.S. every year. Another one (1) million tons of manufacturers’ waste shingles are also generated. Known as Recycled Asphalt Shingles (RAS) they are an excellent source of asphalt binder, containing 15-35%, and can be processed, reheated […]
Sixty percent of the rubber consumed in the United States today is used to make tires. In 2008, 290 million new tires were shipped for use by cars and trucks. Of these, 80 percent were for passenger cars and 20 percent were for trucks. In addition, 20 percent were “original equipment” tires and 80 percent […]
Pavement Recycling is a technique where an existing degraded pavement is modified and transformed into a homogeneous structure that can support the traffic requirements. Materials from the existing pavement are reused in the construction of a new layer and can result in considerable savings of material, money, and energy. Because of the reuse of existing […]