Constructing and maintaining roads with this product is faster and not as disruptive as using concrete, which has a long curing time, according to the APA. Asphalt is generally considered to be cheaper and easier to maintain. When such a road needs to be replaced, it is only necessary to replace the top layer, while other types of roads may need to be removed and replaced completely. The product has a better ride Asphalt's smoothness results in not only a smoother ride, but enables roads to last longer because truck tires bouncing on bumpy roads wear out the roads more quickly. Smoother roads also reduce noise pollution and make pricey noise walls unnecessary. What the average motorist calls asphalt is technically asphalt concrete. This uses the product as a binder for construction aggregate, which consists of crushed stone, gravel, sand and other material. While this product has been in wide use since the 1920s, recent years have seen new advances in the mixes. Superpave, a performance-based design system, arose out of studies by the Transportation Research Board in the 1980s. Superpave served to modernize the industry to handle contemporary traffic loads. The Federal Highway Administration got involved in devising performance-based specifications for hot mix asphalt concrete (HMA), the type of product used most often on major highways. By 2003, 47 states made Superpave specifications a standard specification. Warm mix asphalt concrete (WMA), which uses cooler temperatures than HMA, can extend the paving season and make it more possible to do night paving, according to the Federal Highway Administration. It uses up less energy Constructing this type of pavement uses 20% less energy than constructing other types of pavement. It also reduces emissions and can be used in a wide variety of pavement thicknesses. It can even be used for asphalt basketball courts. The industry recycles or reuses about 95 tons of the product each year, making it the top recycler in the U.S., the APA says. The Federal Highway Administration promotes the use of Reclaimed Asphalt Pavement (RAP), also known as asphalt chunks, which is typically removed from existing roads during repairs. Other material such as rubber from old tires can also be recycled for use in the product.