Rigid Pavement Repair and Maintenance Strategies for Roads & Highways
IntroductionThe United States is home to nearly 3.7 million kilometers of paved roads, and 94% of these roads are surfaced with asphalt materials. It is estimated that approximately 4,000 asphalt contractors are producing approximately 500 million tons of hot mix asphalt (HMA) valued at nearly 20 billion dollars each year. The demand on highways has increased many times. For instance, since 1970, the population of the United States has increased 34%, but licensed drivers by 68%, registered vehicles by 94%, and vehicle miles traveled by 143%. However, the highway departments, due to many factors (e.g., lack of funding, etc.), around the country have added only 6% of roads for these increases. In addition, each year approximately $13 billion is spent on highway construction and repairs. Moreover, the Federal Highway Administration (FHWA) estimates that the cost to bring our nation’s roads up to minimum engineering standards over the next 20 years will be over $550 billion.
Simultaneously, many municipalities are also facing a serious issue regarding scrap tire generation and disposal. A typical passenger-car tire weighs about 9.1 Kg and consists of 60% rubber, 20% steel, and 20% fiber and other by-products. The U.S. generates approximately 303 million scrap tires each year, which translates into a rate of one tire per person per year. Nearly all states have some form of scrap tire legislation or regulations on the books. Many states ban the landfilling of whole tires, and several states ban all scrap tires from landfills. In addition, many states charge a minimal scrap tire fee to consumers who are replacing old tires with new tires. These states apply funds collected in this manner towards the handling and disposal of scrap tires. Figure 1 shows the breakdown of the scrap tire distribution in USA.