Modern asphalt is composed if approximately 95% aggregates (stones, gravel, sand) and 5% asphalt/bitumen. Almost 90% of the asphalt produced in the United States is used for the construction of roads and surfaces. Although asphalt if very durable, repairs to roads do need to be made. The Federal Highway Administration estimates that 99% of repaired asphalt is later used for the construction of new roads. This means that even when asphalt does wear down, it almost never goes to waste!