asfalto

Asfalto, or asphalt, is a viscid, black, sticky substance used primarily as a binder in road construction. It consists mostly of bitumen, a dense hydrocarbon material derived from crude oil, combined with graded aggregates such as crushed stone, gravel, sand, and filler. Natural deposits of asphalt also occur in some regions. In road pavements, asphalt concrete binds the aggregates with the asphalt binder to form a hard-wearing surface when laid and compacted.

Asphalt is produced by heating and blending asphalt binder with aggregates. Common forms include hot mix asphalt (HMA), which is laid hot; warm mix asphalt (WMA), prepared at lower temperatures with additives; and cold mix, which uses asphalt emulsions. Cut-back asphalts use solvents that vaporize after application, but their use has declined due to emissions. Reclaimed asphalt pavement (RAP) can be recycled into new asphalt mixes.

Major uses include road and highway surfaces, airport runways, parking areas, and waterproofing or roofing applications (asphalt shingles). Properties such as viscoelasticity, temperature susceptibility, and aging behavior influence performance. The binder improves cohesion and waterproofing, while aggregates provide stiffness and load distribution. Asphalt is sensitive to temperature: softens in heat and becomes brittle in cold, and aging through oxidation hardens the material.

Environmental aspects include energy use in production, emissions, and the benefits of recycling RAP. Asphalt is widely recycled, reducing resource use and waste. The history of asphalt goes back to natural deposits used in ancient times, with modern asphalt pavements developed in the 19th century in various regions.