Asphalt

Asphalt (known in the industry as Hot Mix Asphalt, or HMA), is a combination of aggregates (usually crushed stone and some sand), filler (cement, hydrated lime or stone dust) and a bituminous binder called "asphalt cement". Additives are sometimes used (e.g. rubber from old car tires) . Reclaimed "asphalt" from old roads, called RAP (recycled asphalt pavement), is also, increasingly, being used.

When hot, HMA is pliable and can be rolled flat to create a smooth, durable, water proof substrate.