In this Caltrans News Flash, you’ll learn how concrete and asphalt pavements are made, how they are different and why the Department uses both.

Both asphalt and concrete are made from a rock or gravel base, but the material that binds the rock together is different. Cement holds concrete together, and in asphalt, refined oil binds the rock and gravel.

Before placing pavement, Caltrans studies the soil at the site, the traffic the roadway is expected to carry, and the weather to determine which material is best for each location. Concrete handles high-truck traffic, chains and studded tires better, so Caltrans uses it in cities and on mountain passes. Two thirds of California’s state highway system is asphalt, which cures faster and is less expensive.