Throughout Gauteng, many highway authorities make extensive use of the Tar and Chip process. This method involves the application of a hot bituminous emulsion onto an existing asphalt or concrete surface using specialist spraying equipment. Once the emulsion has been applied, clean, hard aggregate is spread over it. The combination of binder and stone is then rolled and subjected to traffic, which helps embed the chippings and form a durable surface layer. This layer protects the underlying pavement from wear and water penetration. A variety of aggregate types are available to achieve different aesthetic effects.