A mixture with a brown, dull appearance is mainly indicative of what?

A brown, dull appearance in a mixture typically indicates the presence of an excessive amount of asphalt binder. When the quantity of asphalt is high, it can lead to an over-saturation of the aggregate, resulting in a shiny, less visually appealing surface. A proper balance in the asphalt binder content is crucial to ensure that the asphalt mix achieves the desired performance characteristics.

In contrast, the correct level of asphalt binder would generally create a mixture that has a more uniform, slightly glossy appearance. A mixture with too little asphalt binder would appear dry and crumbly rather than dull or overly shiny, and a well-mixed aggregate would not contribute to a brown, dull look but rather ensure uniformity and strength. High air void content usually results in a mixture that is not compacted properly, which often leads to a different set of visual defects, not specifically a dull brown appearance.