Which factor is NOT categorized as affecting compaction?

The correct answer is that weather conditions are not categorized as affecting compaction in the context of roadway construction. Compaction is primarily influenced by physical and procedural factors rather than changes in weather.

Factors such as subgrade and bases directly impact how well a material can be compacted; a strong and stable subgrade provides a good foundation for compaction efforts. Similarly, the equipment used and the procedures followed during compaction are critical; different types of compaction equipment are designed for specific materials and conditions, and following proper procedures ensures optimal density and stability. Layer thickness is also significant because it determines how effectively each layer can be compacted—too thick may lead to inadequate compaction within the layer.

While weather conditions can have an indirect effect, such as soil moisture content affecting the compaction of certain materials, they are typically not classified as direct factors in the compaction process itself. Therefore, focusing on the equipment, procedures, layer thickness, and underlying structures provides a more direct understanding of compaction dynamics.