Which of the following is NOT a way to increase compactive effort?

Decreasing the roller's diameter is not a method to increase compactive effort. In asphalt paving, the effectiveness of compaction is influenced by a combination of the roller's weight, the type of roller, and its operational parameters. A larger roller diameter allows for more stone-to-stone contact, increasing the surface area that can deliver compressive forces to the asphalt mix.

When considering factors that effectively enhance compaction, increasing the air pressure of the roller contributes to a harder impact on the asphalt, while increasing the weight of the roller directly affects the amount of force applied during compaction. Slowing down the paver can also aid compaction as it allows for more time for the asphalt to be compacted before it cools, thereby integrating compaction techniques more effectively.