History and Future Challenges of Gyratory Compaction: 1939 to 2001

History is a dynamic tapestry of facts and perceptions, dates and personalities. This work attempts to capture the events and rationale of those who contributed significantly to the use of gyratory compaction in the design and field management of hot-mix asphalt and discusses the challenges ahead. Throughout the evolution of asphalt mix design several different types of laboratory compaction devices have been developed. In general, the goal of these laboratory devices is to fabricate a specimen for volumetric or physical characterization, or both. Depending on the system, specimens can be cylindrical, trapezoidal, or rectangular and compaction can be achieved through impact, kneading, or vibration. Gyratory compaction applies a kneading effort to fabricate cylindrical specimens. The evolution of gyratory compaction has resulted in several unique devices and a variety of methods.