Compaction of Graded Aggregate Bases and Subbases

Compaction of unbound, granular base and subbase layers in flexible pavement systems is reviewed. The distinction between density and compaction is related. The beneficial effect of increased density achieved through compaction on specific properties of graded aggregate mixtures, including strength and deformation characteristics, is demonstrated by the use of data drawn from the literature. The influence of: (1)Aggregate gradation; (2)water content; and (3)excessive fines for a given compactive effort on achievable density, and ultimately on the performance of the pavement system, is analyzed. In-service compaction of granular base materials by traffic is reviewed. Recommendations for specification requirements for granular base and subbase materials to be used in pavement systems that will be subjected to the demands of modern, high-volume, high-speed, heavy traffic, are made.