Increased Single-Lift Thicknesses For Unbound Aggregate Base Courses

International Center for Aggregates Research
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International Center for Aggregates Research

"State departments of transportation (DOTs) have used aggregate base courses for many years as an integral structural component of pavements. Specifications prescribe requirements for placement and compaction of aggregate bases in addition to quality requirements for the aggregates. Typically, specifications also limit the lift thickness of unbound aggregate bases. While advances have been made with regard to the capabilities of compaction equipment, lift thickness limits have generally remained unchanged, and this has raised the question of whether these specifications are too restrictive... The objective of this study was to evaluate the feasibility of compacting unbound aggregate base courses in thicker lifts than currently permitted by DOTs and to identify effective test methods that assess the quality of the final compacted base or subbase."