Comparison of the Superpave Gyratory and Proctor Compaction Methods for the Design of Roller-Compacted Concrete Pavements

Abstract

Roller-compacted concrete (RCC) is gaining popularity as a paving alternative for various roadway applications. RCC is a zero-slump concrete mixture that does not require forms, reinforcing, jointing, or finishing. This type of material combines the advantages of conventional concrete pavements with the ease of construction of an asphalt pavement and can be opened to traffic more quickly than conventional concrete pavements. The Superpave® gyratory compactor was investigated as an alternative to Proctor compaction (ASTM D1557) for the design of RCC paving mixtures. Seventeen mix designs that encompassed a range of aggregate sources, gradation types, and natural sand contents were generated. In general, the gyratory method did not produce designs equivalent to the Proctor method, in that the gyratory method resulted in higher densities and lower optimum moisture contents. Gyratory compaction tended to generate a maximum, or terminal, achievable moisture content, regardless of the amount of moisture mixed in the specimen. The corresponding densities continued to increase rather than display the parabolic relationship typical of Proctor compaction. The highest densities by both compaction methods tended to be achieved for blend gradations that most closely followed the maximum density line and included the greatest percentages of natural sand.