Field and Laboratory Properties of Roller-Compacted Concrete Pavements

Abstract

Roller-compacted concrete (RCC) pavements present three primary challenges relative to conventional concrete pavement: mixture design, structural design details, and construction process and verification. An investigation was initiated to reconcile the discrepancy between the field and laboratory properties of RCC pavements because of differences in laboratory mixture design procedures and field construction processes. Four RCC pavement projects in Illinois were selected for field coring along with sampling of RCC constituent materials for replication of the laboratory mixture design. Density measurements of field cores indicated that density decreased with depth into the pavement structure and the relative density at paving-lane joints could be as low as 80%. Statistical differences in compressive strength and fracture properties between field and laboratory samples were observed and result from differences in density. A 4% difference in density between field and laboratory samples resulted in an approximate 45% difference in compressive strength. The reduction in field RCC strength and fracture properties relative to the values obtained in the laboratory will result in decreased slab flexural capacity and field performance. Application of the gyratory compactor demonstrated that it can be used repeatedly to compact most RCC mixtures to similar target densities as the modified Proctor method and field-extracted cores. The gap between field and laboratory properties of RCC can be reduced by application of high-density pavers; improvement in mixture design procedure with the gyratory compaction method; a foundation layer beneath the RCC that is stiffer, thicker, or both; reduced RCC lift thicknesses to achieve specified density; or all of these.