Intelligent Compaction for Subgrades and Structural Layers AASHTO RAC High Value Research Workshop July 27, 2011

Intelligent Compaction for Subgrades and Structural Layers Overview Intelligent compaction is a promising construction technique under evaluation by several states Vibratory rollers are equipped to measure position, speed and drum vibration Data are processed and displayed in real time as a color-coded map of stiffness

Intelligent Compaction for Subgrades and Structural Layers Goals and methods Evaluate IC on highway projects for bound and unbound layers –Low- and high-plastic clay subgrades –Silty sand subbases –Crushed aggregate and recycled asphalt base courses –Asphalt overlays Determine accuracy of IC measurements through a variety of field tests

Intelligent Compaction for Subgrades and Structural Layers Findings Results were promising For unbound materials, IC is effective to map stiffness and identify weak areas prior to placement of new layers IC helps determine best rolling patterns for unbound layers and avoid over-rolling But challenges remain IC is not used for hot-mix asphalt finishing rollers yet Stiffness readings are influenced by supporting layers; adjustment factors or other field controls are needed Output values from different manufacturers’ equipment need to become more uniform

Intelligent Compaction for Subgrades and Structural Layers Outlook With further research, IC has the potential to lower construction costs, improve the uniformity of compaction, and increase pavement performance and service life.

Intelligent Compaction for Subgrades and Structural Layers For more information Wisconsin Highway Research Program project , Evaluation of Intelligent Compaction Technology for Densification of Roadway Subgrades and Structural Layers geotechnics/geotechnics_ htmlhttp:// geotechnics/geotechnics_ html Daniel Yeh (608)