This project proposes to develop and test a "smart pad" for pad foot roller compactors, which is very different from vibratory compaction systems. This project will integrate static soil stiffness measurement capabilities with wireless communications and the global positioning system for continuous real-time feedback on soil stiffness for fine-grained and mixed soil types.
Improve construction practices through new technology.
Measurement of soil stiffness during compaction of foundations for highway structures is critical to ensuring that design-life specifications are met. In this study, investigators developed a conceptual framework for determining pad?soil contact force and displacement (and, thus, soil stiffness) from sensors built into the pads and roller, constructed a prototype measurement system, and devised a wireless data acquisition system to enable fieldscale testing. The researchers successfully measured plastic and elastic soil deformation during compaction using laser-based distance sensors and pad-strain?based techniques. Laboratory and field testing confirmed the predicted strain field changes. Some elements of the model need further refinement to ensure repeatable and accurate measurement across various soil conditions.