Hot In-Place Recycling

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Environmental and Functional Benefits and Trade-Offs of Hot In-Place Recycling Treatment Techniques


Punit Singhvi, Hasan Ozer and Imad L. Al-Qadi


This report evaluated three test sites, located in Galesburg and Machesney Park, Illinois, and Dyer, Indiana, that were HIR treated and evaluated in-situ and in the lab. Physical and rheological properties of binder recovered from each site were obtained. Interaction plots, combining rut depth from the wheel track test (WTT) and flexibility index (FI) from the Illinois Flexibility Index Test (I-FIT), were in agreement with binder test results. Falling weight deflectometer and roughness measurements were conducted before and after HIR. The environmental assessment showed a difference in energy usage and GHGs of 3.9–17.6% and 1.3–19.2%, respectively, between a HIR process with 38 mm AC overlay and a corresponding traditional 50 mm mill and AC OL for different plant locations. Energy savings from using HIR treatments heavily depend on the surface treatment after HIR, thickness of overlay (if overlay is chosen as the surface treatment), and hauling distances for plant-produced materials needed for overlays. 


Report No. ICT-17-001, University of Illinois Center for Highway Pavement Preservation, December, 2016.