Optimizing Cold In-Place Recycling (CIR) Applications Through Fracture Energy Performance Testing

Status:  Complete
Report Date:  06/27/2016


Cold In-place Recycling (CIR) is pulverizing and rebinding existing Hot Mix Asphalt (HMA) pavements with bituminous and/or chemical additives without heating to produce a restored pavement layer. This process has become a desired rehabilitation alternative for cost, environmental, and performance advantages compared to standard practices. The process utilizes a train of equipment with either volumetric or weight control. It also utilizes various stabilization materials including emulsion, cement, combinations of emulsion/cement, and foamed asphalt. Performance-based laboratory tests to capture fracture energy of materials have shown they can correlate to field performance quite well. These tests offer an excellent opportunity to differentiate between processes and materials used in CIR for characterization and development of a performance-based specification. In this study, the performance of CIR using four different stabilization (rebinding) materials of Engineering Emulsion, High Float Emulsion (HFMS-2s), Commodity Emulsion (CSS-1) with Cement, and Foamed asphalt are compared using a newly developed testing method called Fracture Index Value for Energy (FIVE). This test is performed on notched Semi-Circular Bending (SCB) specimens by controlling the crack mouth opening displacement (CMOD) rate. The FIVE test is found to be a practical easy to perform test that is able to compare CIR material low temperature characteristics. In this study, the FIVE test first was verified against Disc-shaped Compact Tension (DCT) test results and then was applied on the four study mixtures. Furthermore, the FIVE test results went through a validation process with inter-lab comparisons by three different testing labs of Braun Intertec, American Testing Engineering, and the Minnesota Department of Transportation (MnDOT).

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