Sylvester, Tony

Cold-recycling processes such as Cold in Place Recycling (CIR) and Cold-Central Plant Recycling (CCPR) offer opportunities for innovation through the use of recycling additives (RAs). The objective of this project was to evaluate the efficacy of rejuvenating asphalt emulsions in the CIR and/or CCPR process in terms of potential performance benefits relative to existing stabilization options. An experimental matrix was designed to include several of the mix design factors known or thought to control mix performance. Rejuvenating asphalt emulsions containing both Bio-based and petroleum-based RAs were produced and compared to a control engineered emulsion with a proven field history of performance. Inclusion of RAs did not negatively impact mixture stability or the mechanism of strength, while generally improving the CT Index of the tested cold recycled mixes compared to the use of a similarly graded control emulsion. The concept of utilizing a “Balanced Mix Design” approach was explored to quantify the performance attributes of these materials. Mixture stability at 40 °C and mixture IDEAL CT Index at 25 °C were ultimately selected as the performance tests used in the balanced mix design framework. To aid rapid implementation of the results, the recommendations were also written in the form of a specification amendment document, included in the appendix of this report.