Recovery Method Comparison Andrew Hanz & Codrin Daranga Emulsion Task Force The Center, Heritage Research Group, Indianapolis, IN June 12, 2019

Motivation Previous results presented by Asphalt Institute showed high variability between labs for many of the tests select. Evaluate the low temperature evaporation recovery method Two labs and three machines: Ergon ran on two machines, MTE on one. Three different manufacturers. Effect of nominal draw down film thickness: 20 mil vs. 30 mil. Evaluate alternate recovery methods. LTE (PP-78) vs. Vacuum Recovery (ASTM D7944)

Work Plan Factor Description Low Temperature Recovery Method Evaporation (PP-78) Vacuum (ASTM D7944) Film Thickness 20 mils 30 mils Lab MTE Ergon Emulsions CRS-2 CRS-2L CRS-2P Responses: SPG Continuous Grade, G*/sinδ at grade temp., phase angle at grade temp.

Results – CRS-2 Continuous Grade Low Temperature Evap: Avg: 60.7, Std. Dev = 2.1 Vacuum Recovery: Avg: 60.4, Std. Dev = 0.8

Results – CRS-2L Continuous Grade Low Temperature Evap: Avg: 65.1, Std. Dev = 1.25 Vacuum Recovery: Avg: 64.7, Std. Dev = 1.30 Lab Bias: MTE was higher

Results – CRS-2P Continuous Grade Low Temperature Evap: Avg: 69.8, Std. Dev = 1.7 Vacuum Recovery: Avg: 69.5, Std. Dev = 0.34

Results – Effect of Lab

Results – Effect of Recovery Method

Results – Effect of Film Thickness

Observations Effect of Lab Effect of Recovery Method Bias was shown for one sample CRS-2L. Other samples were equivalent. Effect of Recovery Method Same result for both labs across all three emulsions. Vacuum recovery method was less sensitive to variations in procedure (i.e. film thickness) for CRS-2 and CRS-2P.

Next Steps SPG and EPG from NCHRP 9-50 has established DSR based methods for evaluating emulsion residues. Apply these concepts to developing precision and bias of recovery methods. Needs Ruggedness of individual test procedures. Single lab and multi-laboratory precision. Will be critical to NCHRP 9-63 work.