Comparative Study on Recovered Binder Properties Using Three Asphalt Emulsion Recovery Methods

Determining the properties of residual binders is important to the effective use of asphalt emulsion chip seals. Yet, the effect of laboratory methods on recovered binder properties used to simulate residual binders in the field is not well understood. In this research, the residues of five asphalt emulsions were compared after recovery by three methods, a Hot Oven procedure (similar to ASTM D244-04), a Stirred-Can procedure (as reported in TXDOT 0-1710), and a Warm Oven method (ASTM D7497-09). The recovered binders were tested with size exclusion chromatography (SEC) to assess the presence of residual moisture. Properties of the original base binders and the corresponding recovered binders were compared using dynamic shear rheometry and Fourier transform infrared spectrometry. The SEC results showed no residual water in any of the recovered samples, except the samples from Warm Oven recovery, which showed a small detectable amount of residual moisture. The results from statistical analysis of binder properties using ANOVA plus Tukey's Honestly Significant Difference test suggest that recovered binders from the Warm Oven method are statistically different from their base binders. Nevertheless, considering each of the residues recovered from the three methods in paired comparisons with the other residues, none is statistically different from the others.