Estimation of RAP's binder viscosity using GPC without binder recovery

The binder viscosity in a reclaimed asphalt pavement (RAP) is usually measured from the recovered binder. To recover the aged binder from RAP, there must be a series of laboratory process which takes at least a day or two. This study was initiated to determine the possibility of estimating absolute viscosity of aged binder (in RAP) within a short time (2 h) by using gel-permeation chromatograph (GPC) technique. Many studies have shown that the GPC profile has a good correlation with physical properties of binder. To apply this concept, GPC tests were run on the samples from RAP mixtures without recovery. Statistical analysis indicated that absolute viscosity of the binder in an asphalt mixture could be reasonably estimated from the GPC test. The R-2 value of the absolute viscosity with large molecular size was as high as 0.95 for unmodified asphalt and 0.9 for polymer-modified asphalt binder.