Quantification of re-refined engine oil bottoms (REOB) in asphalt binder using ATR-FTIR spectroscopy associated with partial least squares (PLS) regression

Re-refined Engine Oil Bottoms (REOB) has been used in recycled asphalt materials for flexible pavements in recent decade, due to its effects on softening aged binder and relatively low cost. However, concerns on the pavement performance of those materials including REOB in asphalt binders have been reported and linked to the use of REOB. Consequently, methods for detecting and quantifying REOB in asphalt binders have seen increased interest to control the use of these recycled oils. This study is for the first time to introduce the use of the Partial Least Squares (PLS) regression in Attenuated Total Reflection-Flourier Transformed Infrared (ATR-FTIR) spectroscopy analysis of asphalt binders for determining REOB content. The PLS regression analysis gives the advantage of using the whole ATR-FTIR spectroscopy of REOB blends. The results show that an accurate prediction model can be derived by using the PLS regression analysis on the ATR-FTIR spectra of REOB blends.