Determination of physico-chemical parameters for bitumens using near infrared spectroscopy

Bitumens are usually characterised by using time-consuming empirical or functional physicochemical tests. This paper reports a method for the determination of various physico-chemical properties (viz. viscosity at 60 and 135°C, density at 15°C, softening point and Fraass breaking point) and the chemical composition (viz. n-heptane-insoluble asphaltenes, asphaltenes+insoluble polar resins (IPR), saturated hydrocarbons, aromatic hydrocarbons and resins) of bitumens using near infrared (NIR) spectroscopy in conjunction with partial leastsquares regression (PLSR). The proposed method surpasses existing alternatives in expeditiousness; also, it allows the simultaneous determination of several parameters from a single spectrum and is amenable to implementation in the continuous mode. Its accuracy and precision are essentially identical with those of reference methods; the relative standard deviation ranges from 0.2% for density to 14% for the Fraass breaking point.