For the first time, the development of prediction models of the penetration grade and the softening point of vacuum residues (VRs) and pavement asphalts, from the structural data obtained with proton nuclear magnetic resonance (1H NMR) and relaxometry data obtained via low-field nuclear magnetic resonance (LF NMR), is reported. The correlation between the structural data (1H NMR, percentage of different proton kinds), the relaxometry data (T 2, spin–spin relaxation time), and the properties, was measured with principal component regression (PCR). The best models were those obtained with PCR, which were validated via k-fold cross-validation, with k = 10. In particular for the VR, the best model for the penetration grade was obtained from LF NMR, with a training R 2 of 0.99 and a validation R 2 of 0.96; the best softening point was obtained from the combination of 1H NMR and LF NMR, with R 2 values of 0.99 and 0.87, respectively. For the asphalts, the best model for the penetration grade was also obtained from the combination of 1H NMR and LF NMR, with R 2 values of 0.99 and 0.94, respectively. Note that these prediction methods require less sample quantity, time, and personal effort than the ASTM standards.

This paper reports the findings of a one-year long study, that every week measured the physicochemical properties (P: penetration; A: softening; Ip: penetration index; V: rotational viscosity, R: mass loss), and the spectroscopic and the relaxometry properties via nuclear magnetic resonance, of the vacuum residues (VR) produced in a refinery and those modified into asphalts to fabricate pavements with penetration grade 60/70. The evolution of the structural changes, along the time of study, was measured via high-field and low-field 1H NMR and analyzed through multivariate statistical methods. The attained results with high-field 1H NMR showed that when the VR are oxidized, the proportion of protons associated with the high-molecular-weight polyaromatic increases. On the other hand, the low-field 1H NMR results, through a greater number of unimodal distribution plots of T 2 relaxation time, showed the homogenization of the aggregation as well as of the dynamic properties of the molecules, thus indicating that the aging of asphalts cannot be prevented despite the treatment. After analysis of the physicochemical properties, it was found that some refinery VR samples do not meet the quality specifications of penetration grade 60/70, dictated by the National Roads Institute of Colombia (INVIAS), to be employed as raw material in the manufacturing of pavements, but only after being processed and modified.