Prediction of the Penetration Grade and Softening Point of Vacuum Residues and Asphalts by Nuclear Magnetic Resonance and Chemometric Methods

Abstract

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.

Characterization of Asphalt Aging by Analytical Techniques: A Review on Progress and Perspectives

“…29 According to the authors, by photooxidation mechanisms, nonpolar species tend to polymerize from the oxidation of these compounds in carbonyl groups, which can interact. This behavior was observed from the variation of DBE values by 133 LF-NMR and 1 H NMR estimation of the viscosity of natural and aged samples based on T 2 measurements and relative hydrogen index Sun et al 134 1 H NMR correlation of the types of molecules with self-healing ability in asphalt Wang et al 18 LF-NMR measurements of the pore structure of petroleum asphalt cement mortar Menapace et al 19 LF-NMR variation in viscosity measurements of asphalt aged over the long-term by T 2 measurements Jaimes et al 20 LF-NMR and 1 H NMR measurement of physicochemical properties such as penetration, softening, rotational viscosity, and mass loss by NMR associated with chemometrics Blumich et al 23 NMR-MOUSE evaluation of the durability of rubber-modified asphalt Jaimes et al 135 LF-NMR and 1 H NMR prediction of the degree of penetration and softening point of vacuum residue by NMR associated with chemometrics Porto et al 7 13 C NMR characterization of organic sulfides present in A.C. Mansour et al 136 1 H NMR use of bitumen antioxidants to reduce the effects of aging Caputo et al 137 FT-NMR-SDC investigation of microchanges that occur in bitumen aging Lushinga et al 138 carbon number and the evaluation of the classes present, which revealed that oxygenated classes increased significantly.…”

Correlation and modelling of the penetration and softening point tests of bitumen binders with a variety of physical and chemical properties

“…The models developed by Jaimes et al [10] involved the use of either LF-NMR alone or in combination with H-NMR data for the prediction of SP or PEN. The T2 relaxation time distribution measured by LF-NMR can indirectly reflect the composition of the bitumen samples through the impact of each component of the bitumen samples on the general molecular dynamics [10]. However, these proposed models were built using samples produced by one refinery and they belong to the same penetration grade.…”

“…The most common way is to separate bitumen into four fractions called SARA fractions: saturates, aromatics, resins, and asphaltenes, which exhibit an increase in aromaticity, polarity, viscosity, and average molecular weight as we move from saturates to asphaltenes [2,3,5]. Other analytical techniques like Fourier Transform Infrared (FT-IR) spectroscopy, Nuclear Magnetic Resonance (NMR), or mass spectroscopy can help to provide relevant information about the average chemical composition of bitumen [6,[10][11][12][13]. Besides, techniques like Gel-Permeation Chromatography (GPC), also called Size Exclusion Chromatography or SEC, Atomic Force Microscopy (AFM), Thermogravimetric Analysis (TGA), Differential Scanning Calorimeter (DSC) and Simulated Distillation (SD) by High-Temperature Gas Chromatography (HTGC) and low-field NMR can give more insights into the molecular dynamics that affect physical properties of bitumen [6,9,10,14,15].…”

“…A more recent trend is the use of spectroscopic techniques to model SP and PEN, like Fourier Transform Infrared Spectroscopy (FT-IR) and Nuclear Magnetic Resonance (NMR). Jaimes et al proposed some models for SP and PEN predictions based on Low Field NMR (LF-NMR) and H-NMR [10]. However, most of the proposed predictive models of SP or PEN were built by using samples with narrow ranges of SP and PEN, and the predicted results are relatively unreliable compared to the standard methods.…”