Study of Vacuum Residues and Their Transformation to Asphalts for the Pavement Industry by Nuclear Magnetic Resonance and Chemometric Methods

Abstract

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.

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.…”

“…Study at the molecular level of the aging asphalt is performed by different analytical techniques. Infrared (IR) spectroscopy provides information related to the functional groups present in the molecules that compose the asphalt and is widely used to determine carbonyl indexes and sulfoxide formation. − Nuclear magnetic resonance (NMR) spectrometry comprises information on the types of hydrogen and carbon, having a wide variety of methods for different applications; though compared to IR, it is still little applied. − …”