Exploiting Synergistic Effects of Intermolecular Interactions To Synthesize Hybrid Rejuvenators To Revitalize Aged Asphalt

Abstract

This paper examines the merits of using a hybrid bio-oil derived from algae and swine manure to rejuvenate aged bitumen by restoring the bitumen properties which are degraded during oxidative aging. Nitrogencontaining compounds have been found to be effective for decreasing the size of molecular agglomerates which are intensified during aging provided they adequately penetrate into the oxidized asphaltene agglomerations. The enhancement effect is mainly attributed to their electronic structures, including the polar head and hydrocarbon tail which can interact with asphaltene with CH−π interactions. In this study, we hypothesize that combining bio-oils extracted from high-protein algae and swine manure can help balance the heteromolecule content, which in turn leads to synthesizing an effective hybrid biorejuvenator to revitalize aged bitumen. Computational analysis was used to determine the specific rejuvenation mechanisms between the hybrid biorejuvenator and an oxidized asphaltene dimer found in the aged bitumen. Our analysis via density functional theory showed that the biorejuvenation process involves a two-step mechanism: First, the biorejuvenators interact with polar sites of the asphaltene nanoaggregates in aged bitumen to increase intersheet spacing referred to as the lock-and-key mechanism. Second, the biorejuvenators intercalate into the intersheet spacing within the stacks of asphaltene to induce deagglomeration. Accordingly, the hybrid biorejuvenator was designed to have molecules targeting either of the two mechanisms. Therefore, blending molecules of the algae-based bio-oil, which are mainly effective in the first step with those of swine-manure-based bio-oil, which are effective in the second step led to a biorejuvenator with significantly higher efficiency than either of them individually. This was attributed to heteroaromatic motifs and nitrogencarrying compounds with a hydrocarbon tail, which contribute to opening (lock-and-key) and intercalation mechanisms, respectively. The enhanced efficiency of the hybrid biorejuvenator was further verified via a series of laboratory experiments as well as molecular dynamics simulations; it was found that the hybrid biorejuvenator is more effective to increase crossover modulus and decrease size of asphaltene nanoaggregates of aged bitumen than the swine-manure-based bio-oil and the algaebased bio-oil alone. Regardless of the bitumen origin, the hybrid biorejuvenator was able to promote deagglomeration of oxidized asphaltene and revitalize aged bitumen.

Towards an understanding of diffusion mechanism of bio-rejuvenators in aged asphalt binder through molecular dynamics simulation

“…Based on gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) data analyses, bio-rejuvenator contained a large number of amide and nitrogenous functional groups (Fini et al, 2011;Xiu et al, 2012). Pahlavan et al, 2018Pahlavan et al, , 2019 proposed the molecular structures (Number: BR-1~BR-7) of the main components in bio-rejuvenator. In terms of molecular structure form, these bio-rejuvenator molecules can be divided into straight chains and aromatic compounds.…”

“…It has been demonstrated that amide and nitrogenous molecules are the key components of bio-rejuvenators to exert regenerative effects. The chemical structures of the two active ingredients have been constructed by Farideh Pahlavan et al (2019) and Masoumeh Mousavi et al (2016). Based on MD simulations, Mullins (2010), Li et al (Li andGreenfield, 2014), andGreenfield (2011) have carried out extensive research on the microstructure, component characterization, and simulation treatment of petroleum asphalt binder, providing a methodological basis for the bio-rejuvenator's modified aged asphalt binder.…”

“…Based on MD simulations, Mullins (2010), Li et al (Li andGreenfield, 2014), andGreenfield (2011) have carried out extensive research on the microstructure, component characterization, and simulation treatment of petroleum asphalt binder, providing a methodological basis for the bio-rejuvenator's modified aged asphalt binder. In two studies, Pahlavan et al, 2018Pahlavan et al, , 2019 analyzed bio-rejuvenators' action mechanism in aged asphalt binder based on density functional theory. During the recovery process, bio-rejuvenators are bound to the polar sites of the asphaltene nanoaggregates first (which was called "Lock-and-Key").…”

A Review on the Durability of Recycled Asphalt Mixtures Embraced with Rejuvenators

“…The hybrid rejuvenator showed high resistance towards ageing and moisture damage, whilst concurrently efficient in restoring the rheological properties in aged asphalt. Pahlavan et al [91] assessed the merits of using a hybrid bio-oil rejuvenator derived from algae and swine manure to rejuvenate aged asphalt by restoring the properties of the sample. The proposed rejuvenator indicated more noticeable restoration, along with better de-agglomeration of oxidised asphaltenes.…”

Analysis of different reclaimed asphalt pavements to assess the potentiality of RILEM cohesion test

“…During its service life, AC ages as a consequence of the traffic and environmental conditions, determining physico-chemical changes in the bitumen [3]. On the one side, bitumen is subjected to oxidation, i.e.…”