Fused Aromatics To Restore Molecular Packing of Aged Bituminous Materials

Abstract

This study incorporates computational and laboratory experiments to determine specific interaction mechanisms between conjugated structures (interrupted and continuous conjugates) and selected polyaromatics hydrocarbons (PAH) stacks such as those found in oxidized asphaltene molecules. The theoretical results obtained by quantum-mechanical calculations and molecular dynamics simulations show that both continuous and interrupted conjugates are effective to weaken the π-intersheet forces and decrease the size of PAH nanoaggregates, with interrupted conjugates being more efficient than continuous conjugates to exfoliate PAH stacks. Owing to their limited partial entrance into the PAH stacks, interrupted conjugates are not trapped inside the PAH interlayer, and can easily detach from the stacks. This allows an interrupted conjugate not to be consumed in interaction with one PAH stack, making the interrupted conjugate available to affect many other stacks in the matrix. The higher exfoliation capacity of the interrupted aromatic conjugates is also evidenced in the results of our experiments based on UV−vis and rheometry analyses. This is reflected in a higher reduction in the polydispersity index and a higher increase in both the crossover frequency and crossover modulus of aged bitumen (containing stacks of large PAH referred to as asphaltene nanoaggregates) when it is doped with an interrupted conjugate (fluoranthene) compared to when it is doped with a continuous conjugate (pyrene). The study results contribute to the body of knowledge by providing an in-depth understanding of how variation in the π-electron distribution of conjugated structures affects their efficacy to exfoliated self-assembled stacked structures of polyaromatic hydrocarbons such as asphaltenes.

Balancing the Aromatic and Ketone Content of Bio-oils as Rejuvenators to Enhance Their Efficacy in Restoring Properties of Aged Bitumen

“…The observed improvements could be attributed to the CPWR bio-oil's having a significant content of aromatics and ketones compared to the PW bio-oil. According to Pahlavan et al, 35 the presence of a combination of ketones and aromatics is required to enhance the efficiency of a rejuvenator. Because of the presence of aromatics in the CPWR bio-oil, the oxidized asphaltenes will undergo depolymerization reactions.…”

“…The addition of waste tire rubber can result in an optimal H/C eff which can generate olefins and further suppress the formation of unexpected polyaromatic hydrocarbons . The high aromatic content in bio-oil can also make it a good candidate for the rejuvenation of the aged bitumen found in asphalt pavements after their service life . On the other hand, the chemical compounds from lignin pyrolysis are polyphenylpropanoid macromolecules with aromatic monomers, which facilitate the interaction between lignin-derived compounds with asphaltene …”

“…Aging in asphalt pavements leads to the loss of volatiles and light molecular components in bitumen, which is the glue holding the stones together in asphalt pavements . Aging further promotes physicochemical changes in bitumen that make it brittle and prone to cracking. , Aging in asphalt pavements is promoted by their exposure to ultraviolet, light, moisture, and oxidation during their service life . Hence, to recycle aged bitumen and use it in new-pavement construction, there is a need to rejuvenate its properties to restore the performance characteristics.…”

“…34 The high aromatic content in bio-oil can also make it a good candidate for the rejuvenation of the aged bitumen found in asphalt pavements after their service life. 35 On the other hand, the chemical compounds from lignin pyrolysis are polyphenylpropanoid macromolecules with aromatic monomers, which facilitate the interaction between lignin-derived compounds with asphaltene. 14 Aging in asphalt pavements leads to the loss of volatiles and light molecular components in bitumen, which is the glue holding the stones together in asphalt pavements.…”

Investigation of Balanced Feedstocks of Lipids and Proteins To Synthesize Highly Effective Rejuvenators for Oxidized Asphalt

“…The crossover frequency is the point where the loss modulus and the elastic modulus are equal; it is known as a fundamental property of bitumen. It has been used as an indicator to track the extent of aging and rejuvenation. ,, …”