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This paper examines the merits of using an inherently functionalized carbon, referred to as biochar as a free radical scavenger. The biochar was made from thermochemical liquefaction of a blend of algae (rich in protein and nucleic acids) and manure (rich in lipid). Here, we studied biochar’s efficacy as a free-radical scavenger and ultraviolet blocker to qualify it as an anti-aging additive in construction, including roofing shingles made from the bituminous composite. The study’s results show that the addition of biochar to bitumen significantly reduced the aging of bitumen. All tested biochars made from various relative proportions of algae and swine manure were found to be effective at reducing the extent of aging; however, the biochar made from algae alone was the most effective. The algal biochar was found to be an effective antiaging additive delaying aging up to 36%, as evidenced by lower rheology and the chemistry-based aging index compared to those of control bitumen after being exposed to the same aging protocol. Algal biochar was found to be more effective than other studied biochar scenarios owing to its inherently functionalized nature. The latter result could be attributed to the high surface area and rich phenol functional groups in algal biochar, turning it into an effective free-radical scavenger. The study outcome highlights the applicability of this inherently functionalized carbon referred to as biochar in construction to enhance sustainability while promoting the circular economy and the biomass value chain.

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This paper uses a multiscale approach to study the preferential surface adsorption of bio-based rejuvenators to siliceous substrates, used here as surrogates for mineral stones like quartz in bituminous composites. Bituminous composites are the main building blocks of asphalt pavements and roofing shingles. Various rejuvenators, including bio-based rejuvenators, are commonly used to extend the service life or facilitate the recycling of aged bituminous composites reclaimed at the end of their service life. While rejuvenators may be able to restore the thermomechanical properties of aged asphalt, the rejuvenators' susceptibility to moisture damage is a rising concern as various types and dosages of biorejuvenators gain traction in the market.Here, we hypothesize that by controlling the composition of rejuvenators, the adsorption of rejuvenators to siliceous minerals in a wet environment can be increased, leading to enhanced resistance to moisture damage in revitalized aged asphalt. To test this hypothesis, we specifically designed a rejuvenator from a balanced feedstock of algae (high in protein and nucleic acids) and manure (high in lipid), and we compare its resistance to moisture damage with that of two commercial rejuvenators, using molecular modeling and laboratory experiments. Molecular modeling was geared toward simulation, and laboratory experiments were performed using the moisture-induced shear-thinning index (MISTI) and the wheel-tracking test under water. The study results showed that even though the aged asphalt was not susceptible to moisture damage, its moisture susceptibility varied significantly after it was revitalized by each of the three rejuvenators tested. Our molecular simulations showed that water promoted the desorption of molecules of low-performing rejuvenators from the siliceous stone surface, giving rise to moisture damage. This finding was supported by laboratory experiments showing a water-stripping inflection point (SIP) and a significant change in the shearthinning slope after water exposure. The hybrid rejuvenator did not show any evidence of desorption or a stripping inflection point; this can be attributed to the presence of amide-enriched compounds in the hybrid rejuvenator that resulted from feedstock with a balanced combination of protein, nucleic acids, and lipids. The results of this study highlight the importance of accounting for a rejuvenator's composition to ensure that the rejuvenator's introduction to aged bitumen does not negatively impact the durability of the bituminous composite. This is even more critical for severely aged asphalts, which may require a higher concentration of rejuvenators to restore their properties. The study outcome provides insights to formulators and manufacturers to account for durability in their attempts at recycling and resource conservation to enhance sustainability in construction.

This paper examines the merits of coliquefying highprotein algae with high-lipid swine manure to form a bio-oil containing a high concentration of nitrogen-containing fused aromatics to intercalate into oxidized asphaltene nanoaggregates. Such bio-oils can rejuvenate the aged asphalt found in the reclaimed asphalt pavement by restoring the aged asphalt binder's original chemical balance and molecular conformation. In this study, several combinations of high-protein algae and high-lipid swine manure were used to develop biorejuvenators having different concentrations of alkane chains, nitrogen-containing functional groups, and fused aromatics. The study results showed that biorejuvenators made from a combined biomass of algae and manure are more effective than biorejuvenators made from either algae or manure individually, owing to the synergy between lipid-rich swine manure combined with protein-and nucleic acid-rich algae. This blend is called "Swilgae" in this paper. Although all the blends of algae and manure were found to be effective rejuvenators, the blend obtained by liquefaction of a feedstock containing a 4:1 ratio of algae and swine manure was found to be the most efficient combination studied. Our computational analysis showed that molecules present in the Swilgae biorejuvenator have the potential to weaken the π−π interactions within asphaltene stacks and consequently decrease the size of oxidized asphaltene nanoaggregates. In addition, these molecules have a peptizing effect on oxidized asphaltene molecules and are capable of distributing small asphaltene aggregates throughout the medium. The outcome of the study provides an in-depth understanding about rejuvenation mechanism and highlights significant effects of rejuvenators' chemical composition on their efficacy.