Asphalt mortar is a key constitutive phase in asphalt-mixture mesoscale modeling, but its thermo-rheological characterization usually requires repeated testing over multiple temperatures and loading frequencies, especially across diverse binder systems including rubber-containing modified binders. This study proposes a physics-informed generative adversarial network (PI-GAN) and a physics-regularized multilayer perceptron (MLP) to learn asphalt-mortar viscoelastic master curves from limited experimental data and reduce the burden of repeated mortar-scale testing. A dual-sigmoidal representation with temperature-frequency shifting is adopted, and physical admissibility is enforced during both data generation and prediction through constraints on modulus behavior, phase response, and Prony realizability. A differentiable surrogate is introduced to connect master-curve parameters with relaxation spectra during training. Results from the asphalt-mortar dataset show that about 87% of the raw outputs generated by PI-GAN pass the prescribed physical screening and are retained for downstream training. The physics-regularized MLP substantially improves physical validity while maintaining comparable regression accuracy. Specifically, 96% of the predicted responses satisfy the requirement that the dynamic modulus remains greater than the storage modulus over the full temperature-frequency domain, and 99.7% satisfy Prony realizability. The proposed method provides an efficient route for predicting asphalt-mortar viscoelastic master curves, reducing repeated laboratory characterization, and generating direct constitutive inputs for asphalt-mixture mesoscale finite element modeling.
The widespread application of polyethylene terephthalate (PET) in textiles and packaging has resulted in the continuous buildup of non-biodegradable waste, while current recycling systems are still inadequate to fully recirculate the material. Although recycled polyester (rPET) is widely regarded as a more sustainable option, its full potential remains underexplored. To address this issue, this study proposes a practical and potentially scalable waste recycling and upcycling methodology for transforming rPET chips into functional thermoregulatory filaments, creating a more valuable alternative to virgin polyester (vPET). In this method, rPET chips were carefully dried and subsequently melt-blended with paraffin wax (PW) as a phase change material (PCM), at different loadings from 5 to 20 wt%. This process is followed by melt extrusion to develop continuous thermoregulatory filaments. The reversible phase change behavior of PW within the rPET matrix was confirmed by DSC analysis. The normalized enthalpy of fusion (ΔH) increased from 11.6 ± 0.6 to 47.1 ± 0.7 J·g−1 as the PW content increased from 5 to 20 wt%, respectively. Among the fabricated compositions, the filament containing 10 wt% PW exhibited the most favorable balance between functional and mechanical properties. It delivered a reversible energy storage capacity of 23.4 ± 0.3 J·g−1 while maintaining a tenacity of 51.4 ± 1.2 cN·Tex−1, which is comparable to that typically achieved with virgin PET filaments. Notably, this optimized composition preserved both its thermal storage capability and mechanical strength even after 100 laundering cycles, indicating strong durability under realistic service conditions. The findings confirm that rPET chips can be successfully converted into thermally responsive filaments by directly incorporating PW, thereby offering a practical route for upgrading PET waste into value-added functional products.
Recycled cement paste (RCP) from demolition or industrial waste contains residual portlandite, C-(A)-S-H, and other hydration products that can be valorized by mineral carbonation. Enforced carbonation converts these reactive phases into stable calcium carbonates and pozzolanic alumina-silica gels (AlSi gels), capturing CO2 and producing carbonated RCP (cRCP) suitable as a supplementary cementitious material (SCM). However, the accompanying pH decreases and transformation of cement hydrates during enforced carbonation may destabilize previously immobilized heavy metals, and the mechanisms governing their release and re-immobilization remain insufficiently understood.In this study, the fate of heavy metals in synthetic, heavy metal-doped, and industrial RCPs during enforced carbonation was investigated. Overall, more than 90% of cationic heavy metals were retained in the carbonation products, whereas oxyanions such as Cr and Mo showed enhanced mobility during carbonation. Enforced carbonation of RCP proceeds in two kinetic stages: a rapid initial carbonation of portlandite and AFt/AFm phases, followed by slower decalcification of C-(A)-S-H phases under declining pH. Most cationic metals (Ba, Mn, Ni, Sr, and Zn) were largely retained during the first step and were only gradually released during C-(A)-S-H decalcification. In contrast, oxyanionic Cr and Mo released from AFt/AFm carbonation exhibited early, rapid mobilization and remained largely soluble. These findings demonstrate that enforced carbonation effectively re-immobilizes cationic heavy metals, driven by mineralogical evolution and phase-specific solubility, while simultaneously valorizing recycled materials and mitigating CO2 emissions.
Effective pavement cooling mitigates high-temperature distresses in asphalt pavements while reducing heat accumulation and release to the surrounding environment. While reducing solar heat absorption, the cooling effectiveness of conventional heat-reflective coatings often deteriorates rapidly under service conditions. To address these durability limitations, this study systematically evaluates the long-term cooling performance of a previously developed heat-reflective asphalt thin layer material. A high-precision indoor simulated solar radiation apparatus was employed to quantify baseline cooling performance, while durability was assessed under representative conditioning scenarios, including equivalent ultraviolet accelerated aging, accelerated abrasion, dust and oil contamination, and high–low temperature cycling. The results demonstrate that the heat-reflective asphalt thin layer maintains effective cooling performance under multiple degradation factors. After one year of equivalent ultraviolet aging, the surface cooling effect stabilized at 7.6 °C, retaining 87.6% of the initial cooling amplitude with a reduction of only 1.1 °C. Under severe dust contamination, more than 78% of the initial surface cooling effect was preserved, corresponding to cooling magnitudes of 6.8–7.3 °C. Accelerated abrasion induced a gradual, logarithmically decelerating attenuation, with the surface and bottom cooling effects reduced by 36.3% and 38.1%, respectively, after 30,000 cycles, while residual cooling of 6.2 °C at the surface and 3.3 °C at the bottom was maintained. In contrast, transparent oil contamination and repeated high–low temperature cycling exerted minimal influence on cooling performance. Overall, the heat-reflective asphalt thin layer exhibits superior cooling durability under complex service-induced degradation, demonstrating its suitability as a sustainable and cleaner pavement cooling solution.
The growing demand for repairing deteriorating concrete structures across Europe has led to the increased use of cement-based repair mortars with high clinker content. This induces a high environmental impact. Moreover, it compromises long-term durability, as they are prone to cracking, e.g. induced by restrained autogenous shrinkage, resulting in debonding. This premature failure negatively affects service life and hence, sustainability. As a more sustainable solution, Supplementary Cementitious Materials (SCMs) have gained attention for their ability to reduce clinker content and the environmental impact of repair mortars. This review examines 23 SCMs derived from virgin materials, industrial by-products, and waste streams. It focuses on their availability, key material characteristics influencing reactivity, and performance. To evaluate their technical potential, a comprehensive literature review was conducted, resulting in a database comprising 364 publications. The fresh, mechanical, physical, and transport-related properties, including bond strength, of SCM-based cementitious materials were analysed. These were statistically compared to conventional clinker-rich cementitious materials using boxplots, regression analysis, and the Wilcoxon signed-rank test. This enabled a data-driven comparison across varying replacement levels. The results indicate that certain SCMs (e.g. biochar, LC3, rice husk ash) enhance durability and strength, while others (e.g. steel slag, sewage sludge ash) require careful consideration depending on treatment and dosage. Overall, the study highlights the importance of selecting SCMs statistically based on performance and availability, and advocates for a shift from a “deemed-to-satisfy” strategy towards a “design for durability and sustainability” approach. Although bond strength remains underrepresented in current literature, its role in repair success warrants further investigation.
Scalable reduction of embodied emissions in the built environment increasingly depends on the adoption of emerging structural materials—promising a new era for the construction industry. However, the potential environmental advantages of such materials must be thoroughly scrutinized and systematically evaluated. Life Cycle Assessment (LCA) has been employed as a robust tool to quantify the environmental impact of different products. Nonetheless, variability in the different LCA approaches adopted leads to incongruent results, which subsequently limits both the generalizability and the reliability of LCA pertaining to different product systems. To address such discrepancies, this article considers an example of emerging structural materials to: i) objectively and systematically map the relevant research field; ii) comprehensively appraise how environmental assessments are performed; and iii) critically evaluate these assessments. The analyses of the above findings resulted in iv) identifying key ongoing limitations including: non-transparent reporting, misalignment of LCA stages, unjustified weighting of impact results, and multiple other methodological inconsistencies. To address the latter limitations, the article subsequently introduces a roadmap for developing consistent, transparent, and transferable LCA studies through: v) a multiple functional unit approach; as well as vi) a standardized critical review approach; guided by vii) actionable interventions; to propel viii) better utility and interpretability of environmental impact assessments of emerging structural materials. The roadmap directly supports the development of cleaner construction materials and their necessary evaluation employing LCA approaches.
Novel sustainable foams reinforced with a renewable, functional filler and modified via post-epoxidation were developed for shape memory and self-healing applications. Microcrystalline cellulose (MCC), extracted from durian husk waste, was used as a filler in natural rubber (NR) latex foam. The incorporation of MCC (0.5–2% relative to NR) enhanced the mechanical properties and slightly increased wettability. Post-epoxidation of NR/MCC foams was carried out via a heterogeneous reaction using a formic acid/hydrogen peroxide system, resulting in an NR core/epoxidized NR (ENR) shell structure. This post-epoxidation (5–40% epoxidation) significantly improved the mechanical properties and wettability while imparting shape-memory and self-healing functionalities. Overall, this approach demonstrates a simple and sustainable strategy for the development of smart materials.
The transformation of lignin into a valuable biomaterial offers an innovative approach to sustainable packaging and a circular bioeconomy. In this study, we have developed sustainable films based on a polyvinyl alcohol-polyethylene glycol copolymer with internal plasticizing properties, reinforced with renewable dealkaline lignin as the active ingredient, thereby eliminating the need for external plasticizers. The films were developed using a solvent casting technique and were analyzed for their mechanical strength, flexibility, barrier properties, and functional performance. The integration of lignin (at 10 wt%) with the polymer synergistically enhanced the tensile strength to 10.35 +/- 0.2 MPa, the water contact angle to 71.2 +/- 4.8 degrees, and the UV-blocking ability to 84% across the UV range. Additionally, the films demonstrated reduced water vapor and oxygen permeability, thereby enhancing overall barrier performance. The characterization techniques like FTIR and XRD indicated strong intermolecular interactions and amorphization in the composite films, while TGA confirmed better thermal stability than blank films. Beyond their physical attributes, the films exhibited improved antioxidant activity and significant antibacterial activity against common foodborne pathogens (Escherichia coli and Staphylococcus aureus). Further, the finalized film batch effectively inhibited visual browning and prolonged the shelf life of fresh-cut bananas, as demonstrated by 5-day preservation studies. Soil burial tests confirmed the physical disintegration of the films within 12 days, highlighting the potential of lignin as a high-value additive in a PVA-PEG copolymer matrix for a sustainable, eco-friendly food packaging solution.
This study investigates the potential of a novel geopolymer binder, synthesized from water treatment sludge (WTS), silica fume (SF), and a recycled liquid alkaline activator (RLAA), for the stabilization and solidification (S/S) of construction and demolition (C&D) waste contaminated with Pb and Cd. For this purpose, response surface methodology (RSM) was used to design and optimize the experiments by assessing the combined effects of WTS content, SF content, and heavy metal (HM) concentration through two 17-run Box–Behnken design matrices. The mechanical performance and leachability of the samples were evaluated after 28 days of curing using unconfined compressive strength (UCS) and toxicity characteristic leaching procedure (TCLP) tests, while the results were further verified through a set of microstructural analyses. The findings revealed that the optimal mechanical performance was achieved in Pb-contaminated samples with 15% SF and 5% WTS and Cd-contaminated samples with 15% of both additives, with all stabilized samples exhibiting significant strength enhancement (UCS>1000 kPa) from the WTS and SF addition. Moreover, the immobilization efficiencies of Pb and Cd exceeded 97%, while the leachate concentrations were far below the EPA regulatory limits. The high correlation coefficients of the developed RSM models (R2 = 0.953 for UCSPb, 0.974 for S/S efficiencyPb, 0.973 for UCSCd, and 0.995 for S/S efficiencyCd) demonstrated their strong predictive capability for both strength and leachability. These results confirm that the synergistic use of WTS, SF, and RLAA provides a cleaner-material geopolymer binder that converts multiple industrial waste streams into a value-added stabilization material, reducing dependence on Portland cement and commercial alkaline activators, while providing a sustainable and highly effective approach for the S/S of HM-contaminated construction waste.
The incorporation of biochar into cementitious systems has attracted growing attention as a strategy to enhance concrete performance while contributing to carbon sequestration and sustainability in construction materials. The structural characteristics of biochar evolve significantly depending on feedstock origin and production conditions, leading to considerable variability in its behaviour within cement matrices. This review critically examines how feedstock diversity and key production parameters, including pyrolysis temperature, activation, and post treatment, govern the structural and physicochemical properties of biochar, such as pore structure, surface area, functional groups, mineral composition, and morphology. These characteristics determine the functional roles of biochar in cement composites, influencing workability, hydration processes, strength development, thermal behaviour, and durability performance. Biochar derived from agricultural residues, woody biomass, and biosolids is comparatively evaluated to highlight how different feedstocks contribute to performance enhancement and carbon sequestration potential in cementitious materials. Despite these promising advantages, challenges remain in optimising biochar dosage, ensuring compatibility with cement hydration, and balancing mechanical performance with environmental benefits. Key knowledge gaps and future research directions are identified to guide the development of high performance and sustainable biochar based cementitious materials.
Stone Matrix Asphalt (SMA) and high-level Superpave mixtures are widely used in the United States due to their durability and suitability for heavy traffic, but they typically require high-quality aggregates that are costly and not always locally available. Identifying feasible, cleaner, and cost-effective local aggregate alternatives is therefore critical for sustainable pavement construction because they can reduce transportation-related emissions, conserve natural aggregate resources, and improve supply-chain sustainability. Previous work demonstrated acceptable aggregate properties and promising laboratory performance for several Missouri aggregates (gravel, steel slag, chat, limestone, and dolomite) used as alternatives to standard-specified aggregates like traprock in SMA and high-level Superpave mixtures, but the evaluation was limited to material-level testing.This study extends that effort by assessing pavement-level performance and life-cycle cost-effectiveness of these mixtures. Laboratory-measured material properties were used as inputs to mechanistic pavement simulations to predict fatigue, rutting, and thermal cracking over a 20-year design life using a representative pavement structure under site-specific traffic and climate conditions. A life-cycle cost analysis (LCCA) was conducted based on material costs and predicted rehabilitation timing.The results indicate that SMA mixtures with alternative aggregates exhibited slightly higher predicted fatigue damage than the control mixture, while high-level Superpave mixtures showed minimal differences. Rutting resistance of candidate mixtures was comparable to or better than that of the control mixtures, and all mixtures were predicted to perform adequately against thermal cracking under local minimum pavement temperatures. The LCCA results demonstrate that all alternative aggregate mixtures are more cost-effective than the controls. Overall, the findings support the use of locally available alternative aggregates as cleaner materials capable of delivering satisfactory pavement performance while improving the economic and environmental sustainability of asphalt pavement construction.
Poroelastic road surface (PERS) pavement is currently the low-noise pavement with the best noise reduction potential. However, its composition design varies significantly from one researcher to another and poses great difficulties in practical application. This article reviews the development history of PERS, summarizes current research on its composition design and pavement performance, and provides an outlook on future developments. The review shows that two types of PERS mix compositions — rubber-skeleton and aggregate-skeleton PERS — are used in different ways. PERS exhibits exceptional noise reduction capacity, sufficient strength and mechanical properties, but relatively poor water resistance. The design featuring high air void and rubber content poses challenges to its durability, which necessitates a balance between noise reduction capability and mechanical properties of PERS from the perspective of mix design. The proposed on-demand design philosophy provides a foundational framework for guiding the mix design of PERS to meet specific noise reduction requirements and accommodate diverse traffic conditions. Further investigation is required to establish the fundamental design principle and develop high-efficiency, cost-effective binders for durable PERS mixtures.
Textiles and fashion industries face increased pressure to reduce their environmental footprint, as conventional dyeing and synthetic leather production, consuming large amounts of water, resources, and energy as well as generating persistent pollutants. Bacterial cellulose (BC) offers a sustainable alternative due to its high purity, biodegradability, and mechanical strength. However, integrating pigmentation during BC biosynthesis has been hindered by incompatibilities between melanin production and the acidic conditions required for efficient BC formation. In this study, we present a one-pot, one-step co-culture strategy combining Komagataeibacter xylinus with engineered Escherichia coli expressing an acid-tolerant tyrosinase variant (TyrMut_Pm) designed through rational in silico mutagenesis. TyrMut_Pm exhibited a 2.07-fold higher initial activity at pH 5 compared to the wild-type enzyme (1.284 & times; 10- 2 versus 6.209 & times; 10-3 Delta A405/min), directly enabling melanin biosynthesis under the acidic conditions of BC fermentation and eliminating the need for secondary development baths, while maintaining efficient cellulose production and reducing process complexity. The resulting melanised BC exhibits leather-like properties after glycerol-assisted leatherisation, with tensile strength and flexibility comparable to synthetic vegan leathers, alongside excellent colour fastness and full biodegradability under composting conditions. Through the rational design of an acid-tolerant tyrosinase integrated into a one-pot co-culture, this study establishes a rigorously validated biomanufacturing platform that synchronises melanin biosynthesis with bacterial cellulose assembly. By eliminating conventional multi-stage dyeing and minimising water, energy, and chemical inputs, this approach delivers a scalable, fully characterised bio-composite that advances the cleaner materials paradigm through a circular, low-impact alternative to petrochemical synthetic leathers.
Steel slag concrete (SSC) piles represent a resource-efficient option for ground improvement as they valorize steelmaking by-products and reduce dependence on conventional cement and natural aggregates. The major novelty of this study is the field-scale in situ verification of SSC pile composite foundations and their direct comparison with traditional fly ash cement concrete (FCC) piles through a combined macro–micro analysis. This study assessed SSC pile composite foundations using full-scale static load tests coupled with multi-scale material characterization. The results indicated that the SSC and FCC single-pile composite foundations developed comparable ultimate capacities, reaching approximately 2.1–2.4 times that of the natural-site soil. Nevertheless, the SSC foundations demonstrated more favorable pile–soil interactions, which were expressed through a stable and relatively small pile–soil stress ratio and a more effective mobilization of inter-pile soil resistance. Microstructural analyses at 100 and 360 d revealed that SSC formed a denser hydration matrix, a more coherent interfacial transition zone, and a rougher, better interlocked pile–soil interface enriched with hydration products and soil inclusions. These microstructural features underpinned the improved settlement behavior and sustained load-transfer capacity observed during field testing. After one year under dredger-fill conditions, SSC retained low porosity and strong interfacial bonding. This indicates promising durability compared with FCC under the investigated field conditions. Under the adopted A1–A3 calculation boundary, each SSC pile incorporated approximately 0.7 t of steelmaking by-products and showed a preliminary embodied carbon advantage at the material stage compared with FCC. Overall, SSC piles can provide reliable structural performance and a performance-based basis for future optimization- and sustainability-oriented assessments under dredger-fill ground conditions.
The microstructure of warm mix recycled asphalt and the interactions among its components play a crucial role in determining its rheological properties. This study investigates the effects of aging, rejuvenators, and warm mix agents on the resistance to permanent deformation, fatigue characteristics, and microstructure of SBS-modified asphalt. The interactions among asphalt, rejuvenators, warm mix agents, and SBS molecules were investigated using a combination of Dynamic Shear Rheology (DSR), Multi-Stress Creep Recovery (MSCR), and Linear Amplitude Scanning (LAS) tests, alongside Atomic Force Microscopy (AFM), Molecular Dynamics (MD) simulations, and Density Functional Theory (DFT). The results indicate that REJ adversely affects the high-temperature deformation resistance of aged asphalt (AA) but exerts a positive effect on its fatigue resistance; WMA can enhance the high-temperature deformation resistance of aged asphalt and prolong its fatigue life. Furthermore, polar rejuvenator molecules are more likely to be distributed in the SBS-containing phase or near the SBS–asphaltene interfacial region, whereas Fischer–Tropsch (FT) wax molecules exhibit a slight aggregation tendency because of their relatively weak interaction with SBS macromolecules. Molecular simulations suggest that REJ and WMA mainly regulate the SBS–asphalt interfacial region and the aggregate structure, rather than being uniformly dispersed inside SBS itself. DFT analysis further reveals that specific atoms within both the rejuvenator and warm mix agent exhibit strong electrostatic interactions with polar molecules present in aged asphalt—particularly with -CHO and -COOH groups found in SB- and BS-components. This paper explores the mechanisms underlying interactions between aged asphalt, rejuvenators, and warm mix agents from macro-, micro-, and molecular perspectives, thereby providing valuable insights for applications involving warm mix recycled asphalt.
Metal-Organic Frameworks (MOFs) are a new type of porous material with large surface areas, configurable porosity, and with potential for a wide range of applications due to their chemical and structural tunability. They are also observed to have diverse applications in gas storage, catalysis, and environmental remediation, among others. However, in traditional MOF synthesis processes, the requirements for high-purity metal salts and conventionally derived organic linkers are often expensive, environmentally unsustainable, and hence hinder MOF commercialisation efforts. Recent progress in MOF synthesis using unconventional precursors is changing the narrative. This review article focuses on recent advances and challenges for the use of naturally occurring inorganic minerals, biomass-derived linkers, and industrial metal-rich waste materials as unconventional feedstocks for MOF synthesis. The study categorises these alternative materials based on their chemical makeup and suitability, while also examining their impact on the structure and function of MOFs. The review's findings suggest that employing unconventional precursors is a viable technique for producing MOFs in an inexpensive and sustainable manner. The study further emphasises the need for more research into the environmental implications of large-scale use, precursor reactivity, and structural integrity. The proposed approach of using alternative or unconventional precursors presents new opportunities for integrating MOF synthesis strategies with circular economy approaches.
Wood flour is an abundant wood waste from timber-based industries, but is of low value and is a hazard. To improve the sustainability of these industries and increase the intrinsic value of wood waste, there is merit in valorising it by incorporating mycelium to fabricate mycelium-bound composites. Such composites are known sustainable alternatives to conventional materials such as particle boards and polystyrene foams. In this study, an ink utilizing bamboo wood flour and bentonite that can support mycelium growth was developed to fabricate complex structures using extrusion-based 3D printing. The resulting ink could be printed into scalable structures with length scales ranging in order of magnitude from millimetres to centimetres. The presence of solid particles reduced shrinkage to 30.4 ± 5.2% when dried in oven. The presence of mycelium increased the compressive Young's modulus and ultimate strength by 756 ± 424% and 139.1 ± 34.3% respectively, the contact angle by 72.2 ± 10.2%, the thermal insulation by 30.2 ± 1.3% and the resistance to natural weathering of composites when exposed to tropical conditions over 28 days. Using 3D printing, complex structures with improved thermal insulation could be fabricated, where the design of the shape has a greater contribution than the presence of mycelium. This shows the potential for sustainable upcycling of wood waste to fabricate complex structures that can be tailored to meet the needs of various applications.
The electronics industry urgently seeks sustainable, biodegradable alternatives to conventional substrates for printed circuit boards (PCBs) to reduce the environmental impact of electronic waste and CO2 emissions. Here, we introduce a biobased, plastic-like material derived from Aspergillus niger mycelium, AnimatRT. This material is produced from residual biomass generated in industrial citric acid production, offering a circular-economy approach. The raw mycelial biomass, consisting of spherical pellets, is processed via mold casting and air-drying, consolidating the pellets into a dense, plastic-like monolith (1.23 g cm-3). When formed into sheets, AnimatRT serves as a viable substrate for low-complexity PCB fabrication, allowing for direct ink writing and manual soldering of electronic components. Although its electrical properties are lower than those of FR-2 (flame retardant 2), a common, low-cost PCB laminate made of paper bonded with a phenolic resin, it remains suitable for low-frequency and proof-of-concept applications and, on average, has 56% lower embodied carbon. The mycelium boards disintegrate in water, allowing recovery of operative electronic components, whose functionality was demonstrated by re-soldering them onto a conventional PCB. The material exhibits high mechanical performance, with compressive strengths of up to 121 MPa, a flexural modulus of 2.3 GPa, and a flexural strength of 30 MPa. It is fully biodegradable (ISO 20200), redispersible in water, has low flammability, and favorable thermal insulation properties (0.21 W (mK)-1). Heat treatment at 120 degrees C enhances the mechanical properties, improves water resistance, and slows biodegradation. This study demonstrates the first use of biotechnology-derived A. niger mycelium as a biodegradable substrate for PCBs, addressing circularity and end-of-life challenges in electronics.
Recycling end-of-life asphalt is essential for sustainable pavement construction yet ageing-related chemical changes in asphalt binders increase viscosity and limit recyclability. Low-viscosity, biomass-derived additives are increasingly used to restore aged binder properties, but their chemical diversity and true bio-based content remain insufficiently understood. This study provides a detailed chemical categorization of 20 commercially available bio-additives and evaluates their suitability for asphalt recycling. Infrared spectroscopy enabled classification of the additives into six families (acids I and II, esters I and II, phenolics I and II) based on characteristic absorption patterns. Complementary one- and two-dimensional NMR analyses further distinguished structural features such as saturation levels, chain lengths, and aromatic/aliphatic composition. Radiocarbon (14C) analysis was applied to selected additives to verify their biogenic origin, revealing three groups: fully biogenic products, predominantly biogenic materials modified with fossil-derived components, and additives dominated by fossil carbon. This demonstrates the value of 14C measurements as a robust tool for certifying bio-based content. Several low-viscosity additives from the acid I, esters I/II, and phenolic I families were blended (5–10 %) with binders extracted from reclaimed asphalt pavement (RAP). Dynamic Shear Rheometry confirmed effective restoration of rheological properties across multiple combinations. Finally, FTIR- and NMR-based approaches for assessing oxidation state and quantifying additive content were evaluated, highlighting both their potential and method-specific limitations.Overall, this study delivers a practical chemical–rheological framework for classifying bio-additives, verifying their bio-based content, and providing tools for improved evaluation of aging state and bio-additive content, supporting the development of more sustainable asphalt materials.
The sustainable development of transportation-energy systems increasingly relies on traffic monitoring and dissipated mechanical energy harvesting technologies. Triboelectric nanogenerator (TENG) enhanced pavements offer such potential, but their life cycle implications remain insufficiently understood. In particular, it is unclear whether integrating TENGs into pavement structures reduces or increases overall life cycle cost, energy use and carbon emissions once material production, construction and long-term operation are considered. This study addresses this gap by conducting a cradle to grave assessment of the environmental and economic impacts associated with embedding vehicle-side TENGs (V-TENGs) and road-side TENGs (R-TENGs) into transportation-energy systems. Four pavement configurations, including conventional asphalt pavement without V-TENG, tribo-inspired smart pavement without V-TENG, asphalt pavement with V-TENG and tribo-inspired smart pavement with V-TENG, are evaluated using energy payback period, Levelized Cost of Energy (LCOE), environmental profile and sensitivity analysis across human health, resource depletion and ecosystem quality. Results show that TENG integration effectively captures wasted mechanical energy and contributes to lower life cycle energy consumption and carbon emissions while maintaining a balanced overall environmental burden. These findings provide quantitative evidence for the sustainability benefits of TENG enabled smart pavements and offer practical guidance for their future large-scale deployment within transportation infrastructure.
