The use of asphalt surfacing to enhance the durability of dike infrastructure is well established. In recent years, attention has shifted toward formulations incorporating recycled materials, low-temperature production technologies, and high filler-to-binder (f/b) ratios to support long-lasting performance and sustainability. However, there is a lack of suitable indicators and test protocols at different material scales to monitor field performance of such formulations and support maintenance planning in dike asphalts. Therefore, this study aimed at investigating the ageing sensitivity and stiffness evolution in dike asphalt, using three selected indicators. Field cores were collected from seven test sections at the time of construction and after 5 years. Bitumen and filler were extracted from the cores, and to evaluate ageing sensitivity, the field aged materials underwent short-term laboratory ageing during production of bitumen-filler systems (mastics) using field-representative proportions. Dynamic shear rheometer testing assessed three indicators: the rheological (R) index, crossover modulus (|G_c^*|), and crossover frequency (f_c). The results indicated that f_c decreased significantly (p = 0.01), consistent with increased stiffness and reduced stress relaxation capacity. In contrast, R-index (p = 0.12) and |G_c^*| (p = 0.55) exhibited only marginal changes, indicating limited sensitivity to incremental ageing. Across all indicators, the extent of stiffness change after five years was strongly influenced by the combined effects of binder grade, f/b ratio, recycled content, and field exposure conditions. Overall, the three indicators exhibited consistent aging-related trends, though their sensitivity to distinguish between aging levels varied.

Understanding the effect of realistic in-situ conditions on the mechanical performance of bituminous binders is vital to improve pavement durability. This paper consists of the first effort, at European level, to account for in-situ ageing of bituminous mixtures at different climatic conditions. A reference and five local binders were extracted and recovered upon short-term ageing during production and during the first year of long-term field ageing. The binders have been assessed via Dynamic Shear Rheometer testing for their rutting and fatigue cracking performance, at both ageing states, considering ageing gradients across the pavement depth. The results support a beneficial effect of long-term ageing for the rutting behaviour of the local binders and reveal that ageing mainly takes place within the first 3 cm of pavement depth when examining the fatigue cracking. Overall, this study is the first step towards the development of a robust European ageing model over the course of the following years.

The transition to sustainable pavement materials requires innovative alternatives to traditional mineral fillers that can simultaneously deliver mechanical performance, durability, and reduced environmental impact. This study systematically investigates four geopolymer-based powders derived from fly ash (FAG), metakaolin (MKG), red mud (RM), and slag (S) as substitutes for conventional limestone fillers (WG and WG60K) in asphalt mastic. Rheological testing, chemical characterization, and microstructural analysis are conducted to evaluate their effects on the chemo-structural-mechanical behaviour of bitumen. Results show that FAG markedly enhances high-temperature performance, improving rutting resistance, thermal stability, and shear strength by up to 58%, 45%, and 62%, but exhibits poor fatigue resistance and limited stress-relaxation capacity. In contrast, slag and metakaolin powders offer a more balanced performance profile, with superior fatigue resistance, finer dispersion, and smoother surface morphology (Ra < 1.5 μm), making them promising candidates for durable pavements in warm and moderate climates. RM shows intermediate behaviour, providing good thermal stability but a rougher texture and stronger elastic stiffening. Although no chemical reaction is observed between powders and bitumen, physical interactions such as surface adsorption and alignment of aliphatic chains are found to stiffen the mastic and alter its temperature-dependent response. Surface roughness and dispersion quality are directly correlated with rheological performance, with coarser fillers (FAG, WG60K) enhanced rigidity but shortened fatigue life. Overall, Slag and metakaolin emerge as the most promising geopolymer fillers for durable asphalt pavements.

The utilization of vegetable-based oils as asphalt modifiers has gained significant attention; however, the specific mechanisms by which crude corn oil (CO) enhances self-healing properties—particularly through integrated multi-scale analysis—remain underexplored. This study investigates CO as a sustainable recycling agent intended to restore the self-healing capability of aged asphalt binders. Specifically, it examines the effect of CO on the self-healing performance of a recycled binder (CR) composed of 65% reclaimed asphalt binder (R) blended with a base PG 64–28 binder, using both experimental testing and molecular dynamics (MD) simulations. The research employed simplified viscoelastic continuum damage theory (S-VECD) and pseudo strain energy (PSE) functions to assess damage tolerance, crack generation, and self-healing properties. Damage characteristic curve (DCC) analysis showed that CO had a positive effect on binder rheology, increasing the damage tolerance of the recycled binder and bringing its S -value (a scalar parameter representing material damage evolution) closer to that of the base binder. PSE results further confirmed that CO reduced microcrack formation in the recycled binder. MD simulations were used to evaluate the physical, thermal, and rheological binder properties, and used viscosity recovery (restoration of viscosity following microcrack formation) as a proxy for self-healing performance. The results indicated that CO restored viscosity, effectively rejuvenating the atomistic structure of the recycled binder. However, discrepancies between experimental self-healing (H _exp %) and simulation-based results (H _{s im} %) suggest that density recovery alone may not fully capture self-healing behavior when using the General AMBER force field (GAFF). Overall, this study highlights the complementary value of experimental and simulation approaches for evaluating the effectiveness of CO in enhancing the self-healing properties of recycled binders, offering potential benefits for asphalt pavement durability.

This study investigates the effects of warm-mix asphalt (WMA) additives and bio-oil on the rheological and chemical properties of virgin bitumen (VB) and polymer-modified bitumen (PMB) under varying aging conditions. The workability, viscoelasticity, and chemical characteristic of warm-mix bio-rejuvenated bitumen are assessed using a rotational viscometer, dynamic shear rheometer, Fourier Transform Infrared Spectroscopy. Results show that PMB has superior aging resistance than VB. The wax-based additive exponentially reduces viscosity of VB, while the chemical-based additive decreases viscosity linearly and performs better in PMB due to improved polymer-bitumen interfacial lubrication. The wax-based additive enhances high-temperature elasticity and rutting resistance, whereas adding 0.9 wt% chemical-based additive declines the rutting failure temperature (RFT) of VB by 3.3°C and PMB by 2.3°C. However, the wax-based additive lowers the fatigue life of VB, while the chemical-based additive extends the fatigue life. The fatigue failure temperature (FFT) value increases by 2.3°C for VB and 3.4°C for PMB after adding 4 % wax-based additive. The optimal dosage of the chemical-based additive for PMB is determined to be 0.6 %. The bio-rejuvenator significantly enhances the fatigue performance of aged VB, but has limited impact on aged PMB. Both WMA additives reduce aromaticity and alter aliphatic content, with the chemical-based one showing a stronger dilutive effect, particularly in PMB. Additionally, a warm-mix bio-rejuvenated bitumen with higher aliphatic index (AII) and carbonyl index (CI) shows better deformation resistance and longer fatigue life.

Attenuated Total Reflection Fourier Transform Infrared spectroscopy has become a popular spectroscopic technique in bituminous binder analysis. However, comparable results are not obtainable yet due to differences in devices, measurement routines, sample preparation procedures, and spectral evaluation. Thus, the Task Group 1 of the RILEM TC 295-FBB: “Fingerprinting bituminous binders using physicochemical analysis” focuses on bringing this method towards pre-standardization. This study evaluates the reproducibility and consistency from round robin test, where 21 participating laboratories performed six different preparation techniques on three different binders in an unaged, short-term, and long-term aged state. A total of 6461 spectra were recorded and evaluated for their mean, standard deviation and coefficient of variation (CV) in the spectral region between 1800 and 600 cm⁻¹. The results show that the solid sample preparation methods provide excellent reproducibility, with a coefficient of variation below 2%. Only the solvent method showed a higher coefficient of variation at 7.18%. Outliers with a high CV were detected and categorized into two groups: one where only one of the four samples differed and the other where all 16 spectra showed slight scattering in the overall absorption. The consistency of the method is significantly influenced by the accuracy of sample preparation, which is crucial for minimizing differences in slope, baseline, and noise in the spectra. These findings show the excellent reproducibility of these sample preparation methods and will be further examined to establish universal indices for evaluating effects such as ageing, bringing the method closer towards standardization.

Understanding aging across material scales is critical for predicting the long-term performance of bituminous materials. This study investigates the aging of binder, mastic, and asphalt mixture samples under various temperature, pressure, reactive oxygen species (ROS), and humidity. Chemical aging processes were analysed using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), principal component analysis (PCA), and Euclidean distance. Normalisation, baseline correction, and advanced ATR correction were used to enhance the accuracy of FTIR results. Hydrated lime in mastics enhanced the resistance to oxidative aging, particularly under hygrothermal conditions. PCA identified key spectral regions for understanding aging processes of bituminous materials. Porous asphalt (PA) mixtures aged more than stone mastic asphalt under field-like conditions. PCA identified distinct aging clusters at low and high pressure. Euclidean distance analysis indicated that binder-level aging can approximate mastic and mixture aging under certain conditions. The findings confirm that FTIR indices are effective for multi-scale aging studies.

This recommendation is an output of a small-scale round-robin test involving three different laboratories from TG2 of the RILEM TC 295-FBB: “Fingerprinting bituminous binders using physico-chemical analysis” concerning the use of ¹H-NMR for fingerprinting of bituminous binders. It demonstrates the full capabilities of ¹H-NMR as a robust characterisation tool for complex organic materials, like bituminous binders, to examine their molecular composition in a reproducible way and with the best possible detail. This recommendation documents the key factors in sample preparation and the sensitivity of data post-processing steps. It concludes with best practices and a case study examining the effect of laboratory ageing on two bituminous binders. Overall, it highlights the potential, to the broader scientific community, of another efficient chemometric tool for bituminous binders.

The increasing demand for cleaner and more efficient refining processes has driven the development of advanced upgrading technologies for heavy crude residues. This study investigates a novel Visbreaking-Supercritical Fluid Extraction (SFE) approach to upgrade the Merey vacuum residue (VR), integrating experimental analysis with molecular dynamics (MD) simulations for atomic-level mechanism exploration. The Visbreaking process is optimized at 400 °C for 40 min, achieving a viscosity reduction of 89.0 % while minimizing coke formation. The SFE process fractionates the visbroken VR, with total extraction yields ranging from 70.1 wt% to 70.7 wt%, demonstrating remarkable efficiency. Higher extraction pressures enhance deasphalted oil (DAO) yield but compromise its quality with higher metal and sulfur contents, while lower temperatures improve extraction selectivity. The integrated process effectively removes Fe, Ni, V, and Na, with demetalization efficiencies exceeding 62 %, 75 %, and 95 %, respectively. Molecular dynamics simulations provide atomic-scale insights into solubility mechanisms, revealing that higher pressures and lower temperatures enhance solvent compatibility with lighter visbroken VR fractions. The extracted DAO meets marine fuel oil blending specifications, while raffinates show potential for bitumen production and modification. These findings highlight the Visbreaking-SFE combination as a promising and sustainable upgrading strategy for heavy crude residues.

Oxidative aging induces significant stiffening of asphalt binders that leads to a pronounced reduction in the overall durability of asphalt pavements. The strategic implementation of antioxidant additives provides a potential solution to alleviate this issue. This work presents results from the second phase of the global consortium for antioxidants research aimed at investigating the effectiveness of potential antioxidants in increasing the durability of asphalt binders. Sixteen laboratories around the world participated in this effort and a total of 28 binders from diverse geographical regions were tested. Two promising antioxidants, namely zinc diethyldithiocarbamate (ZDC) and kraft lignin were evaluated in this phase and blended with the binders at specific proportions. Subsequently, a comprehensive investigation was conducted to assess rheological characteristics and chemical properties of the various blends, utilising Dynamic Shear Rheometer (DSR) measurements and Fourier Transform Infrared (FTIR) Spectroscopy. The findings indicate that additives such as ZDC hold considerable promise as an effective antioxidant, particularly when considering a wide diversity of binders. In general, its incorporation does not compromise the rutting performance of the binders and significantly improves fatigue performance. Therefore, research efforts should be focused on exploring additional facets to assess its practical applicability in field.

The objective of this research was to evaluate the lifecycle costs associated with emerging pavement maintenance technologies, namely, in-situ rejuvenation and very open emulsion asphalt concrete (ZOEAB+), and scrutinise their suitability over corrective resurfacing maintenance using a stochastic approach. A rational lifecycle inventory was developed by conducting interviews and questionnaire surveys with experts and referring to standard guidelines and international databases. The net present value (NPV) was found sensitive to 12 different inputs with traffic growth rate and discount rate causing the highest uncertainty followed by gasoline and diesel prices. Monte Carlo simulations suggested that the median uncertainty in NPV by using in-situ rejuvenation and ZOEAB+ was 13% and 4% lower than resurfacing. It is envisioned that the research outcomes will assist decision-makers in understanding the uncertainties and costs associated with different maintenance alternatives in the early stages of the project to foster procurement of sustainable and circular pavement maintenance strategies.

This study aims to correlate the chemical and rheological properties of bitumen at different ageing states and understand the chemical mechanisms of bitumen degradation due to ageing. The relationship between Fourier transform infrared (FTIR) spectral data and rheological results is investigated using partial least squares (PLS) regression integrated with two variable selection methods. The spectral region of 1800 – 800 cm1 is identified as the most informative for accurate estimation of the rheological properties of bitumen. Variable selection methods, particularly moving windows (MW), improve the prediction accuracy of the regression models.