This research presents a dual-pronged bibliometric and systematic review of the integration of phase change materials (PCM) in asphalt pavements to counteract the urban heat island (UHI) effect. The bibliometric approach discerns the evolution of PCM-inclusion asphalt research, highlighting a marked rise in the number of publications between 2019 and 2022. Notably, Chang’an University in China has emerged as a leading contributor. The systematic review addresses key questions like optimal PCM types for UHI effect mitigation, strategies for PCM leakage prevention in asphalt, and effects on mechanical properties. The findings identify polyethylene glycols (PEGs), especially PEG2000 and PEG4000, as prevailing PCM due to their wide phase-change temperature range and significant enthalpy during phase transitions. While including PCM can modify asphalt’s mechanical attributes, such mixtures typically stay within performance norms. This review emphasises the potential of PCM in urban heat management and the need for further research to achieve optimal thermal and mechanical balance.

Some researchers have used the fine aggregates matrix (FAM) as a means to evaluate the influence of material properties on the expected changes in the performance of hot mix asphalt (HMA). Based on the most commonly used definition, the FAM is composed of part of the fine aggregates (smaller than 1.18 mm), mineral filler, and asphalt binder. Different studies have used different methods to design such FAM mixes. In this study, the fatigue characteristics of different FAM designs (by varying their maximum aggregate size and binder content) were evaluated and compared to the fatigue characteristics of a corresponding full asphalt mixture. The goal of this exercise was to identify a FAM design that was most similar to the full asphalt mixtures in terms of its damage characteristics. The viscoelastic continuum damage approach was used to make such comparisons. Results show that FAM mixes with a maximum nominal aggregate size (MNS) of 2.00 mm have similar damage evolution trends as that of the full hot mix asphalt with a maximum aggregate size of 12.50 mm. Also, through the results and using a failure criterion based on energy, cyclic tests can be simulated at different loading conditions in order to construct Wöhler curves. The results showed that smaller MNS mixtures present better damage performance for strain levels lower than 500 microstrain.

This work focuses on modeling fatigue for aged asphalt mixtures. This is accomplished by combining existing models and adapting asphalt mixture aging laboratory procedures. The aging model used is based on the evolution of an internal state variable, and it is capable of taking into account the effect of aging temperature. The simplified viscoelastic continuum damage (S-VECD) model was selected for representing the fatigue damage behavior. Results at four aging states were analyzed, including the unaged mixture. Aged mixtures were obtained by heating loose asphalt mixture in an oven for two periods (2 and 45 days) and two temperatures (85 and 135°C). Based on the results from linear viscoelastic and S-VECD characterization, it was concluded that aging produces less damage tolerant materials; i.e., fatigue failure is observed for less evolved damage states. However, depending on the pavement conditions and on the pavement cross section geometry, because of the increase in material stiffness, aging ...

Aging by oxidation of asphalt roadway material promotes changes in its physical, chemical, and rheological properties, affecting its hardening and accelerating the degradation of its corresponding asphalt mixture. Titanium dioxide (TiO₂) has been applied in engineering investigations to promote anti-aging and photocatalytic properties. In this study, a commercial binder was modified with nano-TiO₂ (using contents of 0.1, 0.25, 0.5, 1, 2, 3, and 6%). It was evaluated by physicochemical and rheological tests (penetration, softening point, mass loss, dynamic viscosity, rheology, and Fourier transform infrared spectroscopy—FTIR) before and after aging by rolling thin-film oven test (RTFOT) and pressure aging vessel (PAV). The results indicated that incorporating nano-TiO₂ mitigates binder aging, pointing out 0.25% as an optimum modification content for the investigated asphalt binder.