Search Results (4)

To reduce vehicle exhaust gas pollution in transport-intensive roadways and tunnels, six types of photocatalytic asphalt binders were designed using graphite-phase carbon nitride (g-C₃N₄) and nanoscale titanium dioxide (nano-TiO₂) particles. In this paper, the rheological behaviors and fatigue life of the nano-TiO₂-modified asphalt binder (TiO₂-MA) and g-C₃N₄-modified asphalt binder (C₃N₄-MA) were investigated. NO degradation capacity of six types of photocatalytic asphalt binders was characterized under visible light conditions. The results showed that TiO₂-MA had more excellent rheological behaviors and rutting resistance than C₃N₄-MA. In addition, 4 wt% nano-TiO₂ markedly improved the rheological behaviors and rutting resistance of MA compared to other dosages. TiO₂-MA exhibited higher fatigue resistance. The fatigue life of TiO₂-MA with 4 wt% nano-TiO₂ was increased to 234.1% at 2.5% strain and 242.5% at 5% strain, respectively, compared to base asphalt binder (BA). C₃N₄-MA had better NO degradation capacity than TiO₂-MA. Meanwhile, the NO degradation efficiency of C₃N₄-MA reached 17.8% with 5 wt% g-C₃N₄. Full article

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. Full article

Transparent binder is used to substitute conventional black asphalt binder and to provide light-colored pavements, whereas nano-TiO₂ has the potential to promote photocatalytic and self-cleaning properties. Together, these materials provide multifunction effects and benefits when the pavement is submitted to high solar irradiation. This paper analyzes the physicochemical and rheological properties of a transparent binder modified with 0.5%, 3.0%, 6.0%, and 10.0% nano-TiO₂ and compares it to the transparent base binder and conventional and polymer modified binders (PMB) without nano-TiO₂. Their penetration, softening point, dynamic viscosity, master curve, black diagram, Linear Amplitude Sweep (LAS), Multiple Stress Creep Recovery (MSCR), and Fourier Transform Infrared Spectroscopy (FTIR) were obtained. The transparent binders (base and modified) seem to be workable considering their viscosity, and exhibited values between the conventional binder and PMB with respect to rutting resistance, penetration, and softening point. They showed similar behavior to the PMB, demonstrating signs of polymer modification. The addition of TiO₂ seemed to reduce fatigue life, except for the 0.5% content. Nevertheless, its addition in high contents increased the rutting resistance. The TiO₂ modification seems to have little effect on the chemical functional indices. The best percentage of TiO₂ was 0.5%, with respect to fatigue, and 10.0% with respect to permanent deformation. Full article

The two major problems that have plagued urban underground roads since their introduction are the harmful emissions caused by hot mix paving and vehicle exhaust accumulation during operation. In order to solve these two problems at the same time, a new asphalt mixture degrading automobile exhaust, which has the advantage of cold mix and cold-application, was presented and studied. A considerable amount of research shows that the use of titanium dioxide (TiO₂) for pavements has received considerable attention in recent years to improve air quality near large metropolitan areas. However, the proper method of applying TiO₂ to asphalt pavements is still unclear. The new mixture presented in this article contains epoxy emulsified asphalt as the binder; therefore, how to apply TiO₂ in the special asphalt mixture proves to be the main focus. By experimental design, four influence factors on the photocatalytic effect, which are the nano-TiO₂ particle sizes, dosage, degradation time, and light intensity, have been investigated. The experimental results showed that the 5-nm particle size of TiO₂ is better than 10–15 nm for exhaust gas degradation, especially for HC and NO; with an increase in the amount of photocatalytic material, the degradation of CO and CO₂ in the exhaust gas did not increase obviously, while the degradation effects of HC and NO were remarkable; in the 4-h time extended degradation test, the experimental data show that the extended time has little effect on the degradation rate of CO₂ and CO, and the general trend is that the degradation of exhaust became significant with the extension of time; while setting a 2-h NO degradation rate as an indicator, to make the index more than 50% or 25%, the average illumination of the road surface cannot be less than 60 lx or 40 lx. Full article