Evaluation of Reductions in Fume Emissions (VOCs and SVOCs) from Warm Mix Asphalt Incorporating Natural Zeolite and Reclaimed Asphalt Pavement for Sustainable Pavements

Investigation of Earth-Abundant Metal Salts for the Inhibition of Asphalt-Derived Volatile Organic Compounds

Asphalt is used globally in construction for roads, pavements, and buildings; however, as a fossil-derived material, it is known to generate volatile organic compounds (VOCs) upon exposure to heat and light that can be harmful to human health. Several heterogeneous strategies have been reported for the inhibition of these VOCs; however, the direct use of inexpensive, accessible Earth-Abundant metals has not been extensively explored. In this study, simple metal salts are examined for their coordination capability toward asphalt-derived VOCs. From UV-visible (UV-vis) spectroscopic studies, FeCl3 emerged relative to other metal salts (metal = Mn, Co, Ni, Cu, Zn) as a promising candidate for the adsorption and retention of Lewis basic compounds. Coordination of an example oxygen-containing VOC, benzofuran (Bf), to Fe yielded a paramagnetic semi-octahedral complex Fe(Bf)3Cl3. Evaluation by thermal gravimetric analysis (TGA) coupled to infrared spectroscopy (IR) demonstrated that the complex was stable up to 360 °C. Spectroscopic evaluation demonstrated the stability of the complex upon visible light irradiation and in the presence of a variety of organic pollutants. The potential application of Fe was demonstrated by subjecting biochar to FeCl3 followed by the addition of Bf. It was discovered that this Fe-rich biochar was successful at adsorbing Bf suggesting the possibility of introducing Fe to biochar late-stage in processing to deter asphalt degradation and VOC emissions. An understanding of the binding and stability of Fe salts to VOCs provides insight into how a sustainable infrastructure can be achieved.

Study on the effect of different aldehyde modifiers on the fume suppression effect, mechanism and road performance of SBS modified asphalt

In order to curb asphalt fume emissions during the heating process of styrene-butadiene-styrene (SBS) asphalt, three aldehyde modifiers [vanillin (X), citral (N) and amyl cinnamaldehyde (J)] were blended into SBS-modified asphalt to prepare aldehyde-modified asphalt in this paper. By collecting solid particles and volatile organic compounds (VOCs) in asphalt fumes to conduct relevant experiments, we have analyzed the fume suppression effect and suppression mechanism of aldehyde modified asphalt, and finally examined the road performance of aldehyde modifiers with the best fume suppression effect. It was found that the average VOCs concentration of aldehyde modified asphalt was reduced by about 78 % after 30 min. Aldehyde modifiers significantly reduce the compositional type and content of VOCs in SBS asphalt and reduce the risk of carcinogenicity by curbing the emission of substances such as benzene and phenol. J asphalt reduced solid particle emissions from SBS asphalt fume by 31.4 % and outperformed both X and N asphalt in inhibiting the escape of solid particulate matter and carcinogens from asphalt fume. Polymer networks and the cross-linking of chemical molecules are the main reasons for inhibiting the escape of asphalt fume molecules. In addition, the J modifier enhanced the high-temperature stabilization and water-stability properties of asphalt mixtures, but slightly reduced the low-temperature cracking resistance. The results showed that the three aldehyde modifiers were effective in inhibiting the volatilization of fumes from SBS modified asphalt. Among them, with the best effect of curbing fume emissions and a better road performance, J-modified asphalt is promising for the application in asphalt fume prevention and emissions reduction, and provides a new solution to reduce construction pollution and physical harm caused by asphalt fume in the construction process.

Upcycling Discarded Shoe Polish into High Value-Added Asphalt Fluxing Agent for Use in Hot Mix Paving Applications

This research effort is geared towards revealing the latent potential of discarded shoe polish that might be repurposed as an asphalt fluxing agent for the construction of durable and sustainable road surfaces. To drive this creative invention, the effect of various proportions of waste shoe polish (e.g., 5, 10 and 15 wt. % WSP) on the performance of base AP-5 bitumen was inspected in great detail. A meticulous investigation of the chemical, physical, and rheological properties of the resultant combinations was carried out using a variety of state-of-the-art laboratory techniques, specifically: thin-layer chromatography-flame ionization detection (TLC-FID), Fourier transform-infrared spectroscopy (FT-IR), needle penetration, ring-and-ball softening point, Brookfield viscometer, ductility, flash/fire points, dynamic shear rheometer (DSR), multiple stress-creep recovery (MSCR), and bending beam rheometer (BBR) tests. The Iatroscan data disclosed that the continuous feeding of binder with WSP had a minor impact on SARA fractional distribution, regardless of aging. According to the FT-IR scan, the stepwise addition of WSP to the binder did not result in any significant chemical alterations in the blends. The combined outcomes of the DSR/BBR/empirical test methods forecasted that the partly bio-sourced additive would greatly improve the mixing-compaction temperatures, workability, and coating-adhesion properties of bituminous mixtures while imparting them with outstanding anti-aging/cracking attributes. In short, the utilization of waste shoe polish as a fluxing agent for hot asphalt mix production and application is not only safe, feasible, and affordable, but it has the potential to abate the pollution caused by the shoe-care market while simultaneously enhancing the overall performance of the pavement and extending its service lifespan.