Laboratory Aging and Annealing of Asphalt Binders by Microwave Radiation

Abstract

A household microwave oven with a frequency of 2.45 × 103 ±13 MHz and an output power of 1000 W is used to simulate short- and long-term aging of asphalt, and for annealing, prior to sampling, to remove steric (isothermal) hardening. A quartz petri dish holds the asphalt during microwave treatment, at atmospheric pressure. To simulate thin film oven (TFO) aging, a 10-g sample is microwaved for a total of 33 min. For 11 asphalts, the average difference in G*/sin δ, at limiting high temperature, between TFO and microwave aging is ±0.68 kPa. Simulating rolling thin-film oven (RTFO) aging is possible by microwaving for a total of 63 min. For 18 asphalts, the average difference in G*/sin δ, at limiting high temperature, between RTFO and microwave aging is ± 1.19 kPa. Aging by RTFO + pressure aging vessel (PAV) and TFO + PAV is simulated by microwaving for a total of 158 min. Microwave aging marginally underestimates long-term aging. For 18 asphalts, the average difference in intermediate temperature obtained after RTFO + PAV versus microwave aging is −2.8°C; for TFO + PAV versus microwave aging, the average difference is −2.7°C. Annealing for 2 hr at 150°C in a convection oven (conductive heating) is simulated by microwaving for a total of 27 min. The average difference in G*/sin δ between the two methods is ±0.24 kPa. Molecular size index (MSI, the ratio of first to second fraction from size exclusion chromatography) correlates with stiffness at low temperature. At intermediate temperature, tan δ remains practically unchanged until MSI reaches a minimum, then increases sharply. At limiting high temperature, G* does not correlate with MSI.

Microwave Heating as an Innovative Road Maintenance Technology: Aging Effect on Binder and Feasibility Evaluation

“…The four main classes of compounds of asphalt components include naphthene aromatics, polar aromatics, saturated hydrocarbons, and asphaltenes, and they are greatly affected by the aging extent of asphalt. Thus, since both the microwave energy and aging are phenomena related to the molecular level [ 31 ], this research employs Fourier transform infrared (FTIR) spectroscopy to detect the chemical functionalities of aged binder by measuring the absorbance intensity of carbonyl groups.…”

Analysis of Reclaimed Asphalt Pavement Heating with Microwave Radiation

“…In numerous papers it was veri ed that the addition of special ferrite materials (especially containing iron) enhances the heating effect of the microwaves on the HMA (Baowen et al, 2020;Yalcin, 2021). In laboratory microwaves were found to be useful to imitate bitumen aging (Bishara and McReynolds, 1995;Li et al, 2019;Mitchell et al, 2013). In the eld of road engineering microwaves were applied in order to synthesize polymers for bitumen modi cation (Alonso-Buenaposada et al, 2016; Ergan et al, 2015) and devulcanization of rubber (Garcia et al, 2015;Xu et al, 2020;Yu et al, 2011).…”

Properties of Porous Asphalt Mixture Made with Styrene Butadiene Styrene under Long Term Oven Ageing

“…The rate of ageing is known to be taking place at a faster rate in porous mixes compared to dense mixes. Many researchers [5,6,7] have been evaluated the ageing effects on asphalt binders since their properties can be easily measured using many conventional tests, such as rotational viscometer, dynamic shear rheometer, bending beam rheometer, and others. However, studies on porous asphalt mixture ageing is rather limited especially its mechanical properties such as stability, resilient modulus, permeability, dynamic creep, air voids and others.…”