Laboratory and Numerical Investigation of Microwave Heating Properties of Asphalt Mixture

Abstract

Microwave heating is an encouraging heating technology for the maintenance, recycling, and deicing of asphalt pavement. To investigate the microwave heating properties of asphalt mixture, laboratory tests and numerical simulations were done and compared. Two types of Stone Mastic Asphalt (SMA) mixture samples (with basalt aggregates and steel slag aggregates) were heated using a microwave oven for different times. Numerical simulation models of microwave heating of asphalt mixture were developed with finite element software COMSOL Multiphysics. The main thermal and electromagnetic properties of asphalt mixture, served as the model input parameters, were measured through a series of laboratory tests. Both laboratory-measured and numerical simulated surface temperatures were recorded and analyzed. Results show that the replacement of basalt aggregates with steel slag aggregates can significantly increase the microwave heating efficiency of asphalt mixture. Numerical simulation results have a good correlation with laboratory test results. It is feasible to use the developed model coupling electromagnetic waves with heat transfer to simulate the microwave heating process of asphalt mixture.

Optimizing Asphalt Mixtures to Be Heated by Microwave

“…Microwave radiation has found different applications in pavement engineering, such as recycling of asphalt pavement [7] and deicing application [8] [9], although most of the researchers used microwave heating to promote self-healing process [10] [1]. When asphalt mixture is exposed to microwave radiation, heat is generated through conversion of the energy of the electromagnetic field [15]. Under the influence of an alternative electromagnetic field, the polar molecules of asphalt mixture attempt to line up (polarize) with the field.…”

“…In the case of asphalt mixture dielectric properties are affected not only by frequency and temperature, but also by other properties of the mixture, such as density, moisture and type of aggregates [21]. Several researchers have simulated the electro-magneto-thermal phenomenon of microwave heating in asphalt mixture by using different simulation models, and different parameters have been considered, such as complex permittivity, complex permeability and some thermal properties [15] [8][17] [7]. In this research, two kind of additives were studied with the aim of optimizing the microwave heating efficiency: Graphene and Electric Arc Furnace (EAF) Slag.…”

Microwave Healing Performance of Asphalt Mixture Containing Electric Arc Furnace (EAF) Slag and Graphene Nanoplatelets (GNPs)

“…The inability of this polarization to follow the extremely rapid reversals of the electromagnetic field generates random motion and inter-molecular friction that produces heat [32,33]. Microwave heating basically depends on the strength and the frequency of electromagnetic field, the dielectric properties of the matter, which represents the efficiency of material in absorbing microwave energy, the conductivity losses and some thermal properties [34].…”

“…Several authors studied the dielectric properties of asphalt mixture for different applications, such as deicing [35], density measurement [36], recycling [33], and maintenance purposes [34,37]. Since the microwave susceptibility of conventional asphalt mixture is low, some authors have added microwave absorbing additives to the mixture for healing purposes [38], such as steel wool fibers [1,19,39,40], steel slag [2,37,41], steel shaving [42], ferrite [17,18] and carbon nanotubes [43].…”

Sustainable Designed Pavement Materials

“…Li et al [14] designed steel fiber modified asphalt concrete to promote the induction heating technology, while Cai et al [15] used engineered cementitious composites mortar to prepare flexible pavement materials with certain healing property. Numerical simulation models of microwave heating of asphalt mixture, which can be used for pavement maintenance, recycling, and deicing, were developed with finite element software by Wang et al [16].…”