No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Snow and Ice Melting Properties of Self-healing Asphalt Mixtures with Induction Heating and Microwave Heating
Abstract
In this paper, the snow and ice melting properties of self-healing asphalt mixtures with induction
heating and microwave heating were investigated. The self-healing performance of the mixtures during
ice melting process was measured with cyclic three-point bending test as well. The results indicated that
the snow and ice melting performance of self-healing asphalt mixtures with appropriate heating
techniques was remarkable. The average melting velocity of ice melting was improved from less than
1g/min (previous researches) to more than 10g/min, while the average snow melting velocity of steel
fiber modified asphalt mixture and steel slag asphalt mixture with microwave heating could reach
53.9g/min and 48.5g/min respectively. The water from melted ice/snow played a major role in the
melting process of snow with microwave heating. However, the moisture from melted ice/snow on the
surfaces of crack prevented the thermal healing of asphalt mixtures. It is recommended that another
heating process after the melting process should be applied to promote the healing of cracks as well as
to prevent the melted snow and ice water on the pavement from freezing.
Supplementary resource (1)
... Moreover, self-healing is also known as a very complex physicochemical process. e molecular diffusion healing mechanisms in asphalt materials are derived based on selfhealing polymeric systems, which describe its self-recovery behavior based on polymer chain dynamics [18]. Wool and O'Connor [19] divided the theory of crack healing into five stages based on molecular interdiffusion. ...
... Based on such observations, Xu et al. [24] recommended the use of short and thick steel wool fibers with a diameter of 70-130 µm and length 4.2 mm because it is quite easier to mix using the standard mixing procedure at an optimal steel wool content of 6% by the volume of bitumen. Nonetheless, some studies such as those conducted by Ameri et al. [31] and Sun et al. [18] replaced a portion of the aggregate from the asphalt mixture with steel slags as conductive materials by which they attested to the fact that the steel slag-asphalt mixture showed a better performance in healing when the temperature distribution was more uniform. Furthermore, laboratory test results also evidently indicated the use of coarse steel slag aggregates in warm mix asphalt (WMA) mixture in the enhancement of the tensile strength, resilient modulus, Marshall stability, resistance to moisture damage, and resistance to permanent deformation of the mixture [31]. ...
... mm and 0.5 mm length to width, respectively. Recent findings have established microwave heating to be more advantageous than induction heating in terms of its high heating efficiency (rapid heating), no direct contact with liquids, no air emissions, fast thermal response, precise temperature control, and selective energy absorption [18,42,43]. e rapid increase of total energy means that the sample can absorb more energy to increase the temperature [44]. ...
The concept of self-healing has an excellent potential to extend the life of asphalt pavement. This technology can be considered a sustainable technology due to its ability to reduce the utilization of asphalt mixture production materials used for road maintenance, polluting the environment. It is a complex physicochemical process wherein the molecular diffusion healing mechanisms in asphalt materials are inspired by self-healing polymeric systems, which describe the self-recovery behaviors based on polymer chain dynamics. Several methods have been adopted to improve the self-healing of asphalt, one of which is induction healing. It is the process of heating the asphalt pavement incorporated with an electrically conductive material such as steel fibers, wherein asphalt healing is undertaken via electric field induction. Induction healing via induction heating occurs with eddy current where the electric current flows within the conductive fibers when magnetically susceptible under the magnetic field. Microwave heating is another self-healing method similar to induction in which magnetic radiation is employed to treat asphalt mixtures instead of the electric field-induced induction healing processes. The conductive fibers can absorb the electromagnetic (EM) waves to convert them into heat energy through doublet polarization, interface polarization, and electrical conduction dissipation when placed in the microwave field. These two types of heating systems, which are induction heating and microwave heating, are compared and discussed thoroughly in this study. Finally, some recommendations for the future development of self-healing asphalt are proposed.
... Conductive asphalt mixtures have served as the base technology for pavement deicing (self-heating or electrical heating) and self-healing asphalt mixtures. As an example, Sun et al. [37] reported on the deicing and snow melting applications of self-healing asphalt mixtures using thermal conductivity and microwave induction heating. In Sun et al.'s research, self-healing asphalt mixtures showed a desirable deicing performance under microwave heat induction, exhibiting a high deicing rate and efficiency [37]. ...
... As an example, Sun et al. [37] reported on the deicing and snow melting applications of self-healing asphalt mixtures using thermal conductivity and microwave induction heating. In Sun et al.'s research, self-healing asphalt mixtures showed a desirable deicing performance under microwave heat induction, exhibiting a high deicing rate and efficiency [37]. In another study, Liu et al. investigated the self-healing capabilities of warm mix asphalt (WMA) and hot mix asphalt (HMA) using induction heating; this study reported comparable induction heating speeds, with both asphalt mixture types observing a slightly lower HI for WMA. ...
... where m (in g) is the total weight of ice before heating; m (in g) is the total weight of ice after heating, normalized by the weight-loss of ice during the same period within a microwave field with the same power, and t (s) is heating duration. A more detailed description of this testing method can be found in [37]. ...
This study evaluates the influence of polymer-modification on the induction heating capability of asphalt mastic in a microwave field, and investigates how effectively this approach can be utilized for ice melting and self-healing purposes. To this end, different asphalt mastic mixtures with different polymer-modification and mixing procedures were tested under microwave field exposure for induction heating capability, ice-melting ability, and self-healing capacity. The mixtures were made through warm-mix and hot-mix procedures with four bituminous binders, including virgin (unmodified) asphalt and the same binder modified with three types of polymers. The results showed the effectiveness of microwave induction heating of asphalt mastic for both crack-healing and deicing purposes. The binder type was found to influence the ice melting and crack healing rates, such that using a warm-mix asphalt binder resulted in a more efficient heat generation and conduction than using a virgin asphalt binder. While polymer-modification undermined induction heating, ice-melting, and self-healing performances, SBS-modified asphalt binders exhibited better performance than the other polymer-modified binders.
... Microwaves are a part of the electromagnetic spectrum with frequencies ranging from 300 MHz to 300 GHz, lying between infrared and radio frequencies. Microwave technologies were developed rapidly during and after the Second World War for radar and communication uses [1,2]. These days, microwaves are extensively used for wireless communications, such as long term evolution; for major wireless local area network standard (Wi-Fi); space craft communication and radar applications like global positioning system; and air traffic control [3,4]. ...
... The stronger the palletization on the surface, the easier it is to form soil. In other words, high organic matter content makes it easier to form clay-organic compounds, which in turn facilitates soil cementation [2,7]. Usually, structures of soils are destroyed during microwave digestion because microwaves cause the temperature in the soil surface to rise. ...
Thermal treatment has long played a significant role in ex-situ soil remediation. Although it has a significant effect on eliminating semi-volatile and volatile organic compounds and is highly applicable to partial remediation of severely-contaminated soils, there are still limitations to such technology. On the other hand, not only can microwave heating treatment conserve time and energy, but it is also eco-friendly and can overcome difficulties encountered when applying traditional heating methods. Hence, microwave heating treatment will become a valuable technology for soil remediation in the future. Based on this observation, this study first applied microwave heating treatment to Taiwanese soil, a Taikang (Tk) series soil, and we observed factors that caused the temperature of the soil to rise. Then, we prepared a glyphosate-contaminated Tk series soil to simulate the degradation of high-concentration glyphosate in the soil. The soil reached 1000 o C in 5 min after being heated, indicating that microwave heating treatment largely outperformed traditional heating methods. Moreover, the results show that the rate of the rise in temperature is related to the amount of crystalline iron and quartz contained in the soil because the Tk series soil contains more than 15 g of crystalline iron oxide per kilogram. In terms of the relationship between heating time and the degradation of glyphosate, this study found that the degradation rate of glyphosate in the Tk series soil reached up to 99% after being heated with microwaves for 35 min. This outcome suggests that microwave heating treatment is an effective and efficient measure to degrade glyphosate in the soil. Microwave heating treatment has been widely adopted for the remediation of soil and underground water treatment sites. These findings can serve as references for the government in terms of soil restoration in the future.
... Deicing technology using conductive asphalt mixtures has been conceded as the bases for developing pavement self-healing techniques (Minsk 1968). In this regard, Sun et al. (2018) investigated ice and snow melting properties of self-healing asphalt mixtures using microwave heating and thermal induction. The self-healing performance of the asphalt mixture during the ice melting process was investigated using a three-point bending beam test. ...
... The results showed that increasing the deicing speed of self-healing asphalt mixtures using a proper heating technique was significant. Sun et al. (2018) showed the higher efficiency of the microwave heating method than induction heating for ice melting. Presently, self-healing capability utilizing such reproducible techniques has received much attention in asphalt pavement maintenance projects (García et al. 2014(García et al. , 2013Liu et al. 2011;Ayar et al. 2016). ...
Nowadays, regarding the scarcity and non-renewability of natural resources and environmental issues, the use of waste materials in asphalt mixtures has become very popular. Research findings show that the use of Basic Oxygen Furnace (BOF) slag
in asphalt mixtures improves mechanical properties and increases economic efficiency. The main objective of this study is to investigate the feasibility of using BOF slag as a filler in Warm Mix Asphalt (WMA) in terms of moisture susceptibility, deicing and self-healing characteristics. The freeze–thaw cycles were employed to evaluate the moisture susceptibility of these mixtures. Moreover, deicing tests using microwave heating, namely ice-melting capability, ice falling time and self-healing during deicing of WMA samples, have been carried out incorporating different BOF contents (0, 35, 70, and 100
by total filler weight). In the next step, self-healing and heat transfer tests were performed using surface thermal imaging method. Based on thermal imaging results, the asphalt mixture’s heat transfer and heating rate increase with increasing BOF content. The results also show that the best self-healing level was achieved by complete filler replacement with BOF. In this regard, the self-healing level of the WMA containing 100% BOF slag improved by 22% on average after five self-healing cycles compared to the control mixture (containing limestone filler). Furthermore, the ice melting speed of WMA containing
100% BOF filler was 56% higher than that of the control mixture.
... Some scholars have applied microwave heating to remove ice on asphalt pavements [15][16][17][18]. This method enables the ice in contact with the road to melt quickly [19][20][21][22]. In addition, this microwave heating de-icing method also helps the asphalt binder self-healing [23]. ...
... They found that carbon fiber's absorption and heating efficiency in asphalt mixture improves as carbon fiber length increases. Sun et al. [20] studied the melting snow performance of asphalt mixture modified by steel fiber under microwave and induction heating. The deicing efficiency of microwave heating is much higher than that of induction heating. ...
In winter, icing greatly reduces the friction performance of pavement and brings a high safety hazard to road traffic. We prepared a superhydrophobic coating (SHC) with a microwave heating function to minimize pavement icing risk. The static contact angle of the water droplet on the SHC is 161.2°. The freezing time of water droplets on asphalt mixture coated with SHC is 1.63 times longer than that of asphalt mixture without coating. SHC can significantly delay the freezing process of water. The normal adhesion strength of 10 mm ice layer on the asphalt mixture coated with the SHC at −5 °C is only 14.3 % of that on the asphalt mixture without coating. It confirms that the SHC dramatically reduces the normal adhesion strength of the ice layer on asphalt pavement. In addition, the microwave heating rate of the asphalt mixture coated with SHC is 48.37 % faster than that of the asphalt mixture without coating. Carbon nanotube particles directly contact the ice on the SHC surface. Besides, carbon nanotube particles also have high microwave heat conversion efficiency and high thermal conductivity. The ice layer on the surface of the asphalt mixture coated with SHC can be melted and removed within 80 sec, which is 42.86 % faster than the ice removal time of asphalt mixture without coating. Carbon nanotube particles on the SHC surface were directly heated by microwaves and melted the ice layer rapidly. The acrylic coating on the asphalt mixture surface has an excellent thermal insulation performance. The load wheel rolling experiment was conducted to simulate the traffic wheel friction. The static contact angle of the water droplet on the SHC keeps at 147°, and the microwave heating performance of the SHC has no significant changes before and after 500 rolling times. This implies that the SHC has sustainable superhydrophobic properties and can melt the ice layer under microwave heating even after the traffic wheel friction. The SHC is of great significance for improving the driving safety of asphalt pavement.
... For liquid water, this movement occurs at GHz (microwave) frequencies, while for ice it occurs at kHz (long radio waves). As a result, microwave heating will not work on ice, but it will work very well on water formed from melting ice [20]. An example of the pavement cross-section is shown in Fig. 3. ...
... Induction heating is the process of heating an electrically conductive element through electromagnetic induction, the operating frequency of which is in the range 1 kHz -1 MHz [20]. Neither snow, ice, nor a standard mixture are such materials. ...
The main aspect of winter maintenance is removing winter slipperiness. The article presents an overview of pavement heating methods that are an alternative to standard methods of dealing with snow and ice. Hydraulic, electric, microwave and induction heating was analyzed. The research and implementation of individual methods were presented. Keywords: Heated pavements; Winter maintenance
... Steel fiber [14,15], carbon fiber [16][17][18][19], and graphite [20,21] are the types of electrically conductive fillers that can render the asphalt mastic electrically conductive. In addition, Sun et al. (2018) investigated the ice and snow melting property of asphalt mixtures infused with steel wool and steel slag [22]. The ice and snow melting performance of the induction heated asphalt mixtures was reported to be remarkable. ...
... Steel fiber [14,15], carbon fiber [16][17][18][19], and graphite [20,21] are the types of electrically conductive fillers that can render the asphalt mastic electrically conductive. In addition, Sun et al. (2018) investigated the ice and snow melting property of asphalt mixtures infused with steel wool and steel slag [22]. The ice and snow melting performance of the induction heated asphalt mixtures was reported to be remarkable. ...
This paper focused on ice processing and snow melting on urban pavement during the winter time in South China under the emergent situation. A kind of electrothermal cushion with carbon fiber was developed to improve resistance to skidding of pavement in winter and help melt ices and snows on the surface of pavement to ensure driving safety. This special cushion is composed of multilayer materials and structures. Laboratory tests for the cushion were conducted to analyze its electrothermal performance, heating uniformity, effect of ice melting, skidding resistance and frictions. At the same time, the durability of the ice melting cushion was evaluated. The results indicate that the developed anti-skidding electrothermal ice melting cushion with carbon fiber is stable in heating ability, high in heating speed, and the surface and bottom temperature of the ice melting mat during operation is not more than 30 ℃ without burning pavements and wheel tires, and the melting rate can reach 78.7% for one hour. The cushion can achieve excellent skid resistance and interlayer friction performance. The cushion can completely meet the requirements such as repeated rolling compaction under vehicle load, abrasion, bursting, etc., and have good durability. Therefore, the cushion is recommended to directly be placed on the pavement surface without interrupting traffics to improve the anti-skidding performance and short-term ice and snow melting in winter. The cushion has lower heating and deicing cost and has a better deicing effect and better economic benefits. Moreover, the cushion only needs to be used in winter, which extends its service life and can be reused without adverse impact on road performance.
... Coatings 2023, 13, 1396 2 of 20 mixtures [12,14]. The first one can melt the ice and snow through a chemical process [15,16], while the second one should be associated with a microwave or an induction-heating machine to melt the ice/snow [17,18]. Superhydrophobic asphalt mixtures can also mitigate this problem [19,20]. ...
A smart asphalt mixture holds new capabilities different from the original ones or can react to a stimulus. These capabilities can be categorized based on smartness or function: smartness, mechanical, electrical, optical, energy harvesting, electromagnetic wave/radiation shielding/absorbing, and water related. The most important capabilities applied to asphalt mixtures are the photocatalytic, self-cleaning, self-healing, superhydrophobic, thermochromic, deicing/anti-icing, and latent heat thermal energy storage abilities. This research deals with a bibliometric review of the peer-reviewed journal articles published on the Scopus database, with the strings of terms related to these capabilities and asphalt or bitum in their titles, abstracts, and keywords. The review analysis highlighted the increasing number of accumulated publications, confirming the relevance of this research topic in recent years. The capability most often referred to was self-healing. The study showed that China was the most productive country. Research articles were mostly published in the journal Construction and Building Materials. Several techniques and methods are being developed regarding smart asphalt mixtures; for that reason, this research work aims to evaluate the literature under a bibliometric analysis.
... Moreover, the pavement condition also affects ride comfort, increases vehicle operating costs, and increases the greenhouse gas emissions associated with road transportation [5][6][7]. Endowing asphalt concrete with highly conductive properties to develop smart pavement, such as self-sensing [8,9], self-deicing and snow-melting [10][11][12], self-healing (or repairing) [13][14][15], and self-harvesting energy pavement [16,17], provides an effective way to develop long-life, sustainable, and low-carbon pavement, as shown in Fig. 1. ...
Endowing asphalt concrete with stable conductive properties is beneficial to develop smart pavement such as self-sensing, self-healing, self-deicing and snow-melting pavement, thus improving the service life and realizing the sustainable development of pavement. In this paper, the conductive properties and mechanisms of high anti-corrosion stainless steel wires (SSWs, with a diameter of 20 μm) and stainless steel fibers (SSFs, with a diameter of 0.2 mm) modified asphalt concrete fabricated by different mixing methods were investigated. Experimental results show that incorporating 1 vol% SSWs firstly with asphalt and mineral powder can reduce the direct current (DC) resistivity of asphalt concrete to 18.54 Ω·m and make alternate current resistivity independent of voltage frequency, while the DC resistivity of asphalt concrete with 24 vol% SSFs (firstly mixing SSFs with aggregates) is still as high as 10⁴–10⁶ Ω·m. The equivalent circuit obtained by electrochemical impedance spectroscopy and the conductivity calculated by general effective media equation illustrates that the conductive elements in SSFs modified asphalt concrete are mostly interface capacitors between SSFs, while low content of SSWs have overlapped to form the stable conductive path in asphalt concrete, resulting from the micro diameter, high aspect ratio, and high flexibility of SSWs.
... Based on the theories, heating asphalt concrete technologies were proposed to heal the crack that occurred in the service process due to ageing, traffic loading, or fatigue. Induction heating and microwave heating are efficient and non-contact heating methods that are suitable for heating asphalt pavement [49]. They just take dozens of seconds to heat up to asphalt's self-healing temperature. ...
Crack healing has been a key area of asphalt pavement research. In this review, different crack-healing theories and crack-healing evaluation methods in bitumen and asphalt mixtures are summarized and presented. Then different crack healing technologies have highlighted the problems and solutions associated with their implementation. Detailly, traditional technologies (hot pouring and fog seal) are introduced. They mainly fill cracks from the outside, which can effectively prevent further damage to the asphalt pavement, when the cracks have generally developed to the middle and late stages of practical engineering. Their extension of the life of the asphalt pavement is relatively limited. Energy supply technologies (induction and microwave heating) have demonstrated significant efficacy in enhancing the crack healing capability of asphalt pavement, particularly in microcracks. Now, Extensive laboratory testing and some field test sections have been conducted and they are waiting for the promotion from the industry. The agents encapsulated technologies (Saturated porous aggregates encapsulate rejuvenators, Core-shell polymeric microcapsules, Ca-alginate capsule, Hollow fibers and Compartment fibers) not only heal cracks but rejuvenate the aged asphalt pavement. In order to promote industrial application, more field test sections and large industrial mixing and compaction equipment applications need to be implemented. Finally, some other potential crack healing techniques (coupling application, electrical conductivity, 3D printing, and modifications) are also mentioned.
... Liu partially replaced the filler in asphalt mixture with ACP and tested the ice melting efficiency, showing that the addition of ACP increased the ice melting efficiency by 2.47 times [16]. Sun added steel slag as aggregates into the asphalt mixture to improve its ice melting performance and proved that the ice melting rate can be increased to 18.5 g/min by adding steel slag [17]. Besides magnetite and steel slag, other microwave-absorbing materials that have been studied include steel fiber, activated carbon powder, graphite and carbon black [18][19][20]. ...
Microwave heating is widely employed in pavement deicing. However, it is difficult to improve the deicing efficiency because only a small part of the microwave energy is used and most of it is wasted. To improve the utilization efficiency of microwave energy and the deicing efficiency, we used silicon carbide (SiC)–replaced aggregates in asphalt mixtures to prepare an ultra-thin, microwave-absorbing wear layer (UML). The SiC particle size, SiC content, oil–stone ratio and thickness of the UML were determined. The effect of the UML on energy saving and material reduction was also evaluated. Results show that only a 10 mm UML was needed to melt a 2 mm ice layer within 52 s at −20 °C and rated power. In addition, the minimum layer thickness to meet the specification requirement (≥2000 με) of asphalt pavement was also 10 mm. SiC with larger particle sizes increased the temperature rise rate but decreased the temperature uniformity, instead increasing the deicing time. The deicing time of a UML with SiC particle size less than 2.36 mm was 35 s shorter than that of a UML with SiC particle size greater than 2.36 mm. Furthermore, more SiC content in the UML resulted in a higher temperature rise rate and less deicing time. The temperature rise rate and deicing time of the UML with 20% SiC were 4.4 times and 44% of those of the control group. When the target void ratio was 6%, the optimum oil–stone ratio of UML was 7.4%, and it had good road performance. Compared to overall heating, the UML saved 75% of power and SiC material under the same heating efficiency. Therefore, the UML reduces microwave deicing time and saves energy and material.
... Asphalt mixture heat-transfer properties have attracted considerable attention among engineers, especially for the repair of asphalt concrete (Pan et al. 2015;Sun et al. 2018). Some researchers have used self-healing methods to repair cracks and increase pavement service life. ...
Due to environmental pollution and the shortage of nonrenewable natural resources in road construction, the use of copper slag as
a new material in asphalt pavement has been recently evaluated for its ability to reduce the accumulation of waste and lower the cost of asphalt mixture production. The main purpose of this study was to assess the feasibility of using copper-slag filler as a substitute for lime in warm-mix asphalt (WMA) to enhance its self-healing and thermal/electrical conductivity potential. To this end, an X-ray fluorescence (XRF) test was first conducted to analyze the copper-slag filler constituent elements that affect its microwave heating. Then, the self-healing potential of asphalt samples containing copper-slag filler under microwave heating was investigated using thermal imaging, and an index was presented to analyze the fracture energy and load-bearing capacity at each stage of the fracture-healing test. Moreover, an image processing technique was used to determine its capability for uniform heat transfer. Finally, some tests were performed to study the asphalt mixture heat-transfer potential and determine its thermal/electrical conductivity. The results show that the mixtures containing copper slag had high thermal/electrical conductivity. Thermal conductivity, microwave heating uniformity, and self-healing potential (asphalt resistance against reloading)
of asphalt mixtures increased with an increase in the copper-slag filler content. With 40, 50, and 60 s of microwave heating, the samples containing copper slag had an average of 14%, 31%, and 37% better recovery, respectively, than the asphalt samples containing 100% of lime filler.
... Functionalization consists of developing a new material capability. Several capabilities have been applied to asphalt mixtures, such as photocatalytic [3,4], superhydrophobic [5][6][7], self-healing [8][9][10], de-icing/antiicing [11,12], self-cleaning [13][14][15], thermochromic [16][17][18], and latent heat thermal energy storage [19][20][21]. These abilities are developed mainly by employing nano/microparticles, phase change materials (PCMs), fibers, and dyes [1]. ...
Asphalt pavements are designed to resist weathering and road traffic while guaranteeing safe and comfortable driving conditions at low cost and with minimal environmental impact [...]
... At present, deicing technologies include conductive concrete [1][2][3], circulating heating systems [4][5][6], electric cable heating [7], solar energy [8], geothermal systems [9,10], induction heating, microwave heating [11], etc. Compared with the above deicing technologies, self-ice-melting asphalt pavements with salt-storage additives have the advantages of relatively low cost and easy construction. ...
Based on laboratory tests, the objective of this study is to assess long-term road performance and to predict deicing longevity of self-ice-melting asphalt pavements containing salt-storage materials. Dry–wet cycles and freeze–thaw cycles were used to treat the specimens at different durations. The long-term road performance of self-ice-melting asphalt mixtures was evaluated by freeze–thaw splitting tests, high-temperature rutting tests, and low-temperature beam bending tests. In addition, the influences of coefficients of void ratio, temperature, vehicle load, crack, and Mafilon (MFL) content on salt precipitation were quantified by conductivity tests, and single consumption of snow and ice melt was quantified by total dissolved solids (TDS) tests. The results show that the long-term water stability, long-term high-temperature stability, and long-term low-temperature crack resistance of self-ice-melting asphalt pavements tended to decrease as the number of dry–wet cycles and freeze–thaw cycles increased. Freeze–thaw cycles exerted deeper influences on the deterioration of road performance than dry–wet cycles, especially on water stability. With increased void ratio and temperature, salt precipitation was accelerated by 1.1 times and 1.5~1.8 times, respectively. Under vehicle loads and cracks, salt precipitation was accelerated by 1.5 times and 1.65 times, respectively. With decreased MFL content, salt precipitation slowed down by 0.54 times. Finally, based on the proportion of each factor relative to the whole life cycle of the pavement, a dicing longevity prediction model was established considering the above factors.
... In this way, the use of microwave energy can repair the microcracks of asphalt pavements, reducing the carbon footprint of the maintenance and repair operations on roads (Trigos et al. 2020). This technique has been also tested in cold regions obtaining promising results as a deicing solution (Sun et al. 2018b;Ding et al. 2018;Gulisano and Gallego 2021). However, there is still a lack of full-scale experiments and field experiences to ensure the viability of this technique (Gulisano and Gallego 2021). ...
... It was found that the deicing velocity of the newly designed ultrathin friction course can reach 10 g/min. Likewise, Sun et al. observed from the laboratory ice/snow melting tests that microwave heating can help gain an average ice and snow melting velocity of 15 g/min and 48.5 g/min, respectively, for the AC-13 steel slag-based asphalt mixture [19]. These numbers demonstrate that the microwave heating of asphalt mixture with the incorporation of steel slag has the capacity to significantly improve the pavement snow/ice melting efficiency. ...
Steel slag is a solid waste which originates frrom the steelmaking industry. Its improper disposal can cause serious environmental pollution and land encroachment. Currently, recycling steel slag as aggregate for asphalt paving has been identified as an emerging sustainable way to promote the secondary reuse of solid waste. However, the functional use of steel slag aggregates still needs further exploration to maximize its utilization efficiency. This study aimed to develop a novel steel slag-based composite phase change aggregate (SS-CPCA) for snow/ice melting of asphalt pavements. Firstly, a binary n-alkane eutectic system was established to determine the binary eutectic composite of PCMs. In combination with the DSC test results, the n-tetradecane and n-octadecane were screened out as the best binary eutectic composite, of which eutectic mass ratio, phase change temperature, and enthalpy were 84.4: 15.6, 2.87 °C, and 179.60 J/g, respectively. The SS-CPCA was then developed by using the coarse steel slag aggregate to adsorb the PCM composite while using the cement mortar as a coating. A type of SMA-13 asphalt mixture was subsequently selected and used for fabricating the SS-CPCA asphalt mixture. Finally, the pavement performance and temperature regulation performance of the SS-CPCA based asphalt mixture were tested and compared with those of the steel slag-based asphalt mixture. The test results indicated that the pavement performance properties of SS-CPCA asphalt mixture satisfied the specification requirements, verifying the feasibility of utilization of the SS-CPCA for asphalt paving. Moreover, it showed that the incorporation of SS-CPCA has the capability to increase the surface temperature of SMA-13 asphalt mixture as high as 3.4 ℃, while extending the cooling time to 780 s when the asphalt mixture surface temperature reaches 0 ℃. These findings demonstrate that the developed SS-CPCA has a promising snow/ice melting performance for asphalt pavements.
... It is crucial to consider in the design of the asphalt mixtures the effect of shape, size, composition, and conductivity of the raw materials besides the final conductive and the mechanical characteristics of asphalt mixtures. The average melting speed of snow for asphalt mixtures with SF and SS using MH achieves 53.9 and 48.5 g/min, respectively [118]. Although both techniques are feasible to provide this capability, the use of fibers is probably more efficient, but the use of SS contributes to recycling materials, and it is eco-friendly. ...
Currently, there is a growing concern with air pollution, the depletion of natural resources, and,
consequently, with the damage imposed on the environment. Asphalt pavements need to be technically
viable from a mechanical point of view, present adequate functional characteristics in terms of comfort
and road safety, be sustainable and at an acceptable cost. In this context, this thesis aims to develop
recycled asphalt mixtures (ecological through the partial replacement of virgin material) and with new
functions through the integration of nano/microparticles for the surface layer of asphalt pavements. The
integration of nano/microparticles provides new capabilities (functionalization) to asphalt mixtures,
namely photocatalytic, superhydrophobic, and self-cleaning with the additional anti-aging effect of asphalt
binders. With the development of the photocatalytic capability, the asphalt mixtures are able to
photodegrade pollutants, and therefore improving the air quality. Regarding the superhydrophobic
capability, the functionalized asphalt mixtures start to repel the water, providing higher road safety,
especially in periods of rain and negative environmental temperature. With the self-cleaning effect, the
functionalized asphalt mixtures are able to clean pollutants, such as dirt particles, oil, and grease, over
their surface, mitigating the decrease of friction due to the presence of these materials over their surface.
Therefore, an extensive bibliographic review was carried out to support this doctoral thesis. Then, the
asphalt mixtures were functionalized using different application methods (volume incorporation,
modification of binder, and spraying coating) and using different materials (TiO2, ZnO, and
Polytetrafluoroethylene). The new properties and their impacts were analyzed from mechanical,
functional, and functionalization point of views. The main conclusions indicate that these materials can
functionalize the asphalt mixtures to provide them with new capabilities, presenting benefits for the
environment, society, economy, and for the performance of the asphalt mixtures.
... Therefore, microwave heating effectively contributes to energy savings and emission reduction [26,27]. Taking the aforementioned advantages, researchers use this method in asphalt pavement industry for recycling [26,30], de-icing [31], and healing purposes [28,29]. It was concluded that heating process by microwave has no substantial effect on rheological and chemical properties of asphalt binder [23,32]. ...
This research investigates feasibility of using electromagnetic-based method to produce reclaimed asphalt pavement (RAP) mixtures. The conventional heating process in dryers of asphalt plants considerably over ages and diminishes mechanical properties of high RAP asphalt mixtures. In addition, the RAP asphalt plants (i.e., parallel flow, counter flow, and double barrel) have critical drawbacks in producing high RAP asphalt mixtures, such as partial activation of asphalt binder in RAP, non-uniform diffusion between virgin binder-rejuvenator-RAP binder, over aging of RAP aggregates, and high fossil fuels consumption, leading to mechanical, environmental, and economic consequences. Recently, the electromagnetic-based approaches (e.g., microwave radiation) were utilized in pavement industry for the diverse applications, including micro-crack healing and de-icing purposes. In this study, the capability of microwave for heating and preparing RAP mixture, containing different WEO amounts as rejuvenator, was investigated. The fracture properties at intermediate and low temperatures and moisture susceptibility of asphalt mixtures comprised of 80 and 100% RAP prepared using electromagnetic radiation were determined and compared against the mixtures made of traditional draft oven. Besides, effect of different WEO contents, as rejuvenator, were investigated. According to the results, heating of RAP aggregates using electromagnetic radiation as well as addition of WEO can remarkably enhance cracking resistance of asphalt mixtures. Moreover, the sustainability aspects of the suggested approach to prepare the RAP mixtures were compared against the conventional method considering energy consumption, equivalent CO2 emission, and cost values. The gray rational analysis (GRA) was conducted to rank the mixtures according to mechanical and sustainability aspects. The results reveal that utilization of electromagnetic radiation in producing high RAP asphalt mixtures can substantially improve sustainability aspects of RAP asphalt mixture.
... However, their inadequacies in terms of efficiency, safety, implementation cost, and impact on public transportation remain evident. Moreover, the salt caused irreversible damages to pavement structures compromising its function and its service life (Chen et al., 2011;Sun et al., 2018) and water quality are also be highly investigated ( Fig. 6(b) and (c)). Many scholars have conducted considerable research in the field of active snow melting. ...
The major contemporary in road pavement engineering is related to the creation of green and sustainable infrastructures, e.g., reduction of environmental impacts, increase in traffic safety, and transportation efficiency, etc. This review presents the recent trends in research and the technical solutions developed so far to address these challenges. After the analysis of research status in the past decades, a novel technology system of eco-friendly pavements is proposed considering two solutions, materials modification and structure improvement. The construction of an eco-friendly pavement can be achieved thanks to several different technologies ensuring permeable, noise-reducing, self-luminous, and exhaust-decomposing properties as well as apporting lower heat absorbing and enhanced anti-/de-icing characteristics. A systematic review of these technologies is presented pivoting on four main aspects: technical principle, material and structural composition, performance evaluation, and engineering application. The current trend in road engineering is combining the pavement infrastructure with various eco-friendly functions, e.g., water permeability, noise reduction, low heat absorption, exhaust gas decomposition, and anti-/de-icing. Finally, the review lists the drawbacks of the existing technologies, including high cost, single function, etc., and depicts the future developing direction and architecture of the next generation of eco-friendly pavements in which the road infrastructure should have more environmentally friendly functions than the existing technology.
... Deicing salt might erode asphalt pavement and shorten its service life [9][10][11]. Artificial deicing and microwave deicing have some disadvantages, such as the lower efficiency and environmental pollution [12,13]. Positive deicing includes elastic pavement method, low freezing point method, thermal method. ...
Snow and ice is one of the main problems affecting road safety in winter. In order to effectively remove the snow and ice of covering the pavement, the deicing property of asphalt mixture pavement containing steel wool fiber was introduced and investigated by electromagnetic induction heating. Based on the deicing mechanism of Faraday’s law of electromagnetic induction and the Joule’s law, the influences factors affecting deicing efficiency, including length and content of steel wool fiber, ice thickness, output current and ambient temperature were analyzed. Meanwhile, the grey correlation entropy analysis and t-test between the average deicing rate and various influencing factors were explored. BP neural network prediction models of predicting change laws of average deicing rate under different influencing factors were established. The results indicate that the average deicing rate of asphalt mixture adding steel wool fiber increases with the increase of length and content of steel wool fiber. The influence degree of each factor for the average deicing rate is in order as follows: steel wool fiber content, steel wool fiber length, output current, ambient temperature and ice thickness. BP neural network has high accuracy in predicting average deicing rate under various influencing factors and the better simulation results. It is of significance to apply the technology of “electromagnetic induction heating & steel wool fiber” to the efficient deicing of asphalt pavement.
... When bitumen reaches temperatures between 50 and 100 • C, it starts acting as a Newtonian fluid, flowing and filling the cracks [11]. Finally, another application of MW heating is the deicing of road surface, whose effectiveness has been demonstrated by several authors [12][13][14][15]. ...
Microwave (MW) heating could contribute to the sustainability of the construction and maintenance of asphalt pavements. The relationship between frequency and the dielectric properties (i.e. loss factor and penetration depth) is crucial for maximising the MW heating efficiency. The paper aims to study the dielectric properties of conventional and electric arc furnace (EAF) slag asphalt mortars. Results showed that the addition of EAF slag enhanced the dielectric response of asphalt mortars. Moreover, a frequency of 5.8 GHz seems to be the best choice for deicing application and assisted-healing of surface layers up to 7 cm.
... Microwave heating technology is a promising technology. e key of effective heating is that microwave heating is a kind of direct energy conversion within the material while heating [48,49]. According to the previous studies, the amount of curing time can be substantially reduced by using microwave curing due to largely concentrated microwave energy [11], and it is very convenient for large-scale commercial application. ...
One of the failure mechanisms associated with asphalt paving layers, especially on steel deck bridges, is large permanent deformation, which adversely affects its long-term performance in service. Thus, epoxy resin was introduced in asphalt paving industry to tackle permanent deformation of asphalt mixtures due to its thermosetting nature. In this review, epoxy resin as a dominant component of the epoxy-asphalt composite system was first considered, followed by a discussion on its curing methods and curing mechanism. Furthermore, the physicochemical property and mechanical performance of epoxy asphalt and epoxy asphalt mixture were thoroughly examined. Crosslink density of epoxy asphalt dictates its viscosity and thus the allowable construction time. Phase separation and dispersion of asphalt particles in the epoxy matrix was observed for epoxy-asphalt composite, and it showed superior elastic behavior and deformation resistance capability when compared with conventional asphalt materials. Furthermore, epoxy asphalt mixture exhibited significantly higher compressive strength, much better rutting resistance, and superior durability and water resistance properties. However, its low-temperature cracking resistance was slightly compromised.
... In the induced heating method, the alternating magnetic field provides the heat required to increase the binder temperature beyond its Newtonian temperature [1,2,[6][7][8]11,40]. Other applications of induction heating of the asphalt concrete are deicing [41,42], and rapid compaction and patching of pavements with potholes [43][44][45]. In all these applications, the temperature is increased through electromagnetic radiation to achieve the temperature required for each application. ...
A numerical framework is proposed to investigate the effect of steel particles on thermo-electromagnetic response of asphalt concrete aggregate blends. To investigate the effect of microstructural properties on induction heating, aggregates were blended with steel particle with various microstructural characteristics (e.g., size, shape, and geometry). Ampere’s, Maxwell-Faraday’s, Guess’s, Ohm’s and Joule’s laws were coupled to the Fourier’s and Newton’s laws to properly capture heat generation and transfer through conduction and convection mechanisms. Experimental studies were conducted by applying electromagnetic fields to aggregate blends containing inductive particles with different microstructural properties. Microstructural representation of the aggregate blends were reconstructed computationally based on the gradation and properties of aggregates and steel particles. Coupled thermo-electromagnetic simulations were conducted to investigate how microstructural properties of inductive particles affect the induction heating of the aggregate blend. Simulation results as compared to experimental measurements confirm the efficiency and accuracy of the coupled thermo-electromagnetic microstructural simulations. The results are used to determine the optimum design that yields the most efficient inductive aggregate blends.
... In order to keep the road smooth and retain driving safety, salt particles are sprayed directly to melt ice and snow [16,17]. In recent years, the selfsnow-melting pavement, which has achieved certain development, can directly solve the problem by adding snow melting and ice suppression materials [18,19]. No matter what way, the existence of salt will bring continuous negative effects to asphalt pavement. ...
This study aims to investigate the performance evolution and mechanism of asphalt under action of chloride salt erosion. Asphalt samples soaked with five different snow melting chloride salt concentrations were taken as the research object. Then, the high-temperature performance, low-temperature performance, temperature sensitivity and asphalt–aggregate adhesion property of asphalt samples were carried out. Additionally, Fourier transform infrared spectroscopy (FTIR) was used to explore the mechanism of chloride salt erosion on asphalt. Test results showed the linear variation relationships of high-temperature performance, low-temperature performance and temperature sensitivity with chloride salt concentrations. The high-temperature performance of asphalt would be improved by chloride snowmelt salt. With the increase in the chloride salt solution concentration, the low-temperature performance of asphalt became worse, and the temperature sensitivity increased. Moreover, after the effect of the chloride salt solution, the asphalt–aggregate adhesion property decreased with the increase in the chloride salt solution concentration. It is necessary to control the amount of chloride snowmelt salt in the actual snow removal projects. Finally, based on Fourier transform infrared spectroscopy, the mechanism of chloride salt erosion on asphalt was preliminarily explored. With the increase in the chloride salt solution concentration, the proportion of light components (saturated fraction, aromatic fraction) in asphalt decreased, and the proportion of heavy components (resin and asphaltene) with good thermal stability increased.
... Liu et al. (2019a) mixed different types and contents of fibers into asphalt mixture, and studied their induction heating characteristics and fatigue damage self-healing properties in detail. Sun et al. (2018) comparatively studied the effects of induction heating and microwave heating on the melting of snow and ice on asphalt pavement, and proposed heating methods for induction heating to promote the self-healing of pavement cracks when the pavement has ice and snow. ...
As a high-efficiency non-contact heating technology, induction heating has shown great application prospect in melting snow and de-icing of asphalt pavement and induced self-healing of damage of asphalt mixture. In this research, 4 lengths of steel fiber and three fiber contents were adopted. The effect of different lengths and contents of steel fiber on the performances, including optimum asphalt content, high-temperature rutting resistance, low-temperature cracking resistance, freeze–thaw cycles resistance and thermal conductivity (TC), of asphalt mixture were studied in detail. Moreover, the induction heating rates (HRs) of asphalt mixture with different lengths and contents have also been investigated. Finally, the overall performances of asphalt mixture with different lengths of fiber were compared and analysed based on the radar chart method. The results show that when the length is 7 mm and the content is 4% of steel fiber, the optimum asphalt content, TC and HR of asphalt mixture were significantly improved. When the length is 5 mm and the content is 4% of steel fiber, the high-temperature rutting resistance, low-temperature cracking resistance and freeze–thaw cycles resistance were also significantly improved. The radar chart shows that the overall performances of asphalt mixture with 5 mm steel fiber are the best one.
Electrically conductive asphalt concrete (ECAC) is an innovative material that offers numerous possibilities by directly incorporating functional additives (such as metal-based or carbon-based materials) into asphalt binder and mixing it with traditional aggregates and mineral filler. With such a strategy, ECAC possesses a high elec-trical/thermal conductivity, making it an ideal candidate for sustainable repair methods based on induced heating-healing, snow and ice melting systems on pavements, and piezoresistive sensors for traffic detection in pavement engineering. This paper aims to provide a systematic review of the design and development of ECAC, with a particular focus on the advancements made over the past decade (from 2013 to 2023). The review begins by introducing the composition and fundamental principles underlying ECAC. Subsequently, it summarizes the key aspects related to the design and preparation of ECAC. Moreover, this paper delves into the remarkable multi-functionality exhibited by ECAC, showcasing its potential in practical applications. Through examining various case studies, the review highlights the successful utilization of ECAC in diverse scenarios. This review work can serve as a valuable resource, offering insights and guidance for developing ECAC in the context of smart and sustainable pavement construction.
In this article, the 166TYHB road microwave maintenance vehicle was used as the main equipment, aiming at the investigation of the application characteristics of microwave healing technology on asphalt pavement and proving the effective of microwave heating technology in practice. The heating performance and healing behavior of steel fiber modified asphalt pavement under microwave irradiation were analyzed. The maintenance technology of asphalt pavement was designed and optimized, and the corresponding relationship between the maintenance effect of 800 W microwave oven in the laboratory test and the maintenance effect of 90 kW road maintenance vehicle in practical construction was established. The test results showed that with the curing of microwave irradiation, the steel fiber modified asphalt pavement presented an excellent healing performance, and the heating rate of the surface of asphalt pavement could reach as high as 26 °C/min. Meanwhile, as there is no need to apply another raw materials during the maintenance stage, the Pavement Condition Index(PCI) of asphalt pavement could be improved to a high degree, which is much beneficial to maintain the comfortability of pavement.
Snow and sudden heavy fog on the road are significant factors that contribute to traffic congestion and frequent accidents. In light of a number of environmental, economic, and road corrosion problems caused by road snow melting and fog elimination, this work studies a graphene heating film coupled concrete road snow melting and defogging system, which is critical to the transportation safety and economic and social benefits. The graphene heating film is embedded in the road and electrified as a heat source to analyze its function and effect in the process of melting snow and defogging. Furthermore, the heating performance of the various heating elements is compared and analyzed, and the working temperature, spacing, and buried depth of the graphene heating film is investigated. The rationality and efficiency of the graphene heating film coupling concrete road snow melting and defogging system are verified through experimental and simulation analyses.
Microwave heating is considered to be an effective method for accelerating the healing of the asphalt mixture with cracks that contain microwave-absorbing materials. Three fibers as microwave-absorbing materials (i.e., carbon fiber, steel fiber and steel wool) were used to fabricate self-healing asphalt mixtures, and their mechanical properties and self-healing ability were evaluated by semi-circular bending test. Effect of freeze–thaw cycles on the mechanical properties and healing effect of fiber modified asphalt mixtures were investigated, and the different fiber reinforcing effects were studied by the digital image correlation. Results show that although the addition of fibers can greatly improve the mechanical properties and healing ability of mixtures, freeze–thaw cycles have great adverse effects on these performances. Among the three fibers, steel fiber has the strongest reinforcement effect on the fracture behavior of asphalt mixture, and its reinforcement effect and healing ability are also less affected by moisture and freeze–thaw effect than that of steel wool and carbon fiber. Carbon fiber modified asphalt mixture has the lowest fracture and freeze–thaw resistance. Considering the harmful impacts of freeze–thaw cycles and the beneficial impacts of fiber reinforcing effect, steel fiber is recommended for fabricating self-healing asphalt mixture.
The research aims at the preparation and characterization of a functional porous ultra-thin friction course (PUFC) with recycled steel slag as aggregate. At first, the PUFC was designed by modified Bailey method and Particle interference theory, and selected through the TOPSIS (Technique for Order Preference by Similarity to an Ideal Solution) method with index of weight. Then the resistance to dynamic water damage of PUFC was characterized by MIST (Moisture Induced Sensitivity Tester). Meanwhile, the SWMM software was used to simulate drainage performance of PUFC under different rainstorm intensities in Wuhan. Finally, the induction heating efficiency, self-healing property and snow and ice melting property of PUFC with steel wool fibers were investigated. The results demonstrate the PUFC gradation with pores ratio of 21.2% presents the best durability performance. The factors of cycles, temperature, and pressure during the dynamic water damage processing will conduct the weaken impact on the mechanics of PUFC, particularly the temperature. It is also found that the PUFC has the capacity to reduce the runoff, but there is a limitation to this reduction which is 10a of the return period. Furthermore, PUFC with steel wool fibers can be inductively heated, which helps to heal the cracks inside PUFC meanwhile also melt the ice and snow on the surface. Thus, the PUFC can be effectively prepared and its performance of self-healing, drainage, and snow and ice melting contribute its applicability in sponge city engineering.
Heated pavements can be an effective method melt snow and ice on location where traditional snow plowing device is not practical or feasible. However, the energy use during operation limits the application of the technology. Desired innovations to further optimize the operational energy use may be stimulated by a sound understanding of the magnitude of the involved heat fluxes. In this study estimated these heat fluxes in a laboratory set-up and placed in a large walk-in cold room. Snow was melted on a heated asphalt concrete specimen at an air temperature of −5 °C. The inclination angle of the specimen was varied between 0°, 2° and 4° to vary the run-off of meltwater. The melting time, drying time, run-off and energy consumption was recorded and the different heat fluxes were quantified. It was found that the snow melting time did not vary much between the different inclination angles. However, increased the inclination angle from 0° to 2° and 4° reduced the drying time decreased by 30% and 47%, respectively. In resulting total energy use was reduced by 34% and 49%, respectively. The energy reduction was mainly contributed by using less energy for evaporation of meltwater, which was at 0° the dominating heat flux. Although the relative contributions of the heat fluxes can vary between our study and different real-life snow melting systems, this laboratory study illustrates the importance of effective run-off to maximize the efficiency of heated pavements. Several innovative approaches to minimize the evaporative heat losses are discussed.
Induction heating technology has been widely used in the induction healing of dense-graded asphalt pavement (DGAP). It’s realized by heating the inductive materials under the electromagnetic field. The induced healing efficiency is related to the effective induction heating depth (EIHD) of inductive materials. Nevertheless, In the existing studies, the EIHD was defined by the temperature method, which is inaccurate and sensitive. Also, the relationship between EIHD and the induced healing efficiency of DGAP has not been investigated. Therefore, in this study, the heat generation and heat conduction processes of DGAP internal material were analyzed, and the EIHD was defined as the main heat generation area of inductive materials. After establishing the 2-D induction heating model of DGAP, to determine EIHD, the thermal energy of different materials in DGAP was calculated in layers by temperature measurements based on meshing. Additionally, induction heating experiments were conducted to verify the correctness of the method. At last, the relationship between EIHD and the induced healing efficiency of DGAP was found by induction healing tests. The results show that the energy-based calculative method is more accurate than the traditional temperature method. Besides, the relationship between EIHD and the overall average healing ratios of DGAP is accorded with a positive linear correlation, and the gradient healing alleviates with the increase of EIHD. This paper proposes a calculative method of EIHD in DGAP and reveals the relationship between EIHD and induced healing behaviors, which can promote the development of pavement maintenance technology.
The chemical deicing method and the conventional asphalt pavement deicing method by microwave have low efficiency, large construction pollution, and serious energy waste. This paper proposes an eco-friendly microwave deicing method based on the heat generation of the pavement's upper surface. In order to achieve the effect of heat generation on pavement's upper surface, four kinds of waste materials were selected to be mixed with asphalt mixture for experiments. Among these experiments, the temperature field distribution coefficient N was proposed to judge the appropriate types of admixtures, and the ice layer-pavement separation coefficient E was proposed to determine the admixtures' optimum content. Meanwhile, the effect of the heating equipment's moving speed on deicing and snow-melting was studied. Finally, a case study demonstrates this method has the effect of improving deicing efficiency, and comprehensive environmental assessments demonstrate this method has the effects of energy-saving and emission reduction. The results show that waste steel wool is the appropriate type of admixture for microwave deicing and snow-melting. The optimum waste steel wool content is 6%(by asphalt's volume). In addition, emissions are reduced by 5.32 kg in a unit of pavement (2 km long,7.5 m wide with 2 cm thickness of ice layer). The deicing speed can reach 9.7 km/h (36 kW). While improving the operating speed, the method protects the environment and also saves energy.
With the use of nanocomposite synthesis operations, the produced zinc oxide/expanded vermiculite (ZnO/EVMT) composite, a combination of ZnO particles and EVMT, has ZnO particles of the weakened agglomeration effects and can comprehensively improve the resistance of asphalt to thermo-oxidative and ultraviolet (UV) aging. However, the effects of different carriers for ZnO particles on the microstructure of ZnO/layered silicate composite and aging resistance of the composite modified asphalt are still unknown. In this research, three ZnO carriers, montmorillonite (MMT), expanded vermiculite (EVMT) and rectorite (REC), were employed to support ZnO particles (named ZnO/MMT, ZnO/EVMT and ZnO/REC, respectively). Then, the microstructure of different ZnO/layered silicate composites was investigated by field emission scanning microscope (FESEM), X-ray diffractometer (XRD) and UV–visible spectrometer (UV–vis) tests. Finally, the effects of different carriers on the morphology, phase structure, storage stability, physical properties and aging resistance of ZnO/layered silicate composite modified asphalt were discussed. Results showed that with the unique layered structure and its integrity, the three carriers are feasible to synthesize ZnO/layered silicate composite, and ZnO particles are supported or embedded on the surface of layered silicate sheets and have weaker agglomeration effects. Except for ZnO/MMT composite, the other two composites have sufficient composition connection strength. The exfoliated phase structure is formed in the ZnO/MMT or ZnO/EVMT composite modified asphalt systems. Additionally, the three ZnO/layered silicate composites have good asphalt compatibility and storage stability in asphalt, especially for ZnO/REC composite. The addition of ZnO/layered silicate composites into asphalt slightly influences physical properties of asphalt. Incorporating ZnO/layered silicate composites, regardless of the types, into asphalt could comprehensively enhance the resistance of asphalt to thermo-oxidative and UV aging. Comparatively, EVMT and REC are preferable to support ZnO particles and generate ZnO/layered silicate composite and comprehensively improve the aging resistance of asphalt.
Preparations for the Beijing Winter Olympics have promoted the rapid development of ice-snow tourism in China, which contributes to achieving the goal of having 300 million people participate in ice-snow sports. This paper analyzes the status quo and problems associated with the growth of ice-snow tourism in China based on the methods of documentation and field investigation. The results indicate that China's efforts have born abundant fruits. Notwithstanding, there are still some problems due to the limited time and hastened process of ice-snow tourism development, including unreasonable exploitation, low-quality products and services, imperfect investment and financing system, inadequate management, a single marketing mode, and insufficient talent teams. Compared with developed countries in Europe and the United States, ice-snow tourism in China is in the stage of rapid development. To achieve the high-quality development of ice-snow tourism in China, this paper proposes actions from eight aspects which involve policy, products and services, marketing, safety management and control, talent teams, standardization construction, science and technology, and community participation. This study can provide references for the high-quality development of ice-snow tourism in China, as well as perfecting Chinese theoretical research on ice-snow tourism.
In order to prevent snow accumulation and ice formation on asphalt concrete roads, the use of a hydronic heating system embedded in the pavement is recommended as an alternative to traditional snow and ice fighting applications. Hydronic heating systems circulate a heated liquid through a pipe network placed under the pavement layer to melt the snow and ice accumulated in the pavement layer, thus preventing the road surface from icing. Various parameters need to be evaluated for a reliable and economically viable hydronic snowmelt system. In this study, the stresses that occur as a result of traffic load in flexible pavements where hydronic heating systems are used and the stresses that occur as a result of traffic load in flexible pavements without hydronic heating system are compared using finite element software. Evaluations were made using five different air temperatures and three different inlet water temperatures. In the study, the stresses occurring in the surface course were investigated when buried pipes are located in the surface course, binder course, asphalt base course and gravel base layer. In addition, the stresses that occur as a result of traffic load in pe-x pipes used in the system were also evaluated.
By synthesizing zinc oxide/expanded vermiculite (ZnO/EVMT) with a modified hydrolytic precipitation method, the composite could remarkably strengthen the resistance of bitumen to thermo-oxidative and ultraviolet (UV) aging. Nonetheless, the microstructure of the composite synthesized using different methods and their effects on microstructure and aging resistance of bitumen have been insufficiently researched. Thus, a modified sol–gel (SG) method and the hydrolytic precipitation (HP) method were used to produce ZnO/EVMT composite (remarked as SG-ZnO/EVMT and HP-ZnO/EVMT respectively) in this study. Then, the effects of two synthesis methods on the microstructure of ZnO/EVMT composite and its corresponding modified bitumen were characterized with a series of experiments, including X-ray diffractometer (XRD), field emission scanning microscopy (FESEM), Fourier transform infrared spectrometer (FTIR) and ultraviolet–visible spectrometer (UV–Vis) tests. Finally, the resistance of the two ZnO/EVMT composite modified bitumen to short-term aging, long-term UV aging and long-term thermo-oxidative aging was evaluated with softening point increment and viscosity aging index. Results indicated that the two methods are feasible to synthesize ZnO/EVMT composite, and ZnO particles in HP-ZnO/EVMT have higher crystallinity and purity with the HP method. Furthermore, HP-ZnO/EVMT has a more homogeneous distribution of ZnO particles, higher UV absorption capacity and better bituminous compatibility than SG-ZnO/EVMT. With the addition of the SG-ZnO/EVMT or HP-ZnO/EVMT into bitumen, intercalated phase structures are formed in the corresponding modified bitumen. Additionally, the ZnO particle composition completely separated with EVMT composition in the SG-ZnO/EVMT modified bitumen, but HP-ZnO/EVMT composite in its corresponding modified bitumen still maintained the original characteristics. Based on the above, bitumen modified by HP-ZnO/EVMT has stronger aging resistance than that of SG-ZnO/EVMT regardless of the aging conditions. Therefore, the HP method is recommended to synthesize ZnO/EVMT composite for bitumen modification.
Hot in-place recycling (HIR) has been adopted in pavement engineering because of its low financial cost and lower consumption of nonrenewable material. At present, infrared heating is the most common heating method in HIR, while microwave heating has been proposed as an alternative to it recently. This study investigated and compared the characteristics of microwave and infrared heating by laboratory experiments and numerical modeling. Laboratory tests were first conducted to determine thermal parameters of asphalt mixture and calibrate electromagnetic parameters based on numerical simulation. Two numerical models of microwave and infrared heating under field conditions were further established for analyzing the heating characteristics, including the temperature distribution, heat transfer rate, and energy consumption. The results show that infrared heating can only heat the pavement at shallow depth, while microwave heating can heat the pavement surface and the materials at greater depths to high temperatures. An increase in power was found to enhance the efficiency of microwave heating but to maybe reduce that of infrared heating. Moreover, under the same power, microwave heating needs much less time and energy than infrared heating to reach the same temperature. Microwave heating shows great potential to be applied for HIR of asphalt pavement with the increased recycling depth.
The purpose of this study is to explore the influence of oil-milled bentonite on the aging behavior and mechanical properties of modified asphalt binders. In this paper, bentonite (BT) was used as the raw material, and waste engine oil (WEO) was used as the grinding medium. The nano-bentonite (OBT) was prepared through the liquid phase ball milling process. Liquid phase mechanical grinding and organic activation of bentonite with waste engine oil mixed with asphalt to modify asphalt. Through X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and surface area analysis (BET) was operated to study the structure and properties of nano-bentonite. The results showed that WEO successfully entered the interlayers of OBT, and the layer spacing was significantly enlarged. Through thin film oven test (TFOT), pressure aging test (PAV), nanoindentation, and universal testing machine experiments (UTM), the aging behavior and mechanical properties of nano-bentonite modified asphalt were tested. From the results, the introduction of OBT into asphalt significantly improved the surface anti-aging behavior of asphalt. The results of Fourier Infrared Spectroscopy show that WEO and the exfoliated OBT in modified asphalt could effectively delay the surface aging behavior of asphalt. The data of nanoindentation and UTM showed that OBT had the potential to optimize the low-temperature resistance of modified asphalt. The work provided a new method for solving the aging of asphalt materials and promoting nano-material modified asphalt, which had good prospects.
Automatic induction self–healing treatment (AI–SHT) is a novel maintenance method for asphalt pavements that can efficiently heal cracks when inductive particles are incorporated into the asphalt. In the case of asphalt pavements on steel bridge decks, the metallic elements of the bridge act as the inductive materials to heal the cracks. This study focused on verifying the engineering feasibility and economic value of using AI–SHT for steel deck asphalt pavement (SDAP). The magnetic circuit principle was introduced to explore the self–healing effects. Fracture and induction self–healing tests were conducted based on a simplified model of the SDAP. Results showed that the maximum strength recovery rate via intermittent heating, without considering the aging, could reach 89.5%, which almost returned the strength of the newly constructed SDAP. Meanwhile, the maintenance cost of the AI–SHT could be ignored compared with the conventional maintenance method.
Self-healing roads are a new generation of pavements whose materials are capable of recovering their original properties after having suffered breakages or failures. This innovative technology aims to reduce the consumption of natural resources and non-renewable energy in the whole life-cycle of roads, due to the potential achievement of increasing their lifespan compared to traditional maintenance operations. Several previous tests have demonstrated the possibility of achieving new asphalt mixtures that could be self-healing by means of microwaves or induction when the pavement reaches deterioration, so the traditional maintenance technique could be postponed. As self-healing technology is still under study, there is a lack of rigorous environmental and economic studies. This study presents the quantification of the advantages and shortcomings of this novel technique when compared to traditional rehabilitation activities, since it is currently one of the priority research lines for paving materials nowadays. Analyses have been done by the application of the Life Cycle Assessment methodology. Results show a clear influence of self-healing in the comparative environmental performance in the majority of the impact categories. In fact, climate change impact could be reduced up to 15%, while the acquisition of extra abiotic materials is reduced by 50%.
Electrically heated roads are used as a substitute for chemicals and mechanical devices to ensure mobility and traffic safety in winter weather. This paper aims to design an electrical-thermal system and recommends the best system parameters based on the melting efficiency, energy costs and mechanical durability of the pavement. In addition, the snow melting effect was verified experimentally according to the recommended parameters and the accuracy of the electrical-thermal system was predicted and evaluated by back-propagation neural network. Experiment results indicate that the 24 K Teflon‑carbon fiber heating wire is suitable for the road heating system. It can provide a stable heat source and has the characteristics of high temperature/pressure resistance during the asphalt mixture molding and rolling process. The system parameters were recommended based on snow melting efficiency and mechanical durability of the pavement such as temperature stress and temperature uniformity. The optimal heating wire spacing is 10 cm, set heating wire depth as 4 cm, besides, the heating wire power can be determined based on energy consumption, and actual environmental conditions. The recommended parameters were used for snow melting laboratory experiments to verify the validity of the electrical-thermal system. Finally, the temperature trend of this system can be predicted and evaluated well with high accuracy by the back-propagation neural network. The research enriches the theory of thermodynamic structural design for snow melting pavement systems.
Self-healing asphalt pavements are an alternative and sustainable road infrastructure. Through a literature review and laboratory tests, the authors aimed to develop a methodology to study the efficiency of asphalt pavement self-healing techniques. Results showed that Healing Indexes based on peak loads could be misleading to estimate the effectiveness of self-healing techniques. A novel methodology using the semicircular bending test and the fracture mechanics parameter Jc is proposed to estimate pavement fatigue life extension when self-healing techniques are applied. Following this novel methodology, results show that one cycle of microwave heating of conventional asphalt pavement achieves a 20% fatigue life extension.
Road pavements are designed to withstand road traffic and weathering actions while ensuring comfortable and safe riding conditions as well as low costs and damage to the environment. When a road pavement has additional abilities or reacts to an external stimulus, it is considered to be smart and multifunctional. Examples of such abilities that have been investigated in asphalt mixtures are photocatalytic, superhydrophobic, self-cleaning, de-icing/anti-icing, self-healing, thermochromic, and latent heat thermal energy storage abilities. These abilities are developed using different materials such as nano/microparticles (including semiconductor materials and microcapsules), fibers, phase change materials (PCMs), and dyes, often using dissimilar techniques such as spray coating, volume incorporation, spreading, and asphalt binder modification. Owing to their large surface areas, road pavements are true recipients for large amounts of nano/micromaterials, and consequently, act as important “tools” to stimulate an emerging sector related to the scale of production of materials in the form of nanoparticles. Moreover, smart and multifunctional road pavements can be included in the domain of clean technology (e.g., photocatalytic pavements that promote the environmental depollution of NOx-type gases emitted as vehicle exhaust gases). In this context, they can contribute to materializing the transition to a novel socio-economic model known as “Green Recovery” that is environmentally friendly, sustainable, and inclusive. This model is a very important path toward economic and employment recovery, a vision to which many countries are strongly committed. Therefore, this work reviews new capabilities imparted to asphalt mixtures and provides recommendations.
Induced heating-healing of asphalt concrete is rapidly emerging as an innovative repairing technique in pavement engineering. In this method, asphalt concrete is heated using the external electromagnetic field. As a result, the viscosity of the asphalt binder decreases, leading to the movement of the asphalt binder through the cracks and healing them. Researchers have been intensively investigating this technique as a potential practical method to heal the cracks and extend the service life of asphalt concrete and pavement. This review paper itemizes the applications of induced heating in pavement engineering. The induced healing, as the predominant application, was compared against the self-healing mechanism in asphalt concrete. Different types of heating sources and their effects on induced heating-healing of asphalt concrete were investigated. Different types of conductive additives (i.e., fiber, powder, and granular) are utilized to enhance the induced heating-healing efficiency. This study covers the influence of conductive additive type on the rate of induced heating-healing, thermal conductivity, heat transfer, temperature distributions, and mechanical characteristics of asphalt concrete. Besides, the effects of different parameters (i.e., mixture components, aggregate gradation and type, specimen dimension, breaking temperature, crack configuration, mechanical damage, aging, moisture/freeze-thaw damage) on the induced heating-healing process in asphalt concrete were introduced and discussed in detail. Afterward, the sustainability aspects of the induced heating-healing technique (i.e., cost, greenhouse gas emission, and energy consumption) were investigated and compared with existing asphalt concrete repairing methods. Finally, the existing challenges regarding the induced heating-healing technique and suggestions for future studies were presented.
Studies have shown that the sustainable self-healing ability of asphalt materials under microwave radiation is related to the microwave absorption of the constituent materials. As a typical absorbing material, Fe3O4 and its derivatives have the potential to heal the micro cracks of asphalt materials multiple times by themselves, and enhance the sustainable self-healing properties. However, former researchers have neglected the fact that Fe3O4 will be gradually oxidized at high temperatures, such as 100 °C, resulting in the changes in material properties, microwave absorption and heat-generating capability. Therefore, the effects of different temperatures on the properties of controllable synthesized Fe3O4 were studied at 125 °C (mixing temperature of WMA), 150 °C (mixing temperature of HMA), 175 °C (mixing temperature of HMA with modified binder) and 200 °C (extreme mixing temperature). The phase compositions, chemical structure of synthesized Fe3O4 were characterized firstly. Then, their electromagnetic parameters, reflection loss were studied at a microwave frequency ranging from 1 to 18 GHz. Additionally, heat-generating abilities of them were characterized at usual microwave frequency of 2.45 GHz. Finally, the effects of different content of Fe3O4 on the rheological properties of pure asphalt were studied. The results show that the proportion of γ-Fe2O3 in the samples gradually increase with exposure temperature, and the static magnetic properties gradually deteriorate. The reflection loss of the modified asphalt decreases firstly and then increases. The F-150 modified asphalt has the strongest microwave absorption capacity. Under the 2.45 GHz microwave radiation, the F-150 modified asphalt presents the strongest heat-generating capability and is consistent with the results of reflection loss. It can be seen that the ratio of γ-Fe2O3 and Fe3O4 in F-150 has the best attenuation effect on microwave radiation, and Fe3O4 is more suitable as microwave absorber for self-healing enhancement of HMA.
Self-healing technology is a new field within material technology. It represents a revolution in materials engineering and is changing the way that materials behave. Incorporating self-healing technology into the road design process has the potential to transform road construction and maintenance processes by increasing the lifespan of roads and eliminating the need for road maintenance. By decreasing the unnecessary premature ageing of asphalt pavements, self-healing asphalt can reduce the amount of natural resources used to maintain road networks, decrease the traffic disruption caused by road maintenance processes, decrease CO2 emissions during the road maintenance process and increase road safety. In addition to environmental savings, self-healing materials have the potential to deliver significant cost savings for road network maintenance across the EU. There are three main self-healing technologies available for asphalt pavement design: nanoparticles, induction heating and rejuvenation. This chapter reviews all three options and outlines the future development of self-healing asphalt technology.
This paper summarizes the main results of experimental research on the induction healing of dense asphalt concrete with steel wool fibers. Different physical properties of dense asphalt concrete, as the steel wool fibers distribution, mechanical properties, thermal conductivity, and healing via induction heating have been analysed. The main results show that short and thick fibers disperse very well in the mixture, while long and thin fibers produce clusters. It was also observed that fibers can be damaged during the mixing and compaction processes. In addition, it was found that steel wool fibers do not significantly improve the mechanical properties and damage resistance of dense asphalt concrete. Moreover, steel wool fibers slightly increase the thermal conductivity of dense asphalt concrete. Furthermore, the temperature reached due to induction heating increases with the number of fibers in the mixture and with their diameter. Finally, it was found that dense asphalt concrete heals through the increase of temperature and that the type and diameter of fibers do not influence the healing properties of dense asphalt concrete.
A comparison of structure and dielectric properties of TlSbS2 thin films, deposited in different thicknesses (400–4100 Å) by thermal evaporation of TlSbS2 crystals that were grown by the Stockbarger–Bridgman technique and the bulk material properties of TlSbS2 are presented. Dielectric constant ε
1 and dielectric loss ε
2 have been calculated by measuring capacitance and dielectric loss factor in the frequency range 20 Hz–10 KHz and in the temperature range 273–433 K. It is observed that at 1 kHz frequency and 293 K temperature the dielectric constant of TlSbS2 thin films is ε
1=1.8–6 and the dielectric loss of TlSbS2 thin films is ε
2=0.5–3 depending on film thickness. In the given intervals, both of dielectric constant and dielectric loss decrease with frequency, but increase with temperature. The maximum barrier height W
m is calculated from the dielectric measurements. The values of W
m for TlSbS2 films and bulk are obtained as 0.56 eV and 0.62 eV at room temperature, respectively. The obtained values agree with those proposed by the theory of hopping over the potential barrier. The temperature variation of ac conductivity can be reasonably interpreted in terms of the correlated barrier hopping model since it obeys the ω
s
law with a temperature dependent s (s<1) and going down as the temperature is increased. The temperature coefficient of capacitance (TCC) and permittivity (TCP) are evaluated for both thin films and bulk material of TlSbS2.
It is well known that the healing rates of asphalt courses increase with the temperature. A new method, induction heating, is used in this paper to increase the lifetime of asphalt concrete pavements. Mastic will be first made electrically conductive by the addition of conductive fibers. Then it will be heated via induction energy. This will repair the damage in the pavement, closing the cracks that could have appeared during its lifetime. Adding too much heat will melt the binder completely and the properties of the material will be lost. In the paper it is shown how this method can be repeated many times for samples that are completely broken and that the evolution of the mechanical resistance of specimens that are broken is limited. It will also be shown how the chemical properties of the bitumen do not change due to heating.
In this paper, two different designs of self-healing asphalt mixtures were promoted, the asphalt mixtures were healed through heating fibers or aggregate respectively. Induction heating and microwave heating were applied respectively to provide healing atmospheres. The thermal conductivity and temperature raising tests were conducted to measure the heating performance of those two self-healing asphalt mixtures. Infrared images were used to demonstrate the temperature field of asphalt specimens during heating. Cyclic fracture-healing test with three-point bending method was recorded to investigate the healing performance of the designed asphalt mixtures.
Microwave treatment of asphalt mixtures is believed to have the potential of improving asphalt adhesion to aggregate. Presented in this paper is the work that was carried out to investigate this aspect of microwave heating in two ways. First, possible mechanisms by which adhesion improvement may occur when mixtures are exposed to microwave energy are discussed. Second, results of resilient modulus and split tension tests conducted on mixtures that were prepared in the laboratory using a convection oven and a kitchen-type microwave oven are reported. The study involved preparing three groups of mixtures: plan, virgin with an antistripping additive, and artificially aged materials. Test results indicate that microwave energy treatment of asphalt mixtures improves their adhesion and their resistance to water damage.
As one of the major distresses of asphalt pavement, the moisture damage usually results in a very serious loss of strength and structural deformation. This paper aimed to study the healing properties of asphalt concrete suffered moisture damage. Both microwave heating and induction heating were applied in this research to activate healing. A series of experiments including freeze-thaw splitting test, Marshall Immersion test and three-point bending test were conducted to evaluate the healing performance of asphalt concrete. It was found that the heating speed of asphalt mixtures was enhanced at the presence of water. The results also indicated that both microwave heating and induction heating could only partially heal the loss of strength of asphalt mixtures suffered moisture damage due to structural deformation of the samples, which could not be healed with heating technics. The presence of moisture significantly decreased the healing rate of asphalt mixtures induced by induction heating or microwave heating. It was believed that the moisture on crack surfaces could prevent the thermal healing of cracks. It is recommended that the asphalt mixtures be healed in dry condition rather than at the presence of water.
This paper aims to evaluate the effect of microwave and induction heating on the self-healing of asphalt mixture test samples. With this purpose, dense asphalt mixtures with four different percentages of steel wool fibres have been prepared to build semi-circular asphalt test samples. Asphalt self-healing has been characterised as the three-point bending strength of test samples before and after healing. This process was repeated ten times in every test sample. Moreover, self-healing was induced in the semi-circular test samples by heating them under microwave and induction. Besides, the chemical degradation of asphalt mixture under microwave and induction heating was monitored by measuring the mass of test samples before and after the heating process. It was found that microwave technology is more effective than induction heating to heal cracks in asphalt roads. Furthermore, the healing level of asphalt mixtures reduced with every healing cycle, until the test specimens could not resist more damage-healing cycles. It could be seen that microwave heating degrades bitumen, and increases the porosity of asphalt mixture. Finally, it was hypothesised that air voids in mixture play an important role in asphalt self-healing by increasing the internal pressure and mobility of bitumen during the heating process.
Solar energy is undoubtedly the environment friendly and inexhaustible energy resource for humans. The concept of hydronic asphalt pavement (HAP) is an emerging renewable energy technology, which provides an interesting method for solar energy utilization. The innovation of HAP is to mitigate a series of realistic problems related to the asphalt pavement as well as the depletion of fossil energy resource. Fluid circulating through the pipes network imbedded in the asphalt pavement can capture the solar energy and store for later use. This paper summaries the major achievements of the existing literatures about the HAP and gives some proposals for further investigations. Studies have confirmed the feasibility of harvesting solar energy, cooling the pavement, snow melting/deicing as well as air conditioning of buildings by applying innovation technologies on asphalt pavement. As seasonal energy storage technology is relatively mature at present, most of the literatures reviews focus on the influences of variables associated with system behavior as well as the heat transfer processes during snow melting and solar energy collection. Future work should aim to do more urgent issues involved with HAP application: construction technology, maintenance technology, and long-term performance. Solving these problems can strengthen the theoretical and practical understanding of HAP, and lead to more extensive applications.
The measurement of dielectric properties of materials is critical to understanding the electromagnetic field distribution in the materials. Reliable knowledge of the dielectric constant is also important when designing a microwave pyrolysis unit for effective pyrolysis of materials of interest. The dielectric probe technique was used to evaluate the dielectric properties of biosolids. Biosolid samples were collected from various sources and the dielectric properties were measured across the microwave frequency range of 1.0 GHz to 10.0 GHz. The dielectric constant of the materials varied in the range from 80 to 2 and depended mainly on the origin of the sample, the electrical conductivity and the moisture content of the material. A mathematical model was developed to accurately predict the values of complex permittivity. This model was verified using the measured data.
Light rail transit (LRT) vehicles that employ electric power supply systems along the running rails may be forced to suspend operations when snow or ice freezes on the collector shoe. The presence of snow on the collector shoe causes loss of power supply to the train unless the power supply system has a melting system with sufficient heating capacity to melt the snow. A general solution to prevent ice formation on railroad systems is to preliminarily operate a heating system in the running rail and guide rail based on weather forecasts. However, excessive pre-heating increases electricity costs and reduces the durability of the concrete running rail by subjecting it to persistent thermal stresses, which in turn leads to increased maintenance costs.
To minimize electric power consumption and maintain stable train operations, a reliable standard for the operation time of the electric pre-heating system must be established. In this study, we analyzed the operational conditions and impact of snow melting systems on the running rail and power supply rail (guide rail) of an LRT system, considering its reliable and safe operations in cold and snowy weather. We performed experiments at the LRT facilities in Uijeongbu, Korea, to analyze the time required to pre-heat the running rail and guide rail. In addition, we numerically analyzed the time by using modeling techniques with ANSYS, considering various weather conditions such as ambient temperature, wind speed, and humidity.
The numerical modeling results were verified by comparing them with experimental results. We analyzed the operating time for the snow melting system to minimize electric power consumption and maintain stable train operations.
Since the late 1980s a small number of research groups have been attracted with the idea of using induction heating technology for the processing of fibre reinforced polymer composites. Induction technology is suitable for the processing of thermoplastic and thermoset polymer materials but requires special susceptor additives (conductive materials) either in the form of structured fibres and fabric or particulate that can transform the electromagnetic energy into heat. This paper aims to summarize the principles of induction heating with respect to polymer composites processing taking a look first at material and equipment based process influences. State of the art applications and research activities are then reviewed, from thermoplastic composite welding, thermoset curing, selective material heating and fast mould heating technologies. Current simulation possibilities and available software tools have also been covered. Finally, some new ideas and possibilities for future developments in the field of polymer composites processing have been discussed.
This paper investigates the snow melting process on asphalt pavements as solar collector by experiments and numerical simulation. A numerical simulation method was used to predict the general design requirements for snow melting system of asphalt pavements, and a type of experimental asphalt snow melting system has been built using the design parameters obtained from the preceding simulation. Graphite powders were used to improve the thermal conductivity of asphalt concrete and thus resulting in an improved efficiency of asphalt collector. A laboratory snow melting test was performed after real snowstorm events. The effects of thermal conductive asphalt concrete (CAC) on snow melting performance and asphalt pavement temperature distribution were evaluated. The heat transfer in the asphalt slabs and the heat requirement for the snow melting were analyzed. The results that are obtained show that asphalt solar collector (ASC) provides us a better alternative method for snow melting. The higher fluid temperature is a positive way to improve the performance of snow melting system. However, it is unnecessary to keep a too high fluid temperature so as to reduce the waste of energy. The non-uniform temperatures in the asphalt slabs are noticeable. Furthermore, the heat-transmission and the snow melting performance can be enhanced using CAC.
Road ice and snow melting based on low temperature geothermal tail water is of significance to realize energy cascading utilization. A small scale ice and snow melting system is built in this work. Experiments of dynamic melting processes of crushed ice, solid ice, artificial snow and natural snow are conducted on concrete pavement. The results show that the melting process of ice and snow includes three phases: a starting period, a linear period and an accelerated period. The critical value of the snow free area ratio between the linear period and the accelerated period is about 0.6. The physical properties of ice and snow, linked with ambient conditions, have an obvious effect on the melting process. The difference of melting velocity and melting time between ice and snow is compared. To reduce energy consumption, the formation of ice on roads should be avoided if possible. The idling process is an effective pathway to improve the performance of melting systems. It is feasible to utilize geothermal tail water of about 40°C for melting ice and snow on winter roads, and it is unnecessary to keep too high fluid temperatures during the practical design and applications. Besides, with the exception of solid ice, the density and porosity of snow and ice tend to be decreasing and increasing, respectively, as the ambient temperature decreases.
The objective of this research is to examine the conductivity of asphalt mortar through the addition of electrically conductive fillers and fibers: graphite and steel wool, and prove that this material can be heated with induction energy. The effect of fibers content, sand–bitumen ratio and the combination of fillers and fibers on the resistivity of asphalt mortar was investigated. It was found that the percolation threshold happened sooner by adding electrically conductive fibers than by adding fillers. Percolation threshold was also found to be function of the sand–bitumen ratio and of the volume of fibers content. There is an optimum content of fibers for each sand–bitumen ratio, above which it is difficult to make the mixture and the electrical resistivity increases exponentially. Besides, in case of adding conductive fillers or a mixture of conductive fibers and fillers to the mastic, once the maximum conductivity is reached, it remains constant, independently of the volume of conductive filler added. Nano CT-scan (computed axial tomography) reconstructions were also used to visualize the fibers connected inside the mixture. Finally, to validate the research, three different samples were induction heated and their temperature variation was measured.
This paper aims to propose a hybrid system for snow storage/melting and air conditioning by using renewable energy-resources, and clarify the effects of an actual realized application. First, the outline of the system installed at an office building, which was completed in Sapporo, Japan in 2001, is shown. The hybrid system is composed of an underground thermal utility for snow melting by using vertical earth heat-exchangers and space cooling through seasonal cold storage of snow-and-ice cryogenic energy. Second, at the comparatively severe climatic conditions (the lowest outside air-temperature -9.2 °C and the amount of daily snowfall 8.1 cm), it was found that the underground thermal utilization system contributes to preventing freezing of a road surface, and that the road-surface exposure rate was approximately 90%. The effectiveness of this system on energy conservation, environmental protection and cost was verified through numerical analyses. Also, as a result of measuring snow-storage characteristics and space-cooling performance, the effective amount of snow stored on the first day of the space-cooling period was approximately 74%, which gave comparatively good agreement with the predicted value.
Increased application of chemical deicers for winter maintenance has resulted in increased concentrations of deicer constituents in the environment. The runoffs from the deicing operation have a deteriorating effect on soil and water quality. But the degree of impact is localized and it depends on various climatic factors and can also be attributed to the type of salts used and their storage conditions. This paper presents a review of the environmental impact of deicing chemicals.
In this research, an electrically conductive porous asphalt concrete, used for induction heating, was prepared by adding electrically conductive filler (steel fibers and steel wool) to the mixture. The main purpose of this paper is to examine the electrical conductivity and the indirect tensile strength of this conductive porous asphalt concrete and prove that it can be heated via induction heating. It was found that, to make porous asphalt concrete electrically conductive, long steel wool with small diameter is better than short steel fibers with bigger diameter. However, steel fibers with short length and big diameter have better strength reinforcement capability than steel wool with long length and small diameter. It was also proved that conductive porous asphalt concrete containing steel wool can be easily heated via induction heating. Finally, 10% (by volume of bitumen) of steel wool type 000 was proposed as an optimal content in porous asphalt concrete to obtain an optimal conductivity, a good induction heating rate and an acceptable indirect tensile strength. It is expected that the autogenous healing capacity of asphalt concrete will be enhanced with the increase of temperature during induction heating.
Hydronic or electric heating of pavement surfaces has been used in the prevention of ice formation and snow deposition with the aim of improving transportation safety. This paper describes a numerical model of a heated pavement and the snow melting processes occurring on its surface. A set of boundary conditions have been defined, and models of heat and mass transfer developed, that allow treatment of various surface and weather conditions associated with storm events. Given heat fluxes and weather data, this model can predict the transient surface conditions and temperatures including the extent of snow cover. Model development is described in this paper and its application to a representative snow melting system illustrated. A companion paper presents a validation exercise using data collected from a full-scale bridge snow melting system during a real storm event.
Water is one of the most studied compounds in existence: this site, by Martin Chaplin, South Bank University, London, draws together a selection of recently-published information about water. Key topics include: thirty-three anomalies of water and their explanations, and icosahedral water clusters. General information about water is also presented, including: the water molecule (spectra, orbitals); hydrogen bonding (dimer, pentamer orbitals); water ionisation (ion orbitals); polysaccharide hydration; protein hydration; nucleic acid hydration; data concerning water; the phase diagram of water, (hexagonal ice, cubic ice, ice-two). Some of the interactive pages require HyperChem Web Viewer or the Chime plug-in.
Vast networks of roads cover the earth and have numerous environmental effects including pollution. A major component of road runoff in northern countries is salt (mostly NaCl) used as a winter de-icing agent, but few studies of effects of road salts on aquatic organisms exist. Amphibians require aquatic habitats and chemical pollution is implicated as a major factor in global population declines. We exposed wood frog tadpoles to NaCl. Tests revealed 96-h LC50 values of 2,636 and 5,109 mg/l and tadpoles experienced reduced activity, weight, and displayed physical abnormalities. A 90 d chronic experiment revealed significantly lower survivorship, decreased time to metamorphosis, reduced weight and activity, and increased physical abnormalities with increasing salt concentration (0.00, 0.39, 77.50, 1,030.00 mg/l). Road salts had toxic effects on larvae at environmentally realistic concentrations with potentially far-ranging ecological impacts. More studies on the effects of road salts are warranted.
In order to study the heating process of water by the microwaves of 2.5-20 GHz frequencies, the authors have performed molecular dynamics simulations by adopting a nonpolarizable water model that has fixed point charges on a rigid-body geometry. All runs are started from the equilibrated states derived from the I(c) ice with given density and temperature. In the presence of microwaves, the molecules of liquid water exhibit rotational motion whose average phase is delayed from the microwave electric field. Microwave energy is transferred to the kinetic and intermolecular energies of water, where one-third of the absorbed microwave energy is stored as the latter energy. The water in ice phase is scarcely heated by microwaves because of the tight hydrogen-bonded network of water molecules. Dilute salt water is significantly more heated than pure water because of the field-induced motion of salt ions, especially that of large-size ions, by the microwave electric field and energy transfer to water molecules by collisions.
- R R Blackburn
- K M Bauer
- Amsler Sr
Blackburn R R, Bauer K M, Amsler Sr D E, et al. SNOW AND ICE CONTROL: GUIDELINES FOR
MATERIALS AND METHODS[R]. 2004.
Snow and ice control: guidelines for materials and methods
- R R Blackburn
- K M Bauer
- D E Sr