Simulation of Snow and Ice Melting on Energy-Efficient and Environmentally Friendly Thermally Conductive Asphalt Pavement

Abstract

Conventional asphalt pavement snow and ice removal methods suffer from issues such as time-consuming operations, high costs, and pollution from chemical de-icing agents. Commonly used thermally conductive asphalt concrete (TCAC) faces problems including limited filler diversity, high filler content, and elevated costs. To address these challenges, this study developed a thermally conductive asphalt concrete incorporating carbon fiber–silicon carbide composite fillers to provide a low-cost, energy-saving winter pavement snow melting solution and enhance eco-friendly de-icing performance. Finite element simulation software was employed to model its snow and ice melting performance, investigating the factors influencing this capability. Thermal conductivity was measured using the transient plane source (TPS) technique. The results show that with 0.3% carbon fiber, thermal conductivity reaches 1.43 W/(m·°C), 72.3% higher than ordinary asphalt concrete. Finite element simulations in finite element simulation software were used to model snow and ice melting, and strong agreement with field test data (correlation coefficients > 0.9) confirmed model reliability. Then, the finite element simulation software was used to study the effects of wind speed, temperature, laying power, and spacing on the snow and ice melting of TCAC. The simulation results show that the heating rate increases with TCAC thermal conductivity. Raising the power of the embedded carbon fiber heating cord reduces de-icing time but shows a threshold effect. In this study, asphalt pavement with high thermal conductivity was prepared using a low content of thermal conductive filler, providing a theoretical basis for sustainable pavement design, reducing energy use and environmental damage. TCAC technology promotes greener winter road maintenance, offering a low-impact alternative to chemical de-icing, and supports long-term infrastructure sustainability.

1. Introduction

Manual clearing, mechanical clearing, and spreading de-icing agents are the three main methods for removing snow and ice from road surfaces in winter. Manual and mechanical cleaning are time-consuming, costly, and easily cause damage to asphalt concrete pavements [1,2]. Although spreading snow melting agents is highly efficient, they fail to melt snow when the ambient temperature is below −3.91 °C [3,4]. Moreover, long-term use of snow melting agents is prone to cause concrete corrosion and environmental pollution [5,6,7], which has attracted great attention from the World Health Organization (WHO) and the International Energy Agency (IEA). To avoid this problem, using heating systems has become a research hotspot in pavement snow and ice melting. This solution involves laying heating wires or hot water pipes at the bottom of asphalt concrete pavements, and melting the snow on the pavement through heat transfer [8,9,10]. However, during the operation of the heating system, a large amount of heat is transferred to the subgrade or air, resulting in significant heat loss, and much more heat is required to melt the ice and snow on the pavement than expected. Chen [11] found that adding graphite to asphalt concrete can accelerate heat transfer in asphalt concrete and reduce energy loss. Hai Viet Vo and colleagues [12] delved into how different mixing approaches and graphite proportions impact the thermal conductivity of asphalt pavements. Moreover, they employed scanning electron microscopy (SEM) to observe the microstructure of asphalt concrete, aiming to gain a deeper insight into the mechanism behind the enhancement of thermal performance within the heat transfer structure system. Liu [13] added 25% iron oxide as an additive into silicon carbide powder to prepare asphalt concrete. It was discovered that the microwave heating rate of the asphalt concrete increased by 83%. Chamorro [14] explored the influence brought by incorporating carbon fiber into asphalt concrete on its road performance. They discovered that carbon fiber is capable of remarkably boosting the road performance of asphalt concrete and elevating the tensile stiffness. Wen [15] used graphite as an additive to improve the high temperature resistance, thermal conductivity, and aging resistance of asphalt concrete. Liu [16] found that graphite can cause the degradation of the mechanical properties of asphalt concrete, and, according to the results of the study, the mechanical properties of activated carbon modified by asphalt have improved in terms of aging resistance [17], carrying corrosion performance [18], and fatigue resistance [19]. Abubakar [20] and Wang [21] wove carbon fibers into different forms, then laid them inside concrete, and studied the effect of thermal power density on temperature through heating tests.

In recent years, with the gradual rise of finite element numerical simulation technology, more and more studies have combined tests with finite element numerical simulation and used finite element simulation software to predict test results. This has greatly reduced research work and provided support for the application of finite element simulation software in road snow and ice melting design. Han [22] used modeling and laboratory testing to investigate how environmental conditions exerted an impact on the heating performance of conductive rubber composites. Yi [23] layered the asphalt pavement structure and simulated the heat transfer process of a pavement system using the finite element method. Guo [24] employed finite element simulation to examine how the burial depth of carbon fiber heating cord impacts temperature transfer, suggesting that the optimal heating performance is achieved when the carbon fiber heating cord is positioned between the upper and lower layers. Zhang [25] integrated mechanical snow removal into the heating system and explored the snow removal efficiency of the combined method of electric heating snow melting and mechanical snow removal through finite element simulation.

Karimi [26] found through research that, while the use of steel fibers as thermal conductive additives increased the heating rate of asphalt concrete, it also resulted in drawbacks such as uneven temperature distribution and reduced overall integrity. Liu [27] conducted experiments using steel slag to replace 30% of the coarse aggregate in the preparation of thermally conductive asphalt concrete. It should be noted that, although research on asphalt concrete with thermal conductive materials and finite element simulation is extensive, it is evident that incorporating a single type of thermal conductivity additive into asphalt concrete remains flawed, while partially replacing aggregates with thermal fillers incurs significant costs. There is a noticeable scarcity of studies focusing on the snow and ice melting performance of asphalt concrete pavements produced with two-phase composite thermal conductive fillers, which limits the development of thermal conductive asphalt pavement. Therefore, research on the snow and ice melting performance of asphalt concrete pavements prepared with two-phase composite thermal conductive fillers has great importance.

In this study, this paper researches two-phase composite thermal conductive asphalt concrete incorporating carbon fiber and silicon carbide. By leveraging finite element simulation software, a calculation model for the snow and ice melting of thermal conductive asphalt concrete pavement containing carbon fiber and silicon carbide is established. The credibility of this model is verified via laboratory tests that duplicate the model parameters and working conditions utilized in the simulation. Furthermore, the effects of the asphalt pavement’s thermal conductivity, the power and spacing of the heating cord, wind speed, and ambient temperature on the snow and ice melting of the thermal conductive asphalt pavement are investigated. This research reduces the dependence on chemical snow melting agents and improves the energy efficiency of heat conduction, providing a valuable reference for environmentally friendly engineering practices related to asphalt pavement snow and ice melting.

2. Materials and Methods

2.1. Raw Materials

TCAC specimens were prepared using Grade A 70 paving asphalt, limestone mineral filler, basalt aggregates, chopped carbon fibers, and silicon carbide micropowder. Grade A70 paving asphalt was produced by China Petroleum & Chemical Corporation as the research subject, in compliance with JTG E20-2011 (Standard test methods of bitumen and bituminous mixtures for highway engineering) [28]. Both the basalt aggregate and mineral powder are sourced from a gravel pit located in Wuhan, Hubei Province, China, all meet JTG 3432-2024 (Test Methods of Aggregate for Highway Engineering) [29]. The chopped carbon fiber and silicon carbide micropowder come from a company in Wuhan, Hubei Province. And their physical properties are shown in

Table 1. Basic parameters of 70# matrix asphalt.

Penetration	Softening Point	Ductility	Open Flash Point	Residual Penetration Ratio	Residual Ductility
7.3 mm	47 °C	58 cm	>300 °C	67.5%	8 cm

,

Table 2. Basic parameters of basalt aggregate.

Crushing Value	Los Angeles Abrasion Loss	Water Absorption	Crushing Strength	Slender Flat Particle Content
9.5 MPa	3.7%	0.9%	160 MPa	4%

,

Table 3. Basic parameters of chopped carbon fiber.

Tensile Strength	Tensile Modulus	Density	Resistivity	Monofilament Diameter
4825 MPa	230 GPa	1.82 g/cm3	1.75 × 10−3 W	7.3 mm

and

Table 4. Basic parameters of silicon carbide micropowder.

Carbon Content	Bulk Density	Diameter	Thermal Conductivity	Appearance
98.5%	3.18 g/cm3	0.073 mm	270 W/(m·K)	Green powder

. The basalt aggregates gradation used in the test is shown in

Table 5. Design gradation sieve passage rate.

Sieve Size/mm	16	13.2	9.5	4.75	2.36	1.18	0.6	0.3	0.15	0.075
Total passing/%	100	95	77	53	37	27	19	14	9	5

.

2.2. Specimen Preparation

To determine the parameters of TCAC, this paper refers to the method of “Test Procedure for Asphalt and Asphalt Mixture in Highway Engineering” (JTGE 20-2011) in China to prepare rutted slab specimens of this material, an asphalt concrete specimen with particle size gradation of AC-13 and an oil/rock ratio of 4.7%. A mineral powder constituting 5% of the total asphalt concrete volume, and a silicon carbide powder equal volume replacement of all mineral powders, were added to account for the mass of asphalt concrete for 0.1%, 0.3%, and 0.5% of the short-cut carbon fibers, respectively; before mixing, the aggregates were placed in 105 °C, heated for 6 h, and the asphalt was placed in 150 °C and heated for 3 h. During the heating process, the aggregate temperature is tested to meet the temperature requirements before mixing. When mixing asphalt concrete, first the conventional aggregate and short-cut fiber are mixed, then asphalt is added and mixed; finally, silicon carbide micropowder is added and mixed. Ordinary asphalt concrete maintains the same base composition as TCAC, differing only in the absence of carbon fiber and silicon carbide thermal conductive fillers. The Marshall residual stability of thermal conductive asphalt concrete is 96%, the freeze–thaw splitting tensile strength ratio is 94%, and the dynamic stability is 3672 times/mm, all of which are in line with the road performance.

2.3. Thermal Property Testing

Thermal conductivity and specific heat capacity are critical parameters employed to evaluate the thermal properties inherent in asphalt concrete. Gustafsson [30] has put forward a transient planar source method (TPS), which is specifically designed for conducting measurements of thermal conductivity and thermal diffusivity on solid materials. This measurement method has been widely used in the academic community and is described in detail in ISO22007-2 [31]. ADL-ZARRABI [32] investigated the applicability of TPS in asphalt using sensors of different sizes. Pan [33] investigated how the amount of graphite in asphalt influenced its thermal conductivity and thermal diffusivity using TPS. The applicability of transient planar source approach in asphalt concrete has been confirmed through extensive research by many scholars [34,35,36].

Each experiment in this paper employed three parallel replicates. The permissible error for parallel testing of specimens is 10%. Values exceeding this range should be discarded and retested. According to the test results shown in

Table 6. Material parameters.

Material	Density (kg/m3)	Thermal Conductivity (W/m·°C)	Specific Heat Capacity (J/kg·°C)
48 k carbon fiber	2000	60.3	712
Ordinary asphalt concrete	2250	0.83	1100
TCAC	2400	1.23/1.43/1.03	1300

, the thermal conductivity can be significantly increased by including silicon carbide and carbon fibers into asphalt mixtures. The thermal conductivity first increased and subsequently decreased as the dosage of carbon fiber increased. Specifically, the thermal conductivity was 1.23 W/(m·°C) with a dose of 0.1% carbon fiber. When the carbon fiber content reached 0.3%, it peaked at 1.43 W/(m·°C), a 72.3% increase over regular asphalt concrete. However, the thermal conductivity dropped to 1.03 W/(m·°C) when the carbon fiber concentration was increased to 0.5%.

This demonstrates that an appropriate amount of carbon fiber markedly enhances the thermal conductivity of asphalt specimens. Conversely, excessive carbon fiber addition impedes heat transfer. There are two reasons that contribute to this phenomenon. Firstly, during mixing, carbon fibers adsorb a portion of the free asphalt. This promotes densification during the curing process and facilitates fiber overlap, thereby forming continuous pathways for heat conduction and improving thermal conductivity. Secondly, the continued addition of carbon fibers beyond the optimum level adsorbs excessive free asphalt. This results in increased void content within the asphalt concrete. As voids hinder the efficient propagation of heat through the material, this ultimately causes the thermal conductivity to decrease.

2.4. Simulation Model Creation

Finite element analysis is a highly versatile and practical numerical analysis method. It solves complex problems by replacing them with simpler ones, dividing the domain into numerous small finite element subdomains. An approximate solution is assumed for each element, and the overall solution is derived by satisfying the conditions across the entire domain. As the earliest finite element software to enter the domestic market and currently the most widely recognized in China, the ANSYS transient thermal module excels at calculating internal temperature distributions within models using thermal physics parameters. For the temperature field simulation analysis of asphalt pavement required in this study, the transient thermal module within the 2024 version of ANSYS software was selected as the tool for analyzing the pavement snow melting and de-icing model.

The carbon fiber–silicon carbide-enhanced TCAC specimen consists of two layers with overall dimensions of 300 mm (length) × 300 mm (width) × 100 mm (height). The upper 50 mm layer is the TCAC, while the lower 50 mm layer is ordinary asphalt concrete. Carbon fiber heating cord is embedded along the bottom surface of the TCAC layer, positioned 46 mm below its top surface. The cord is arranged in parallel in a U-shaped pattern with a spacing of 60 mm between adjacent parallel runs. A 5 mm thick layer of ice is paved on top of the asphalt concrete.

For the finite element analysis, the entire model is discretized using tetrahedral elements. To ensure interfacial temperature continuity between the heating cord and the TCAC, the mesh around the heating cord is refined. Temperature measurement points were set up on the surface of TCAC at 60 mm intervals along the horizontal direction and at 10 mm intervals along the depth direction at the centerline position. The specific results of the model are shown in Figure 1.

In the simulation, the electrical power of the carbon fiber heating cord is achieved by applying a temperature load across its surface. Given that the length of the carbon fiber heating cord is considerably greater than its cross-sectional dimensions, temperature variations along the axial direction are negligible. The 48 K carbon fiber heating cord employed in this study determines an input power of 10 W/m to 50 W/m, with the heat flux density range set between 1800 W/m² and 2900 W/m². At wind speeds of 2 m/s and 5 m/s, the convective heat transfer coefficients are 6 and 8 (W/(m²·°C)). A 0.1 m grid size was employed, with the entire model meshed using tetrahedral elements. The asphalt concrete and carbon fiber heating cord were subject to refined meshing to ensure more accurate temperature transfer.

2.5. Simulation Model Validation

To validate the accuracy of the finite element model, the material parameters of asphalt concrete with a carbon fiber content of 0.1% were applied. An ice layer was placed on the model surface under ambient conditions of −5 °C and a wind speed of 3 m/s. The embedded carbon fiber heating cord within the TCAC layer was powered continuously to simulate de-icing performance on pre-snowed pavements.

For comparative validation, a physical specimen corresponding to the finite element model was prepared. An ice layer of identical thickness was applied to its surface. This physical specimen was then placed in the same environmental conditions as the simulation (−5 °C and 3 m/s wind speed). The carbon fiber heating cord in the physical specimen was energized for the same duration as specified in the simulation to ensure data comparability. Illustrations of the physical specimen and the simulation model are provided in Figure 2.

In the test, a layer of snow was placed on the model’s surface simultaneously with the activation of the carbon fiber heating cord. For another group, an equal thickness of snow was laid on the model’s surface after the carbon fiber heating cord had been heated for 1 h, which constituted the preheating procedure. The results of the simulation and the field test concerning snow and ice melting are shown in Figure 3.

As can be observed from Figure 3, the variation trends and results of the numerical simulation outcomes and the measured values from the field snow and ice melting tests are essentially in agreement. Before the temperature reaches 2 °C, whether or not the asphalt concrete is preheated, the pavement temperature undergoes a rapid increase. When the temperature reaches to 2 °C, the pavement temperature enters a stable phase. At this point, heat exchange begins between the pavement surface and the ice layer. Subsequently, the ice melts into liquid water, which then seeps downward, leading to a reduction in the pavement temperature. However, this complex phase change and seepage mechanism was not simulated in the finite element model. Consequently, significant deviations arose between the measured and simulated temperature values for specimens without a preheating process. When the ice layer has mostly melted, the pavement temperature begins to rise slowly.

Through the Pearson correlation analysis of the finite element simulation test data and the field snow and ice melting test data, it can be seen that the correlation coefficient R between numerical simulations and field measurements reaches 0.98 in the preheated test. For the non-preheated test, this coefficient measures 0.93. Both values exceed 0.9, demonstrating significant correlation (p < 0.01) between simulation and experimental outcomes; finite element numerical simulation can accurately simulate the temperature change law of TCAC pavement in different situations.

3. Results and Discussion

The pavement snow melting and ice melting process comprises two distinct phases: the pre-melting phase and the melting phase. The pre-melting phase, a key period for evaluating pavement thermal conductivity, occurs when the pavement temperature increases from its initial state to the critical snow melting threshold temperature under continuous heating from the embedded carbon fiber heating cord within the conductive asphalt concrete layer. Once this critical temperature is reached, the melting phase commences, involving heat exchange between the pavement surface and the ice layer. During this phase, the pavement temperature typically stabilizes initially and then rises slowly as the ice layer undergoes phase change and melts, culminating in its complete liquefaction. Since pavement temperature serves as an indicator of ice melting progress, investigating the influence of altering specific pavement parameters during each phase on temperature profiles reveals the impact of various factors on the thermal performance and effectiveness of conductive asphalt pavement systems designed for snow and ice melting.

The thermal conductivity of concrete is mainly controlled by changing the content of thermal conductive filler; too large a content will increase the cost of thermal conductive asphalt pavement, and too small will lead to a poor snow melting effect on the pavement. The spacing of the heating cords will not only affect the distribution of the internal temperature of the concrete but also indirectly affect the cost, and smaller spacing means that more heating cords are needed. Wind speed and ambient temperature will affect the heat exchange and heat transfer of the asphalt pavement. It is necessary to analyze the internal temperature distribution to reduce heat loss to the base layer to meet the actual engineering and research needs. Therefore, this study studies the thermal conductivity, spacing of heating cords, wind speed, ambient temperature, and internal temperature distribution of thermally conductive asphalt concrete.

3.1. Influence of Thermal Conductivity on Heating Rate

The thermal conductivity of asphalt concrete was determined to be 0.83, 1.03, 1.23, and 1.43 W/(m·K), based on the specimens made for this study and the finite element model that was created. The temperature at which the specimens were placed was −5 °C. The results of measuring the heating rates of asphalt concrete under various thermal conductivity coefficients while the carbon fiber heating cord was left to continue heating for three hours are shown in

Table 7. Surface temperature and warming rate of TCAC with different thermal conductivity.

Thermal Conductivity W/(m·K)	Surface Temperature °C	Rising Temperature Rate °C/min
0.83	6.378	0.0632
1.03	8.374	0.0743
1.23	10.841	0.0880
1.43	13.616	0.1034

. The whole temperature progression graphs throughout the heating time are shown in Figure 4.

As illustrated in Figure 5, under identical environmental conditions, the temperature rise rate of the specimens exhibits a positive correlation with thermal conductivity. Specifically, asphalt concrete specimens with thermal conductivities of 1.03, 1.23 W/(m·K), and 1.43 W/(m·K) demonstrated temperature rise rates equivalent to 117.6%, 139.2%, and 163.1% of the specimen with a reference thermal conductivity of 0.83 W/(m·K). These results clearly demonstrate the enhancement in thermal diffusion rate resulting from improved thermal conductivity.

Based on the principles outlined above, engineering practice can incorporate thermally conductive fillers such as graphene, carbon fibers, or metal oxides to modify asphalt concrete. This approach facilitates the formation of a three-dimensional continuous heat-conduction network within the material, thereby significantly enhancing its bulk thermal conductivity. However, it must be emphasized that, while improving the thermal conductivity of asphalt concrete pavements, the selection and design of conductive fillers—including their type, particle size distribution, and dosage—must be optimized according to site-specific environmental requirements. This optimization is essential to ensure compliance with essential pavement performance requirements.

3.2. Influence of Heating Cord Power on De-Icing Time

To address the practical engineering requirements of minimizing ice and snow melting duration while ensuring commuting efficiency and driving safety, this study investigates optimal power levels for embedded carbon fiber heating cord. Using the finite element model established in this paper, simulations were conducted under two ambient temperatures (−5 °C and −10° C) with constant 2 m/s wind speed. Four powers of the carbon fiber heating cord, set to 900, 1200, 1500 W/m², and 1800 W/m², were applied to the heating cord. The time for the asphalt concrete surface to reach the critical ice melting temperature was recorded. The test results are shown in

Table 8. Time of reaching melting point at different power levels.

Power(W/m2)	Time (min)
	−5 °C	−10 °C
900	78	132
1200	51	87
1500	38	67.5
1800	23	54

.

As shown in Table 8, with the ambient temperature maintained at −5 °C, the power output of the carbon fiber heating cord rises from 900 W/m² to 1800 W/m². The average surface temperature of the concrete pavement goes up to the temperature needed for ice melting, shortening the time from 78 min to 23 min. When the ambient temperature is −10 °C, the power output of the cord increases from 900 W/m² to 1800 W/m². The average surface temperature of the concrete reaches the temperature needed for ice melting, cutting the required time from 132 min to 54 min. This suggests that, under fixed environmental temperature and wind speed conditions, enhancing the power of the carbon fiber heating cord lowers the concrete surface temperature necessary for water to melt. Therefore, as the power of the cable increases, the time needed for the concrete surface temperature to reach the melting point also decreases.

Notably, raising the carbon fiber heating cord’s output from 900 W/m² to 1200 W/m² lowers the average time needed for the asphalt concrete surface temperature to reach the snow melting temperature by 27 min at an ambient temperature of −5 °C. However, further increases to 1500 W/m² and 1800 W/m² shorten the time by only 13 min and 15 min, respectively, relative to the preceding power level. These observations reveal a pronounced threshold effect: beyond approximately 1200 W/m², additional power yields diminishing reductions in melting time. Consequently, to enhance snow melting efficiency, the layout and operating parameters of the carbon fiber heating cord should be optimized rather than simply increasing power density.

3.3. Influence of Heating Cord Spacing on Thermal Performance

The spacing of the carbon fiber heating cord exerts a decisive influence on the temperature field within asphalt concrete. Excessively small spacing tends to generate localized overheating, accelerating asphalt aging during snow melting operations, whereas overly large spacing produces pronounced thermal non-uniformity, leaving snow or ice in regions remote from the cord un-melted. In the foregoing investigation, an areal power density of 1200 W/m² was identified as the threshold at which energy efficiency is maximized. Leveraging the validated finite element model developed herein, a parametric study was therefore conducted under the following boundary conditions: ambient temperature −5 °C and cable output 1200 W/m². Cord spacings of 40, 50, 60, 70, and 80 mm were examined in conjunction with asphalt thermal conductivities of 0.83, 1.03, 1.23, and 1.43 W/(m·K). The time required for the mean pavement temperature to reach snow melting was recorded for each configuration; the results are shown in Figure 5.

The time needed for the pavement temperature to achieve the ice and snow melting temperature decreases as thermal conductivity increases, as shown in Figure 5, under the same spacing circumstances. It takes 163 min for the asphalt concrete surface temperature to reach the snow melting temperature in asphalt concrete with a thermal conductivity of 0.83 W/(m·°C) at an 80 mm spacing, but it only takes 76 min for the thermal conductivity of 1.43 W/(m·°C). This phenomenon shows that high thermal conductivity materials facilitate effective heat transmission. Furthermore, for a specific thermal conductivity, a larger laying spacing is associated with a longer required time. When the thermal conductivities are 0.83 W/(m·°C) and 1.03 W/(m·°C), the time required for the average pavement temperature to reach the ice melting temperature increases significantly when the laying spacing exceeds 60 mm. On the contrary, the time required for asphalt concrete with thermal conductivities of 1.23 W/(m·°C) and 1.43 W/(m·°C) has a linear relationship with the laying spacing. That is, thermal conductivity has a threshold effect on the increase of asphalt concrete surface temperature heating rate. In summary, to improve snow melting efficiency, it is advisable to select materials with high thermal conductivity and reduce the laying spacing. This can shorten the heating time and ensure that the pavement temperature meets the snow melting requirements in a timely manner. But too small spacing will lead to temperature overflow, resulting in a waste of resources. Moreover, the smaller the spacing, the more complicated and difficult the construction will be, and the higher the required labor and material costs will be. Therefore, in the subsequent research, asphalt concrete with a thermal conductivity of 1.23 W/(m·°C) will be used, and the carbon fiber heating cord will be laid at a power density of 1200 W/m² and a spacing of 60 mm.

3.4. Influence of Wind Speed and Ambient Temperature on Asphalt Concrete

Wind speed and ambient temperature are important factors affecting driving safety in winter. Based on the finite element model in the research, the carbon fiber heating cord inside the asphalt concrete was continuously powered and heated for 6 h, and the environmental conditions were designed as shown in

Table 9. Design for the effects of different temperatures and wind speeds on TCAC.

Case	Ambient Temperature (°C)	Wind Speed (m/s)
1	−5	2
2	−5	5
3	−5	8
4	−10	2
5	−10	5
6	−10	8

.

As shown in

Table 10. Stable temperature and heating rate of TCAC under different conditions.

Case	Stable Temperature (°C)	Heating Rate (°C/min)
1	10.083	0.041
2	7.022	0.033
3	4.392	0.026
4	4.796	0.041
5	2.772	0.035
6	1.088	0.030

, under a constant ambient temperature, both the final stable temperature and heating rate of asphalt concrete decrease gradually with increasing wind speed. When wind speed is held constant, the final stable temperature of asphalt concrete increases gradually as ambient temperature rises, while the heating rate decreases progressively. Specifically, for asphalt concrete subjected to the same heating duration, the final stable temperature exhibits a positive correlation with ambient temperature and a negative correlation with wind speed, whereas the heating rate is negatively correlated with both ambient temperature and wind speed. A comprehensive analysis of these two factors reveals that wind speed exerts a greater influence on the final stable temperature of asphalt concrete than ambient temperature.

As shown in Figure 6, under constant wind speed at 2 m/s, the asphalt concrete surface takes 16, 60 min, and 170 min to reach the ice melting temperature at ambient temperatures of 0, −5 °C, and −10 °C, with corresponding average surface temperatures of 1.768, 1.934 °C, and 1.641 °C. At 5 m/s, the time increases to 24, 80 min, and 230 min under the same ambient temperatures, with average surface temperatures of 2.117, 1.952 °C, and 1.748 °C. At 8 m/s, the time required is 32 min and 120 min at 0 °C and −5 °C, with average temperatures of 2.22 °C and 1.773 °C. However, at −10 °C under this wind speed, the asphalt concrete stabilizes at 1 °C, failing to reach the ice melting temperature.

When the wind speed remains constant, higher ambient temperatures will lead to an increase in the effective temperature difference (ΔT) between the specimen and the surrounding environment, which in turn speeds up the heating rate. Therefore, under the condition of constant wind speed, there is a positive correlation between the heating rate of asphalt concrete and the ambient temperature.

As shown in Figure 7, under the condition of a constant ambient temperature, when the temperature is maintained at 0 °C, it takes 16, 24, and 32 min, respectively, for the asphalt concrete’s surface temperature to reach the ice melting point at wind speeds of 2, 5, and 8 m/s. At wind speeds of 2, 5, and 8 m/s, the asphalt concrete’s surface temperature takes 60, 80, and 120 min, respectively, to reach the ice melting temperature while the temperature is kept at −5 °C. At 2 m/s and 5 m/s wind speeds, the asphalt concrete’s surface temperature takes 170 and 230 min, respectively, to reach the ice melting temperature while the temperature is maintained at −10 °C. However, at a wind speed of 8 m/s, the surface temperature of asphalt concrete cannot reach the ice melting temperature. Under the condition of a constant ambient temperature, the heating rate of asphalt concrete is inversely correlated with wind speed.

3.5. Internal Temperature Distribution of Asphalt Concrete

For snow and ice pavements to be used practically in engineering, the horizontal temperature distribution is essential. Accordingly, it is crucial to ensure the uniformity of the temperature distribution of the pavement surface layer in addition to transferring the heat generated by the carbon fiber heating cord to it in the shortest amount of time in order to successfully remove ice and snow from the driving zone.

As shown in Figure 8 and Figure 9, following stabilization, the specimen surface temperature is proportional to the surrounding air temperature. The H3 location, which is situated in the middle of the specimen, has the highest temperature, while the H2, H3, and H4 temperature measurement sites have comparable temperatures. In comparison to the center, the temperatures at the H1 and H5 locations near the periphery are comparable and marginally lower. This is because the temperature superposition effect causes the surface temperature at the H3 point to be the highest of all surface temperatures, somewhat higher than the surrounding temperatures. Additionally, it is verified that carbon fibers and silicon carbide micropowder are evenly dispersed throughout the asphalt mixture based on the configuration of the temperature monitoring lines and the data collected. The lowest temperature at the TCAC surface layer edge, where heat from the heating cable is delivered, is 3.59 °C once the temperature has stabilized. This temperature can satisfy the ice melting requirement, suggesting that the temperature distribution on the mixture surface is improved by using silicon carbide micropowder and carbon fibers as thermally conductive aggregates, and the temperature of the asphalt concrete surface can achieve the purpose of snow melting.

As evidenced by the specimen internal temperature distribution, the internal temperature of the TCAC is significantly greater than that of regular asphalt concrete. Additionally, the TCAC’s temperature increase rate is higher. The temperature of the specimen steadily rises in the TCAC as the depth of the temperature measuring point gradually increases. Compared to the L2 temperature measurement point in the TCAC at the same location, the temperature at the L4 temperature measurement point, which is situated in the center of the regular asphalt concrete, is noticeably lower. Furthermore, according to the temperature cloud map, after the specimen starts to be heated, the temperature mainly diffuses into the TCAC. This indicates that, by regulating the properties of asphalt concrete to form heat channels, the efficiency of snow and ice melting is effectively improved.

4. Conclusions

This study prepared low-cost, high-performance thermally conductive asphalt pavements by incorporating a small amount of a two-phase composite thermal conductive filler comprising silicon carbide and carbon fibers. At the same time, a finite element analysis software ANSYS was used to study the factors influencing the snow and ice melting ability of TCAC pavement. The conclusions are as follows:

(1)

The accuracy of the calculation model was validated through experiments using TCAC specimens with the same dimensions as those in the simulation tests under identical working conditions. The on-site snow and ice melting test on thermal conductive asphalt concrete pavement and the finite element numerical simulation tests showed good agreement in both experimental data results and variation trends; however, it is impossible to simulate the effect of ice melting into water on asphalt pavement temperature. Through the Pearson correlation analysis of the finite element simulation test data and the field snow and ice melting test data, it can be seen that the correlation coefficient R between numerical simulations and field measurements reaches 0.98 in the preheated test. For the non-preheated test, this coefficient measures 0.93. Both values exceed 0.9, demonstrating significant correlation (p < 0.01) between simulation and experimental outcomes.

(2)

The specimens’ rate of heating is positively connected with the thermal conductivity of the TCAC under identical external conditions. In comparison to the asphalt concrete specimen with a thermal conductivity of 0.83 W/(m·K), the heating rates of the specimens with thermal conductivities of 1.03, 1.23 W/(m·K), and 1.43 W/(m·K) are 117.6%, 139.2%, and 163.1%, respectively. This implies that, by properly adding thermal conductive fillers for modification, the overall thermal conductivity of asphalt concrete can be successfully increased, creating a three-dimensional continuous heat transport network inside the concrete.

(3)

Increasing carbon fiber heating cord power sharply shortens TCAC surface temperature rise time to the snow melting threshold; a rise from 900 to 1800 W/m² cuts it from 78 to 23 min. Cord laying spacing also affects TCAC with 0.83 and 1.03 W/(m·°C) thermal conductivity; time rises notably over 60 mm spacing. At 1.23 and 1.43 W/(m·°C), TCAC shows a linear spacing time relation, revealing a threshold effect.

(4)

Heated for the same duration, the TCAC’s ultimate stable temperature correlates negatively with wind speed and positively with ambient temperature. Both factors correlate negatively with the TCAC heating rate. The time for the ice melting to begin follows rules: a constant wind brings a longer time at lower temperatures (24 min at 0 °C and 230 min at −10 °C in 5 m/s, an 858% increase in time). A constant temperature means a longer time at higher winds (60 min at 2 m/s and 120 min at 8 m/s at −5 °C, doubling the time).

In this study, TCAC reduces environmental pollution caused by traditional snow melting agents by reducing reliance on chemical snow melting agents through efficient active snow melting. At the same time, compared with ordinary asphalt concrete, TCAC can shorten the time required for melting snow by 43% and reduce the energy consumption in the snow melting process when the power of the carbon fiber heating line is 1200 W/m² and the spacing is 60 mm. The heating power can be determined through ANSYS simulation to avoid energy waste caused by high-power heating and meet the needs of low-carbon energy saving. It offers a new option for the sustainability and environmental friendliness of asphalt pavement engineering. However, only short-term thermal performance and snow melting efficiency tests of TCAC (such as the indoor thermal conductivity test and short-term snow melting simulation and test) are carried out, and the attenuation law of TCAC thermal conductivity and the mechanical properties during long-term use are not involved, which cannot fully reflect its long-term engineering applicability. The simulated and tested environmental conditions are concentrated on a wind speed of 2 m/s to 8 m/s and a temperature of −10 °C to 0 °C, and the applicability of the model and conclusions in extreme environments needs to be further verified.