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Conductive asphalt concrete with high thermal conductivity has been proposed to improve the solar energy collection and snow melting efficiencies of asphalt solar collector (ASC). This paper aims to provide some insight into choosing the basic materials for preparation of conductive asphalt concrete, as well as determining the evolution of thermal...
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ABSTRACT
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Citations
... This raises concerns about its effectiveness on heterogeneous materials such as asphalt concrete [25]. Nevertheless, there are a limited number of studies in the literature in which the thermal properties of asphalt concrete have been measured using the TPS method [26,27]. However, the suitability of the method for asphalt concrete is not elaborated in these studies. ...
... For instance, Tang et al. [26] investigated the effect of the mixing mechanism on the thermal conductivity of asphalt solar collectors using the TPS method under the assumption that asphalt concrete is a continuous and isotropic material. In another study by Pan et al. [27], the TPS method was used to investigate how freeze-thaw cycles and aging affect the mechanical and thermal properties of asphalt concrete samples. ...
The structural performance of asphalt concrete is highly dependent on its thermal properties, especially in regions where daily or seasonal temperature variations are significant. In mechanistic design methods, thermal properties (specific heat, thermal conductivity, and coefficient of thermal expansion) are necessary to estimate the thermal behavior of asphalt concrete. However, the measurement of these properties is still a challenge, not only because of the heterogeneous structure of asphalt concrete but also because of the limitations imposed by the size of the test samples and the reliability of the measurement methods. In this study, a practical method, the Transient Plane Source (TPS), is proposed to measure the thermal conductivity of laboratory-produced asphalt concrete samples. To determine how thermal conductivity is affected by the maximum aggregate size, air voids, and aggregate source, a series of asphalt mixtures are compacted using the Superpave gyratory compactor to produce test samples. To determine the possible relationship between microstructural and thermal properties, which has not been investigated in previous studies, an image analysis is also performed to calculate the number of contact points and the total aggregate area in each sample. The statistical analyses show that all mixture properties, i.e., maximum aggregate size, air void content, and aggregate source, are significant, with the aggregate source having the greatest influence on the thermal conductivity of the samples. It is also shown that the TPS method is sensitive to the properties of the contact area, which significantly affects the reliability of the measurements.
... This raises concerns about its effectiveness on heterogeneous materials such as asphalt concrete [25]. Nevertheless, there are a limited number of studies in the literature in which the thermal properties of asphalt concrete have been measured using the TPS method [26,27]. However, the suitability of the method for asphalt concrete is not elaborated in these studies. ...
... For instance, Tang et al. [26] investigated the effect of the mixing mechanism on the thermal conductivity of asphalt solar collectors using the TPS method under the assumption that asphalt concrete is a continuous and isotropic material. In another study by Pan et al. [27], the TPS method was used to investigate how freeze-thaw cycles and aging affect the mechanical and thermal properties of asphalt concrete samples. ...
The structural performance of asphalt concrete is highly dependent on its thermal properties, especially in regions where daily or seasonal temperature variations are significant. In mechanistic design methods, thermal properties (specific heat, thermal conductivity, and coefficient of thermal expansion) are necessary to estimate the thermal behavior of asphalt concrete. However, the measurement of these properties is still a challenge, not only because of the heterogeneous structure of asphalt concrete but also because of the limitations imposed by the size of the test samples and the reliability of the measurement methods. In this study, a practical method, the Transient Plane Source (TPS), is proposed to measure the thermal conductivity of laboratory-produced asphalt concrete samples. To determine how thermal conductivity is affected by the maximum aggregate size, air voids, and aggregate source, a series of asphalt mixtures are compacted using the Superpave gyratory compactor to produce test samples. To determine the possible relationship between microstructural and thermal properties, which has not been investigated in previous studies, an image analysis is also performed to calculate the number of contact points and the total aggregate area in each sample. The statistical analyses show that all mixture properties, i.e., maximum aggregate size, air void content, and aggregate source, are significant, with the aggregate source having the greatest influence on the thermal conductivity of the samples. It is also shown that the TPS method is sensitive to the properties of the contact area, which significantly affects the reliability of the measurements.
... The results of the EUI calculation for scenario B are summarized in Table 3. The thermal conductivity (unit: W/m·K) of these roof coverings is 0.63 [54] for reflective coating and 1.594 for asphalt shingle [55]. The EUI value for Scenario B1 demonstrated the reflective capabilities of using a reflective coating, efficiently deflecting heat from sunlight. ...
The development of high-rise buildings worldwide has given rise to significant concerns regarding their excessive electricity consumption. Among the various categories of high-rise structures, hotels used for business and conferences stand out as particularly extravagant in their energy use. The consequence arising from excessive energy usage is an escalation in carbon emissions, which is a primary driver of global warming. Therefore, this study aims to investigate the energy use intensity (EUI) of a hotel building located in Jakarta, Indonesia. In order to improve energy performance, this study explored various options for renovating the building envelope, such as incorporating insulation and a roof covering, as well as implementing building-integrated photovoltaics (BIPV). The building envelope renovations demonstrated a notable reduction in energy use by 15.8–27.7% per year. BIPV, such as curtain walls and double-skin façades, generated an energy use reduction of 4.8–8.6% per year. Remarkably, by combining the two approaches (i.e., adding insulation and a roof covering in the building envelope and adopting BIPV as double-skin façades), the potential reduction in energy use reached up to 32.2% per year. The findings can assist decision-makers in developing building renovation strategies for high-rise buildings while considering energy conservation.
... As can be seen, the temperature loss rate is increased by increasing the WSS content in the mixtures so that the time required to reduce the temperature of the samples from 70°C to 50°C decreases by 15% and 31% when 3% and 6% of WSS are used, respectively. The reason is that the thermal conductivity of WSS is about 50 times greater than that of asphalt concrete (Pan et al. 2017;Alikhani and Latifi 2022). As a result, the thermal conductivity of asphalt concrete is increased by adding WSS. ...
Increasing the temperature affects the healing potential of asphalt mixtures significantly. However, it can lead to overheating in some parts of the specimens and cause damage. Thus, the healing temperature should be decreased in order to reduce the risk of overheating, which can affect the healing performance adversely. This research aims to investigate the probability of local overheating in asphalt mixtures during the induction heating of the mixtures containing different percentages of waste steel shavings (WSS). The healing procedure of the mixtures was simulated by placing the fractured hot-mix asphalt samples in a microwave so that the fractured surfaces are healed and stuck together. The healing resistance was evaluated by conducting the fracture test on the healed specimens and comparing the results to those of the intact specimens. The results showed that increasing the healing temperature to more than 70°C and the existence of WSS additives increase the probability of overheating in asphalt mixtures. The results indicated that the intermittent heating is effective to reduce the risk of overheating. As the healing procedure accelerates when the temperature increases to more than the softening point, it is recommended that, during intermittent heating, the samples should be cooled down to the temperature of the softening point during the rest period so that the temperature of the sample does not fall below the softening point of the bitumen during healing. By doing this, in addition to reducing the risk of overheating, the healing performance improves without increasing energy consumption.
... A Finite Element Method (FEM) simulation by Mavros [19] was in agreement with the above description. Furthermore, the road temperature remains almost the same, given that the asphalt conductivity, as well as its thermal capacity, is one order of magnitude higher than those of the tyre rubber, as reported by [32]. ...
... A Finite Element Method (FEM) simulation by Mavros [19] was in agreement with the above description. Furthermore, the road temperature remains almost the same, given that the asphalt conductivity, as well as its thermal capacity, is one order of magnitude higher than those of the tyre rubber, as reported by [32]. As soon as the surface area previously in contact with the ground loses such a contact, the temperature of the first layer rises again, returning in thermal equilibrium with the temperature of the rubber surface layer until ΔS, after a full tyre rotation, returns into contact with the ground. ...
Featured Application: Advanced thermo-mechanical tyre models, real time vehicle dynamic simulation , heat transfer calcualtion. Abstract: Tyres are one of the most important elements of a vehicle because they are the link to the road and have a huge impact on traffic-related pollution. Knowing their behaviour, thus being able to use them at their best and reducing their wear rate, is one of the means of improving their lifetime, which means decreasing traffic environmental impact. In order to understand how tyres behave and to predict the real-time tyre-road coefficient of friction, which is strongly influenced by the temperature, in the last few years several complex thermo-mechanical models of heat transfer inside the tyre have been developed. However, in the current state of the art of the literature and practice, there is still an important parameter regarding such models that is not deeply studied. This parameter is the heat transfer coefficient between the tyre and the road at the contact patch, which usually is considered as a constant. The current research paper allows understanding that such an approximation is not always valid for all of the speeds and tyre loads of city and race cars; instead, it is developed an equation that, for the first time, calculates the real-time, dynamic tyre-road heat transfer coefficient, taking into account the tyre's travelling speed and the footprint length. The equation results are in good agreement with the empirical values coming from the literature and permit understanding how much such a parameter can vary, depending on the tyre use range. The formulation is simple enough to be easily implemented in existing thermodynamic tyre models without requiring meaningful computational time.
... SBS is well known for its ability to improve the elasticity of a binder at high temperatures and its adaptability at cold temperatures [11,13,21]. In order to increase the compatibility of guss mastic asphalt, this SBS modifier can strengthen the hightemperature performance of an asphalt mix by lowering the mixing temperature and the viscosity of high-temperature asphalt [1,20,22]. The proposed bitumen exhibits greater resilience to low-temperature cracking and also to rutting at greater temperatures than normal asphalt. ...
... SBS is well known for its ability to improve the elasticity of a binder at high temperatures and its adaptability at cold temperatures [11,13,21]. In order to increase the compatibility of guss mastic asphalt, this SBS modifier can strengthen the high-temperature performance of an asphalt mix by lowering the mixing temperature and the viscosity of high-temperature asphalt [1,20,22]. The proposed bitumen exhibits greater resilience to low-temperature cracking and also to rutting at greater temperatures than normal asphalt. ...
Conventional hot mix asphalt overlaying on trench infrastructure typically necessitates extended cooling times for further works and can have adverse effects on buried components, such as electricity cables and hot water pipes. Therefore, this research aims to investigate the use of warm guss mastic asphalt (at an installation temperature of 160 °C) as an overlaying material for mini-trenches, which can reduce the cooling time required for traffic opening and improve the efficiency of the construction process. This research involved two stages: first, lab testing and related research results were used to generate the thermal conductivity and specific heat necessary for simulation work. Second, a finite element model analysis was conducted to evaluate the thermal transmission of the overlaying surface and the buried conduit based on the summer pavement temperature distribution through the Korean Pavement Research Program. Afterward, the field test bed was constructed to verify the simulation. The results indicate that the optimal thickness of the overlaying material and the concrete covering should be designed to ensure thermal durability and meet traffic opening requirements. The overlaying depth of the mini trench using warm mix guss mastic asphalt should be less than 100 mm to meet with the traffic opening time, while the thickness of the concrete covering should be designed to be more than 100 mm to ensure thermal durability. Additionally, the findings suggest that the application of warm guss asphalt could reduce the opening time by 30 min to 1 h and 25 min compared to conventional hot guss asphalt materials. When the pavement surface temperature for the traffic opening is controlled at 50 °C, the asphalt mixture requires at least 2 h to 5 h to meet the cooling criteria for traffic opening, respectively. Overall, this research confirms the potential benefits and optimal use of warm guss mastic asphalt in the construction process of mini-trenches.
... Thermal properties of asphalt concrete have been investigated by many researchers with emphasis on the influencing variables that affect the thermal behavior of asphalt mixtures. This is demonstrated in studies conducted by Mrawira and Luca (2006); Kim et al. (2003); Côté & Konrad (2005); Çanakci et al. (2007); Hall & Allinson (2009); (Pan et al., 2017); (Hassn et al., 2016); (Bai et al., 2015); (Tang et al., 2014); and (Wang et al., 2016). ...
The main objective of this paper is to develop predictive models using Beta regression for laboratory-prepared hot mix asphalt (HMA) specimens' thermal properties, including thermal conductivity (TC), thermal diffusivity (TD) and specific heat (SH). Thirty such specimens were prepared while varying the mixture's nominal maximum aggregate sizes (NMAS) and gradation coarseness. The widely used Transient Plane Source (TPS) method was employed to determine the thermal properties of the asphalt concrete. Only one type of asphalt binder was used for preparing all specimens. The air void volume (Va) and the effective binder volume (Vbe) were calculated for each mixture. To this end, the multiple linear regression and the nonlinear Beta regression were employed. Laboratory work resulted in hundred and fifty (150) data points. Three nominal maximum aggregate sizes, two gradation coarseness levels, five replicates and five different locations of measurements to ensure accuracy and repeatability in the obtained results. In conclusion, using Va and Vbe as predictors provided reliable predictive models for the thermal properties of different asphalt mixtures. The distribution of Va and Vbe was identified, and synthetic data were created to evaluate the accuracy of the models. Apart from R 2 values, Beta regression was more reliable to predict thermal properties of asphalt mixtures than multiple linear regression.
... Utilizing mineral aggregates and conductive fillers is an effective way to produce conductive asphalt mixes. There was no visible variance between the asphalt concrete's thermal characteristics before and after ageing [17]. Norambuena-Contreras et al. (2018) investigated the impact of metallic waste on the thermophysical capabilities of asphalt mixes. ...
Conductive hot-mix asphalt is recommended for enhancing the solar energy collection performance of an asphalt solar collector. This type of collector consists of embedded tubes with circulating water or air inside pavement construction to generate power. This work intends to shed light on the selection of novel components for the preparation of conductive asphalt mixes. Lee's disc method was used to determine the thermal conductivity of this composite material. A comprehensive examination was conducted to prepare reference and conductive asphalt discs by manufacturing asphalt mixtures in a laboratory specified for this work. New Iraqian natural resource materials, including quartzite sandstones and silica sands, and Iraqian industrial waste materials, such as slag stones, steel wool fibres and metallic waste powder, were employed as conductive components. The results showed that the conductive materials increase the thermal conductivity of the reference asphalt mixture up to 42.75% and 66.65% for quartzite and slag combinations, respectively. Slag aggregates should not be utilized as conductive material in asphalt mixes without increasing the binder ratio. Proportions of 4% and 38% of steel wool fibres and metallic waste powder additives, respectively, were found to produce the optimal results for thermal conductivity enhancement. The air void contents and fracturing ratio of conductive discs were decreased when using conductive novel components, which is an indication of the importance of current findings in improving asphalt mixtures in heat storage and transfer applications.
... Utilizing mineral aggregates and conductive fillers is an effective way to produce conductive asphalt mixes. There was no visible variance between the asphalt concrete's thermal characteristics before and after ageing [17]. Norambuena-Contreras et al. (2018) investigated the impact of metallic waste on the thermophysical capabilities of asphalt mixes. ...
Conductive hot-mix asphalt is recommended for enhancing the solar energy collection performance of an asphalt
solar collector. This type of collector consists of embedded tubes with circulating water or air inside pavement
construction to generate power. This work intends to shed light on the selection of novel components for the
preparation of conductive asphalt mixes. Lee’s disc method was used to determine the thermal conductivity of
this composite material. A comprehensive examination was conducted to prepare reference and conductive
asphalt discs by manufacturing asphalt mixtures in a laboratory specified for this work. New Iraqian natural
resource materials, including quartzite sandstones and silica sands, and Iraqian industrial waste materials, such
as slag stones, steel wool fibres and metallic waste powder, were employed as conductive components. The
results showed that the conductive materials increase the thermal conductivity of the reference asphalt mixture
up to 42.75% and 66.65% for quartzite and slag combinations, respectively. Slag aggregates should not be
utilized as conductive material in asphalt mixes without increasing the binder ratio. Proportions of 4% and 38%
of steel wool fibres and metallic waste powder additives, respectively, were found to produce the optimal results
for thermal conductivity enhancement. The air void contents and fracturing ratio of conductive discs were
decreased when using conductive novel components, which is an indication of the importance of current findings
in improving asphalt mixtures in heat storage and transfer applications.
... Several researchers [7][8][9][10][11][12][13][14][15][16] have investigated several factors that influence the thermal properties of asphalt concrete such as aggregate type, gradation type (G), compaction level, moisture content, air voids, and conductive fillers (such as graphite, carbon black, and lastly carbon fiber). In addition, other researchers have demonstrated the implementation of soft technological techniques such as Artificial Intelligence (AI), Artificial Neural Network (ANN) and Machine Learning (ML) capabilities in studies of asphalt pavement materials to predict parameters related to flexible pavement in order to reduce time and effort during laboratory tests and consequently cost [17][18][19][20][21][22][23][24]. ...
... The results showed that the asphalt mixtures with higher air voids volume have lower thermal conductivity and specific heat and this finding is in agreement with [7,12,13,39]. The results also showed that the gradation coarseness had an effect on thermal conductivity. ...
... In the present study, asphalt content has been found to affect thermal properties; specific heat and thermal conductivity increase as the asphalt content increases, this finding varies from the result in reference [12], which indicated that there is no evidence of the effect asphalt binder content on thermal properties due to its low proportion. ...
The objective of this study is to investigate the impact of aggregate gradation and Superpave volumetrics on thermal properties of asphalt mixtures. Thirty asphalt concrete specimens with three different Nominal Maximum Aggregate Sizes (NMAS) of 19.0, 12.5 and 9.5 mm and two levels of gradation coarseness: fine gradation (FG) and coarse gradation (CG) were prepared. The Transient Plane Source (TPS) method was used to determine thermal properties. Based on the analyses performed, it was concluded visually that heat transfer is highly dependent on the contact area which, in turn, is related to air void volume. Unlike NMAS, the gradation coarseness (G) has some effect on thermal conductivity (TC) (p-value = 0.008 < 0.05). On the contrary, the NMAS, unlike gradation coarseness, has a significant effect on thermal diffusivity (TD) with a p-value of 0.025. Both gradation coarseness and NMAS have a significant effect on thermal diffusivity (p-value = 0.029 < 0.05) and do not have much effect on specific heat (SH) where p-value is greater than 0.05. Nevertheless, it was noticed that the thermal diffusivity increased linearly with an increase in aggregate size from 85.64 mm²/s to 125.79 mm²/s at 9.5 NMAS FG and 19 mm NMAS FG, respectively. Whereas the specific heat and thermal conductivity increase as the asphalt content (AC) increases. Consequently, the highest average values of thermal conductivity and specific heat are 2 W/m.K and 0.025 M.J/m³.K, respectively, at the highest asphalt content of 6.1%. Multiple linear regression, non-linear regression and deep learning (MLR, NLR and DL) equations were developed. The non-linear regression resulted relatively in the best predictive power of all equations. Finally, larger datasets are needed to predict thermal properties with higher confidence.
