Surface Temperature Of Asphalt Research Articles

Mechanical Testing Methods for Evaluating Thermoplastic Permanent Pavement Markings

The durability of permanent pavement markings (PPMs) on roadways is important for drivers’ safety. There are two primary mechanical failure modes: cohesive failure that occurs internally in PPMs through small defects, such as internal pores, and adhesive failure that occurs along the interface between PPMs and road surfaces. Thus, it is critical to characterize the intrinsic mechanical properties of PPMs as well as the adhesion of PPMs on road surfaces to understand their mechanical performance and, ultimately, the durability of PPMs. In this study, the flexural modulus and strength of PPMs were characterized via three-point bend testing, while fracture toughness was determined with single edge notch bend testing. To analyze the adhesive performance of PPMs on asphalt, a shear adhesion testing approach was developed to measure the apparent debonding energy of PPM specimens on asphalt. The shear adhesion test was performed on asphalt road surfaces and cut surfaces to investigate the chemical and mechanical interfacial effects on adhesion. Two commercial thermoplastic PPMs with different mechanical properties were investigated to study how various factors directly affect the adhesion of PPMs on asphalt surfaces. Through mechanical tests, the relationships between the intrinsic materials properties and the mechanical performance of PPMs on asphalt were studied. A PPM material that had lower modulus and higher deformation energy exhibited greater adhesion performance on asphalt, especially when the PPM material was applied at higher asphalt surface temperatures on rough asphalt surfaces.

Effects of Albedo and Thermal Inertia on Pavement Surface Temperatures with Convective Boundary Conditions—A CFD Study

The urban heat island (UHI) effect increases the ambient temperatures in cities and alters the energy budget of building materials. Urban surfaces such as pavements and roofs absorb solar heat and re-emit it back into the atmosphere, contributing towards the UHI effect. Over the past few decades, researchers have identified albedo and thermal inertia as two of the most significant thermal properties that influence pavement surface temperatures under a given solar load. However, published data for comparisons of albedo and thermal inertia are currently inadequate. This work focuses on asphalt and concrete as two important materials used in the construction of pavements. Computational fluid dynamics (CFD) analyses are performed on asphalt and concrete pavements with the same dimensions and under the same ambient conditions. Under given conditions, the pavement top surface temperature is evaluated with varying albedo and thermal inertia values. The results show that the asphalt surface temperatures are consistently higher than the concrete surface temperatures. Surface temperatures under solar load reduce with increasing albedo and thermal inertia values for both asphalt and concrete pavements. The CFD results show that increasing the albedo is more effective in reducing pavement surface temperatures than increasing the thermal inertia.

An infrared thermography-based study on the variation in diurnal and seasonal land surface temperature at Dibrugarh city, India

The understanding of surface urban heat island pattern above Dibrugarh City has been studied through in situ observation using non-contact infrared thermometer for a period of 4 months by covering 16 selected locations. The chosen locations envelop both urban and suburban sites. The study draws attention to urban hot spots toward the central part of the city all through the different months in addition to the seasons, owing to heat retention supported by the built environment with fewer vegetation cover. Seasonally winter uncovered utmost variability of LST indicated by higher CV value. The core locations/sites witnessed a least amount of variability and continuity of higher LST throughout the learning months. At diurnal pattern, LST designated a sharp decrease from morning to afternoon period through winter months, while contrastingly summer months witnessed a sharp fall of LST from afternoon to night period. Among all the surfaces, asphalt pavement noticed maximum surface temperature with maximum variability in both diurnal and temporal scales. Maximum assimilation with fewer albedo of asphalt surface along with drier soil and grass comes across maximum LST in the internal part of the city. In addition, traffic, pollution and anthropogenic heat emission supported warmer surface temperature of asphalt, grass and bare soil, which on the whole put into the growth of higher surface heat. The stronger affirmative correlation coefficient amid the temperature of different surfaces with air temperature and comparatively weaker unconstructive correlation with relative humidity witnessed the dominant role of air temperature on overall surface urban heat island process.

The application of sulfur-asphalt concrete with modifiers in the climatic conditions of Vietnam

The paper considers the influence of ambient temperature and other weather factors on the properties of traditional asphalt concrete in Vietnam. The advantages of sulfur-extended asphalt concrete with modifiers containing neutralizers for the emission of toxic gases are presented to increase the quality and life of roads and solve the environmental problem of using sulfur-extended asphalt concrete. For calculating the surface temperature of asphalt concrete from the ambient temperature, the method of Yu. N. Kovalev is used (Russia). The weather data for January and July 2015, taken from the hydrometeorological stations of the cities of the respective zones in Vietnam, are used for calculations. The paper presents an experimental setup for determining the intensity of toxic gases evolution and the effect of neutralizers. The widespread introduction in the practice of building progressive environmentally friendly sulfur-containing materials: sulfur-extended asphalt concrete with modifiers, containing toxic gases emission neutralizers, which have higher physical and mechanical properties (wear resistance, etc.) compared to traditional ones at less or equal cost, can open up opportunities to increase quality and lifetime of roads in Vietnam.

THERMAL ANALYSIS OF URBAN LAND COVER USING AN UNMANED AERIAL VEHICLE (UAV) IN MEDELLIN, COLOMBIA

Thermal anomalies in built environments, known as Urban Heat Islands (UHI), are studied with satellite-derived data. However, this information is insufficient to examine regions such as the Aburra Valley, where the city of Medellin is located. In this valley, atmospheric interferences are common and the rugged terrain influences the amount of solar radiation reaching the surface, which hinders the analysis of the UHI. Unmanned Aerial Vehicles (UAVs) can be used to obtain the Land Surface Temperature (LST) at a time and location that is more convenient. In this project, a UAV was equipped with a thermal sensor to collect data on natural (ground vegetation and trees) and artificial (concrete, asphalt, and clay roof tiles) land cover types in Medellin, Colombia. The thermal information provided by the drone overcame the limitations of the satellite-derived data in terms of spatial, temporal, and radiometric resolution. This data enabled the study of specific land-cover types in different urban contexts, especially the influence of vegetation on LST. The findings suggested that the distribution of trees is crucial for UHI mitigation. Tree shading reduced the surface temperature of asphalt in average by 12 °C and by 5.7 °C for concrete. In addition, the presence of trees alongside streets reduced the maximum surface temperature of asphalt by 22.4 °C in the same neighborhood. These results contributed to the understanding of the influence of urban development on Medellin’s temperature.

THERMAL ANALYSIS OF URBAN LAND COVER USING AN UNMANED AERIAL VEHICLE (UAV) IN MEDELLIN, COLOMBIA

Thermal anomalies in built environments, known as Urban Heat Islands (UHI), are studied with satellite-derived data. However, this information is insufficient to examine regions such as the Aburra Valley, where the city of Medellin is located. In this valley, atmospheric interferences are common and the rugged terrain influences the amount of solar radiation reaching the surface, which hinders the analysis of the UHI. Unmanned Aerial Vehicles (UAVs) can be used to obtain the Land Surface Temperature (LST) at a time and location that is more convenient. In this project, a UAV was equipped with a thermal sensor to collect data on natural (ground vegetation and trees) and artificial (concrete, asphalt, and clay roof tiles) land cover types in Medellin, Colombia. The thermal information provided by the drone overcame the limitations of the satellite-derived data in terms of spatial, temporal, and radiometric resolution. This data enabled the study of specific land-cover types in different urban contexts, especially the influence of vegetation on LST. The findings suggested that the distribution of trees is crucial for UHI mitigation. Tree shading reduced the surface temperature of asphalt in average by 12 °C and by 5.7 °C for concrete. In addition, the presence of trees alongside streets reduced the maximum surface temperature of asphalt by 22.4 °C in the same neighborhood. These results contributed to the understanding of the influence of urban development on Medellin’s temperature.

Leveraging Intelligent Compaction and Thermal Profiling Technologies to Improve Asphalt Pavement Construction Quality: A Case Study

Intelligent compaction (IC) is an emerging technology with rollers equipped with global navigation satellite system (GNSS), an accelerometer-based measurement system, and an onboard color-coded display for real-time monitoring and compaction control. Paver-mounted thermal profiling (PMTP) is used to monitor asphalt surface temperatures behind a paver with a thermal scanner, and to track paver speeds, stops, and stop durations. Leveraging both IC and PMTP technologies allows for paving and compaction controls in real time, and for executing appropriate adjustments as needed. A case study is used to demonstrate the advantage of using both IC and PMTP over conventional operations. Postconstruction asphalt coring and tests, as well as pavement profile surveys were conducted to provide asphalt density data and pavement smoothness acceptance data for comparison and correlation analysis with IC and PMTP data. The data from 2 days of operations, one without the Material Transfer Vehicle (MTV) and another with the MTV, were analyzed and compared to illustrate the benefits of using IC, PMTP, and MTV for producing quality pavement products. Durability and smoothness are two key construction qualities for agencies and users of hot mix asphalt (HMA) pavements. These two factors also affect the long-term structural and functional pavement performance.

Analyses of urban pavement surface temperatures

Heat islands are areas that have higher air temperatures than their surroundings. It has been proven that the use of certain types of pavement surface materials contributes to the occurrence of heat islands. The heat island effect is dominant in urban areas, mainly in city centres. To identify potentially favourable pavement surface materials that are suitable for the use on surfaces in urban areas, an extensive analysis of in-place material temperatures was conducted in the city centre of Rijeka (Croatia) during the summer of 2011 and 2012. The measurements included temperatures of pavement surfaces made of asphalt, concrete and stone. The analysis results identified local materials whose use help to reduce or mitigate the effect of additional heating in the urban environment caused by emission of heat from pavement surfaces. In terms of additional heating of urbanized areas, asphalt has proven to be significantly less favourable than other analysed materials. In addition to the materials selected for the use in wearing courses, their characteristics and the microclimates of the locations where they will be placed must be taken into consideration. Among the standard paving materials, in terms of heating and temperature, concrete is more favourable than asphalt because the differences between concrete surface temperatures and air temperatures are significantly smaller than between asphalt surface temperatures and air temperatures. Stone surfaces have proven to be the most favourable. The analysis results presented can be used to establish clear guidelines for using specific materials under specific conditions.

Innovative thermochromic asphalt coating: characterisation and thermal performance

Conventional asphalt strongly absorbs the energy from sunlight due to its black colour. The induced high surface temperature on asphalt pavement during summer and fast temperature drop during winter accelerate the rutting and cracking, impairing its long-term durability. Thermochromic materials, substances that can reversibly change their colours in response to temperature, are characterised as high solar reflectance above certain threshold temperature and high absorbance below the threshold temperature. In this paper, innovative thermochromic coatings are designed to modulate the surface temperature of asphalt pavement and potentially improve its durability and safety. The thermal, optical, and chemical properties of the coatings with thermochromic materials were characterised using modulated differential scanning calorimetry, thermogravimetric analysis, UV–Vis–IR spectrophotometry, and Fourier transform infrared spectroscopy, respectively. Besides, production conditions of thermochromic asphalt coatings were also determined to prevent thermal degradation. Finally, the thermal performance of thermochromic asphalt coatings was evaluated by measuring the surface temperature under different weather conditions. Results of measurements under hot weathers found that the surface temperature of thermochromic asphalt coating is lower than that of the conventional asphalt coating with the maximum decrease as high as 6.6°C. This helps to improve its resistance to high temperature-related performance degradation (such as rutting and fatigue). Furthermore, experimental results during cold weathers indicated that the surface temperature of asphalt concrete covered with thermochromic asphalt coating is generally 1°C higher than that of conventional asphalt coating. This means thermochromic asphalt can potentially delay ice formation on the surface of the road than traditional asphalt. Therefore, the incorporation of thermochromic materials into asphalt pavement will potentially help improve the durability, reduce undesirable environmental impacts, and improve the safety of asphalt roads.

Thermal Characteristics of Stormwater Runoff from Asphalt and Sod Surfaces1

Abstract: Urban impervious surfaces absorb and store thermal energy, particularly during warm summer months. During a rainfall/runoff event, thermal energy is transferred from the impervious surface to the runoff, causing it to become warmer. As this higher temperature runoff enters receiving waters, it can be harmful to coldwater habitat. In an urban watershed, impervious asphalt surfaces (roads, parking lots, and driveways) and pervious residential lawns comprise a significant portion of the watershed area. A paired asphalt‐turfgrass sod plot was constructed to compare the thermal runoff characteristics between asphalt and turfgrass sod surfaces, to identify meteorological variables that influence these thermal characteristics, and to evaluate evaporative heat loss for runoff from asphalt surfaces. Rainfall simulations were conducted during the summers of 2004 and 2005 under a range of climatic conditions. Asphalt surface temperatures immediately prior to rainfall simulations averaged 43.6°C and decreased an average of 12.3°C over 60 min as rain cooled the surface. In contrast, presimulation sod surface temperatures averaged only 23.3°C and increased an average of 1.3°C throughout the rainfall events. Heat transferred from the asphalt to the runoff resulted in initial asphalt runoff temperatures averaging 35.0°C that decreased by an average of 4.1°C at the end of the event. Sod runoff temperatures averaged only 25.5°C and remained fairly constant throughout the simulations. Multivariable regression equations were developed to predict (1) average asphalt surface temperature (R2 = 0.90) and average asphalt runoff temperature (R2 = 0.92) as a function of solar radiation, rain temperature, and wind speed, and (2) average sod surface temperature (R2 = 0.85) and average sod runoff temperature (R2 = 0.94) as a function of solar radiation, rain temperature, rain intensity, and wind speed. Based on a heat balance analysis, existing evaporation equations developed from studies on lakes were not adequate to predict evaporation from runoff on a heated impervious surface. The combined heat from the asphalt and sod plots was an average of 38% less than the total heat had the total area consisted solely of asphalt.

Urban tree transpiration over turf and asphalt surfaces

We used a two-layer canopy model to study transpiration of tree species as affected by energy-balance properties of a vegetated and paved surface. During several dawn-to-dusk studies, tree transpiration, stomatal conductance, leaf temperature (T l ), and several microclimate variables, were measured over turf and an asphalt surface. Cumulative transpiration was estimated from a leaf energy-balance equation applied to a tree crown apportioned between sunlit and shaded layers. Afternoon asphalt surface temperatures ( T s) were 20–25°C higher than turf T s in all studies. Air-temperature differences between sites were minimal due to the size and proximity of the two surfaces that resulted in mixing of air. Trees over asphalt had consistently higher T, than those over turf, apparently due to interception of the greater upwards long-wave radiation flux from higher T l . In one study flowering pear over asphalt in a humid environment bad higher T l resulting in one-third more total water loss compared to trees over turf. In other studies, however, water loss of green ash and Norway maple over asphalt in an arid environment was either equal to or less than that over turf. Less water loss was due to higher T l over asphalt causing prolonged stomatal closure. Model manipulation indicated that tree water loss over asphalt will depend on the degree of stomatal closure resulting from how interception of increased energy-fluxes and ambient humidity affect leaf-to-air vapor pressure differences.

Seasonal Variation of Backcalculated Subgrade Moduli

Seasonal variations in pavement material properties and behavior due to variations in temperature and moisture conditions are known to affect the structural performance of pavement. Temperature, subgrade moisture content, and falling weight deflectometer (FWD) deflection data were collected monthly on four asphalt pavement test sections for a year. Subgrade moduli were backcalculated using the elastic layer theory with two calculation schemes and pavement models. Backcalculation of subgrade moduli by subdividing the subgrade into a compacted subgrade layer and a natural soil subgrade layer resulted in compacted subgrade moduli that are more sensitive to the seasonal variation for all sites. It was found that for almost all sites, the patterns of subgrade response, in terms of subgrade moduli versus subgrade moisture content, simulated sine-shaped forms signifying a temperature effect. The temperature effect was confirmed by the strong correlation between backcalculated subgrade moduli and pavement surface temperature during FWD tests. The lowest backcalculated subgrade moduli were obtained for two sections during months when asphalt surface temperatures were excessively high (greater than 40°C). Both backcalculation schemes showed similar trends in variation of subgrade moduli over seasons. When the AASHTO relative damage concept was used to compute the effective roadbed soil resilient modulus for design, similar values were found for both schemes for most of the sites. The minimum frequency of FWD testing to capture the seasonal variation of subgrade was found to be three tests per year, or testing every fourth month, assuming that unusually high temperature regimes could be avoided.