Influence of the Thermophysical Properties of Pavement Materials on the Evolution of Temperature Depth Profiles in Different Climatic Regions

Abstract

14The paper summarizes the relative influence of different pavement thermo-physical properties on the 15 thermal response of pavement cross-sections, and how their relative behaviour changes in different 16 climatic regions. A simplified one-dimensional heat flow modelling tool was developed to achieve this 17 using a finite difference solution method for studying the dynamic temperature profile within 18 pavement constructions. This approach allows for a wide variety and daily varying climatic 19 conditions to be applied, where limited or historic thermo-physical material properties are available, 20 and permits the thermal behaviour of the pavement layers to be accurately modelled and modified. 21The model was used with available thermal pavement materials properties and with properties 22 determined specifically for the study reported here. The pavement materials included in the study 23 comprised both conventional bituminous and cementicious mixes as well as unconventional mixtures 24 that allowed a wide range of densities, thermal conductivities, specific heat capacities and thermal 25 diffusivities to be investigated. Initially, the model was validated against in-situ pavement data 26 collected in the USA in five widely differing climatic regions. It was found to give results at least as 27 good as others available from more computationally expensive approaches such as 2D and 3D FE 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 commercial packages. Then the model was used to compute the response for the same locations had 29 the thermal properties been changed by using some of the unconventional pavement materials been 30 used. This revealed that reduction of temperature range by several degrees was easily possible (with 31 implications for reduction of rutting, fatigue and the Urban Heat Island effect) and that depth of 32 penetration of peak temperatures was also achievable (with implications for winter freeze-thaw). 33 However, the results showed that there was little opportunity to displace the peak temperatures in 34 time. T dp dew-point temperature (˚C)28 Manuscript Click here to download Manuscript: Hall et al 2010 -temp profile pavement material-R2 version.doc 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 54T 0 absolute temperature of the surface (K) 55T m temperature at nodal point m (K) 56 1

Impact of heat advection on the thermal regime of roads built on permafrost

“…In northern regions, transportation infrastructure experiences severe structural damage due to the degradation of the underlying permafrost (Hjort et al, ), leading to large increases in maintenance costs and reductions in the lifespan of road embankments (Cheng, ; Reimchen, Doré, Fortier, & Walsh, ). The temperatures within a road embankment's sub‐base (i.e., a layer of fill material) and subgrade (i.e., native material under an embankment) are a function of air temperature, atmospheric radiation, wind convection, and heat conduction through the embankment material (Dumais & Doré, ; Hall, Dehdezi, Dawson, Grenfell, & Isola, ; Zhang, Wu, Liu, & Gao, ). The thermal regime of infrastructure can be modified and cooled by mitigation techniques used in or on the embankment (Chen, Yu, Yi, Hu, & Liu, ; Doré, Niu, & Brooks, ; Goering & Kumar, ; Lai, Zhang, Zhang, & Mi, ).…”

Energy harvesting from pavements and roadways: A comprehensive review of technologies, materials, and challenges

“…Future studies should also focus on location‐specific feasibility, and use of numerical modeling and simulation tools to effectively analyze the harvester performance. There are many specific issues related to different areas, which could be addressed in future researches, as categorized below: Solar PV panel road: The safety issues posed by the skid resistance, uninterrupted power generation, storage, adaptability to the pavement, and affordability. ASCs/AHPs: Integrity of the pavement‐pipe structure, durability, refurbishment, pipe‐size, pipe‐spacing, pipe‐arrangement, constructability, cost, thermo‐fluidic and thermo‐physical characteristics of the harvesting unit and pavement under varying climatic and operating conditions (similar to the work of Hall et al), and techno‐economic feasibility of ASCs with air as the heat exchanging fluid. TEG: Improving the power output by extended research on the PP‐TEG system, and also by integrating with other solar energy harvesting techniques. PEHs: Harmony with the pavement material, fatigue failure due to cyclic loading, cost, storage, maintenance, multi‐stacking, improved Cymbal structures such as DPEHC, and sustainability. EHRSAs: Minimizing frictional and other losses, use of more efficient magnets, use of full‐scale vehicle model for analysis, trade‐off between energy harvesting efficiency, damping performance, vehicle dynamics and ride comfort, robustness, efficient motion transmission and rectifying mechanisms, novel power generation circuits, and affordability. Geothermal: Environmental impact in terms of waste disposal, air quality, water quality, biological resources, geologic hazards, noise, and land use issues; feasibility of new techniques such as SFHP and GCHAP. Rainwater: Feasibility of rainwater harvesting to work with techniques such as GSHP in the perspective of energy recovery from pavements. Hybrid: Combinations such as piezo‐pyro, piezo‐solar panel and TEG‐pyro, the idea of “Green Roadway” that combines solar, wind and geothermal techniques, and various other viable combinations for better efficiency and real implementation. Zhao et al analyzed the potential challenges of implementing hybrid solar‐wind system on highways, which would guide future researchers. Others: Triboelectric and electrochemical techniques, the Hernández's idea of exploiting gravitational force, intelligent tires, the SPM microgenerator, and energy harvesting from pedestrians, bridges, and railways. Materials: Optimization of thermophysical properties of pavement materials, incorporation of PCMs in pavements, lead‐free and organic piezo‐electric materials, PMN‐PT and PZN‐PT single crystals, polymer‐based materials such as PVDF and its copolymers, LiTaO 3 crystals and triglycine for pyroelectric generation, CFRCs and graphite/cement‐based composites for TEG, and development of new materials both for pavements and energy harvesters. Nano materials: Cement‐carbon nano‐composites with higher content of carbon fiber for pyroelectric generation, coating of PZTs with nanocomposite comprising ferrofluid, ZnO and epoxy binder, use of metal oxide semiconductor nanowires for piezoelectric generation, blending of flexible polymer‐based composite materials with nanomaterials, and use of nanofluids to enhance the heat transfer performance of ASCs.…”

Enhancing thermal properties of asphalt materials for heat storage and transfer applications

“…The model is accurate to within 2ºC variation, and was found to give results at least as accurate as other similar models (Yavuzturk, Ksaibati et al 2005;Gui, Phelan et al 2007). The details of the model and its validation can be found in (Keikhaei, Hall et al 2010;Hall, Keikhaei Dehdezi et al 2012) and a brief description is given here.…”