Parametric analysis of energy harvesting pavements operated by air convection

In this paper, an energy harvesting pavement prototype using air as the operating fluid is described and analysed. The prototype harvests the thermal energy available in the pavement through pipes embedded in its structure, where air flows thanks to natural convection. The air is able to exit the system through an updraft chimney. A parametric analysis of the controllable parameters of interest is performed in this work in order to evaluate the variation in the performance of the energy harvesting prototype in different experimental setups. This study shows that there exists a maximum value for the air speed in each configuration and that the energy harvesting efficiency depends on the height and the diameter of the chimney. Moreover, there is a minimum value of the chimney diameter that does not allow air movement and makes the whole system behave as if no pipes were embedded in the pavement structure

Laboratory Performance Evaluation of a Gap-Graded Asphalt-Rubber Mixture in Puerto Rico

ABSTRACT. Implementation of new technologies involvin

SELECTION OF LONG LASTING REHABILITATION TREATMENT USING LIFE CYCLE COST ANALYSIS AND PRESENT SERVICEABILITY RATING

A wide range of variables influence the selection strategy for rehabilitation and maintenance of pavements. The focus of this study is to conduct a project-level evaluation of high traffic volume asphalt-surfaced pavements located in the state of Oklahoma and develop a performance based rehabilitation strategy. In order to develop feasible rehabilitation strategies, a systematic collection of relevant pavement-related data was provided by ODOT. The collected data includes performance measurements, traffic, climate and structural integrity of existing pavements obtained by falling weight deflectometer (FWD) analysis. These various data sets are supplemented with laboratory testing to determine the material characterization and damage characterization of different surface rehabilitation mixtures. The national highways located in the state of Oklahoma are divided in several pavement family groups. The representative pavement sections for family groups are identified and the required data for analysis are either extracted from existing sources or measured in the laboratory. Three levels of rehabilitation activities including light, medium and heavy rehabilitation are considered for each of the pavement family groups and a mechanistic-empirical methodology is employed to obtain an estimate of the performance of potential rehabilitation activities and their extended service life. A combination of local material properties, structural integrity and environmental condition are used for structural analysis and development of an evaluation output matrix. At the end of this study a series of time-based renewal solutions are recommended for pavement family groups with a similar existing condition and the most cost effective methodology is determined by performing life cycle cost analysis using RealCost software.Final report, November 2013-October 2015N

Summary of Case Studies and Observations on Airport Experience with Pavement Surface Treatments

The Federal Aviation Administration Airport Technology Research and Development Branch sponsored a study of pavement surface treatments with two main objectives: to identify best practices and to propose guidance for selecting surface treatments as the appropriate treatment strategy for airport pavements. Twelve airports and agencies with surface treatment experience provided information to develop case studies. Site visits were made to 11 airports, associated with 8 of the case studies, to collect additional information. This technical note summarizes key observations regarding the use of surface treatments at different airports and on different features based on those case studies. Complete case studies are included as an appendix

Thermal properties of asphalt pavements under dry and wet conditions

Air voids play an important role in the temperature evolution of asphalt pavements exposed to the sun's radiation and the environment, but their effects have never been precisely quantified before. The objective of this article is to understand and quantify the effect of air voids on the temperature evolution of asphalt mixture under dry and wet conditions. To achieve this objective, dry and saturated asphalt slabs with different air voids contents have been exposed to infrared light and the surface and bottom temperature evolution, heat flux and evaporation rate have been measured. It was observed that under dry conditions air voids simply affect the specific heat capacity and thermal conductivity of asphalt mixture, while under wet conditions the energy used by water for evaporation reduces drastically the temperature of asphalt mixture. This has significance for Urban Heat Island mitigation amongst other implications

Effect of air voids content on thermal properties of asphalt mixtures

Air voids content is considered as one of the factors that may affect heat transfer through asphalt mixture, although their specific role on the asphalt mixture temperature is still unclear. The objective of this research is to have a deep insight of the effect of air voids content on the temperature evolution, transport and storage of heat in asphalt mixture under dry conditions. With this objective, asphalt mixture slabs with different air voids content have been built and their thermal conductivity, specific heat capacity, light absorptivity and thermal diffusivity related to their temperature evolution have been measured when they are exposed to infrared light and during the cooling process. It was observed that asphalt mixture with high air voids content exhibited slightly higher steady state temperatures than denser asphalt mixture and that the heating and cooling rates are higher in porous asphalt mixture than in denser materials. The reason for the faster increase and decrease in temperature of porous mixture and for the higher temperature reached by porous asphalt is its lower specific heat capacity and thermal conductivity. Finally, it could be observed that the connectivity of air voids in asphalt mixture did not play an important role on the temperature reached by asphalt mixture