2013 Session: 292

• Durability Quantification for TiO2 Photocatalytic Concrete and Asphalt Pavements
  Abstract: The use of nano sized titanium dioxide in photocatalytic pavements to combat air pollution has received considerable attention in recent years. Past research focused on the effects of environmental and operational parameters on photocatalytic efficiency and its performance under laboratory and field conditions. Few studies have attempted to quantify the durability of the technology integrated with in-service photocatalytic pavements. This study developed and implemented a new photocatalytic quantification method used to quantify the short term durability of a TiO2 spray application on two pavement surfaces: concrete and asphalt. This was accomplished through developing a nitrate extraction method that could be used on in-service pavements without requiring core extraction. Results of the proposed method were compared to results obtained from the Japanese Industrial Standards: JIS R 1701-1. The experimental program included testing photocatalytic samples in the laboratory for NOx reduction and nitrate accumulation based on JIS R 1701-1. Results were compared to the nitrate accumulation using the proposed method and a correction factor was developed. The developed method was then used to quantify the durability of a TiO2 treated photocatalytic pavement over a five-month monitoring period under field conditions. Results showed that the durability of TiO2 in concrete and asphalt pavements is predicted to be 10 and 14 months, respectively.
  Authors: Osborn, David; Hassan, Marwa M.; Asadi, Somayeh; White, John R
  Authors: Osborn, David; Hassan, Marwa M.; Asadi, Somayeh; White, John R
  Year: 2013
  Document Type: Paper
  Subject: Environment; Materials; Pavements
  Session: 292
  Paper Number: 13-0901
• Using Artificial Intelligence Models to Evaluate Field Performance of Photocatalytic Asphalt Pavement for Ambient Air Purification
  Abstract: In recent years, the application of titanium dioxide (TiO2) as a photocatalyst in asphalt pavement has received considerable attention due to its ability to purify ambient air from traffic-emitted pollutants via photocatalytic processes. The objective of this study was to utilize Artificial Neural Network (ANN) and Neuro-Fuzzy (NF) models to predict NOx concentration in the air as a function of traffic count (Tr) and climatic conditions including humidity (H), temperature (T), solar radiation (S), and wind speed (W) before and after the application of TiO2 on the pavement surface. A field study was conducted where a water-soluble nano TiO2 solution was sprayed on a 0.2 mile of asphalt pavement in Baton Rouge, LA. Two Artificial Intelligence (AI) models were developed to predict NOx concentrations before and after TiO2 application. Results showed that the NF model provided a better fitting to NOx measurements than the ANN model in the training, validation, and test steps. Results of a parametric study showed that traffic level, relative humidity, and solar radiation had the most effects on photocatalytic efficiency. In addition, the increase in wind speed and relative humidity negatively affected the effectiveness of NOx reduction efficiency. However, the increase in UV light intensity improved NOx removal efficiency of the surface coating.
  Authors: Asadi, Somayeh; Hassan, Marwa M.; Nadiri, Ataallah; Mohammad, Louay N.
  Authors: Asadi, Somayeh; Hassan, Marwa M.; Nadiri, Ataallah; Mohammad, Louay N.
  Year: 2013
  Document Type: Paper
  Subject: Environment; Materials; Pavements
  Session: 292
  Paper Number: 13-0918
• Measurement of Pavement Solar Reflectivity and Effect on Thermal Performance
  Abstract: Solar reflectivity (or albedo) plays an important role in the thermal behavior of pavements and other ground surfaces, and their resultant impacts on humans and the environment. This study developed a new albedo measurement system with a dual-pyranometer and automatic data acquisition system, and used it to conduct field measurements of solar reflectivity on different pavement materials and for long-term monitoring of albedo. The albedo values were obtained for commonly used land cover materials including asphalt, concrete and block paver surfacing materials with different designs, which can help reduce the uncertainty in understanding, evaluating and modeling the thermal behavior and environmental impacts of ground surfaces with different albedos. This study found that the albedo of pavement materials is high in the early morning and late afternoon; it is low and constant over time in the mid-day. This suggests that albedo should be measured near mid-day, which is addressed in one of two standard test procedures reviewed. Clouds will negatively influence the value of measured albedo. No significant seasonal variation in albedo was found over one year. No impact of wind speed or air temperature on albedo is observed with the instrument used. An empirical relationship between the cooling effect of increased albedo on a pavement’s high temperature and solar radiation was developed. The cooling effect has a positive correlation with the peak solar radiation intensity. This empirical relationship can be used to roughly estimate the cooling effect of increased albedo or heating effect of reduced albedo on pavement for various climates and seasons with different solar radiation intensities.
  Authors: Li, Hui; Harvey, John; Kendall, Alissa
  Authors: Li, Hui; Harvey, John; Kendall, Alissa
  Year: 2013
  Document Type: Paper
  Subject: Environment; Materials; Pavements
  Session: 292
  Paper Number: 13-1116
• Cooling Effect of Permeable Asphalt Pavement Under Both Dry and Wet Conditions
  Abstract: The improvement of the street thermal environment for walking and cycling is attracting increased attention as a strategy for increasing livability. This approach has also been proposed as a strategy for mitigating the local heat island effect and reducing energy use for buildings and vehicle air conditioning during hot periods. This research explored a potential pavement design and management strategy that potentially could be used for improving the street thermal environment and mitigating heat islands. Through field measurements on pavement test sections with both conventional and alternative designs, the thermal behavior and cooling effect of permeable asphalt pavements under both dry and wet condition were investigated. The overall 7-day average cooling effect of wetting once on permeable pavements for near-surface air is approximately 0.2 to 0.45°C; for the surface it is approximately 1.2 to 1.6°C; and approximately 1.5 to 3.4°C for the in-depth layers. Based on the findings, permeable asphalt pavements have the potential of being a type of cool pavements which produces lower temperatures and thus helps improve the thermal environment and mitigate the heat island effect. However, attention should be given to this type of pavements under dry conditions. As a pavement thermal management strategy, water from rain or irrigation systems might need to be applied to the pavements to produce a better cooling effect for improving the thermal environment and mitigating the heat island.
  Authors: Li, Hui; Harvey, John; Jones, David
  Authors: Li, Hui; Harvey, John; Jones, David
  Year: 2013
  Document Type: Paper
  Subject: Environment; Materials; Pavements
  Session: 292
  Paper Number: 13-1115
• Experimental Study of Sustainable Asphalt: Influence of Thermochromic Materials
  Abstract: Asphalt pavements are widely used in highways due to their good performance and relatively low construction and maintenance costs. However, the black color of asphalt implies that the sunlight is not reflected but absorbed, which raises the temperature of the asphalt pavement and impairs its long-term durability. Thermochromic materials are substances that can reversibly change their colors in response to temperature. They reflect solar energy at high temperature and absorb that at low temperature. The innovation by this paper is to investigate the use of thermochromic materials in asphalt to develop thermochromic asphalt, which will reduce the surface temperature of asphalt pavement and lead to improved durability. Their thermochromic transition temperatures, which were characterized by Differential Scanning Calorimetry (DSC), range from 19.83 to 34.8 °C. The latent heats are between 1.74 and 3.59 J/g. The heat capacities measured with modulated DSC at 15, 25 and 35 °C are in the range of 1.392-1.724 J/(g•°C). Thermal conductivities were calculated in the range of 0.1478-0.2282 W/(m•°C). Both heat capacities and thermal conductivities at 25 °C are higher than those at other temperatures due to phase transition. The red and black asphalt show relatively higher heat capacities and thermal conductivities than the conventional pure asphalt. Comparison measurements found that the surface temperature of thermochromic asphalt can be significantly lower than that of the conventional pure asphalt with maximum decrease as high as 6.6 °C during summer. During winter and nocturnal in summer, the surface temperature of thermochromic asphalts are higher than that of the conventional pure asphalt, which helps to keep asphalt pavement warm and alleviates the problem of icing. The reduced surface temperature during summer and increased surface temperature during winter using thermochormic materials can be both desirable. For use as roof, for example, the use of thermochromic asphalt can lead to energy saving for air conditioning as high as 24%. This not only reduces the energy cost but also helps mitigate urban heat island and improve air quality and comfort.
  Authors: Hu, Jianying; Yu, Xiong
  Authors: Hu, Jianying; Yu, Xiong
  Year: 2013
  Document Type: Paper
  Subject: Environment; Materials; Pavements
  Session: 292
  Paper Number: 13-2029
• Experimental Study on Nanometer TiO2 Doped with Fe3+ for Purification Effect of Automobile Exhaust in the Tunnel
  Abstract: This paper presents an experimental approach to study purification effect of automobile exhaust. Sol-gel method was used to prepare Fe3+ modified Titanium dioxide (TiO2). Purification tests were conducted in a self-developed instrument to study catalytic effects of TiO2 doped with different contents of Fe3+ through degradation rate. The modification mechanism was studied by X-ray diffraction (XRD) scanning. Results showed that doping iron ion had improved the light catalytic performance of nanometer through inhibiting the growth of TiO2 grain size. TiO2 doped with 0.1% iron ion showed the best catalytic effect. The degradation rates of CO and CO2, HC and NOX were 6.9%, 7.9%, 2.3% and 14.9% higher than the unmodified TiO2 under ultraviolet light conditions, respectively., 0.6%, 0.6%, 2.3% and 8.2% higher than the unmodified under incandescent light conditions, respectively.
  Authors: Jianzhong, Pei
  Authors: Jianzhong, Pei
  Year: 2013
  Document Type: Paper
  Subject: Environment; Materials; Pavements
  Session: 292
  Paper Number: 13-2563
• Durability Quantification for TiO2 Photocatalytic Concrete and Asphalt Pavements
  Authors: Hassan, Marwa
  Authors: Hassan, Marwa
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Environment; Materials; Pavements
  Session: 292
  Paper Number: 13-0901
• Using Artificial Intelligence Models to Evaluate Field Performance of Photocatalytic Asphalt Pavement for Ambient Air Purification
  Authors: Hassan, Marwa
  Authors: Hassan, Marwa
  Year: 2013
  Document Type: Presentation; Poster
  Subject: Environment; Materials; Pavements
  Session: 292
  Paper Number: 13-0918