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In recent years, an increase of environmental temperature in urban areas has raised many concerns. These areas are subjected to higher temperature compared to the rural surrounding areas. Modification of land surface and the use of materials such as concrete and/or asphalt are the main factors influencing the surface energy

In recent years, an increase of environmental temperature in urban areas has raised many concerns. These areas are subjected to higher temperature compared to the rural surrounding areas. Modification of land surface and the use of materials such as concrete and/or asphalt are the main factors influencing the surface energy balance and therefore the environmental temperature in the urban areas. Engineered materials have relatively higher solar energy absorption and tend to trap a relatively higher incoming solar radiation. They also possess a higher heat storage capacity that allows them to retain heat during the day and then slowly release it back into the atmosphere as the sun goes down. This phenomenon is known as the Urban Heat Island (UHI) effect and causes an increase in the urban air temperature. Many researchers believe that albedo is the key pavement affecting the urban heat island. However, this research has shown that the problem is more complex and that solar reflectivity may not be the only important factor to evaluate the ability of a pavement to mitigate UHI. The main objective of this study was to analyze and research the influence of pavement materials on the near surface air temperature. In order to accomplish this effort, test sections consisting of Hot Mix Asphalt (HMA), Porous Hot Mix asphalt (PHMA), Portland Cement Concrete (PCC), Pervious Portland Cement Concrete (PPCC), artificial turf, and landscape gravels were constructed in the Phoenix, Arizona area. Air temperature, albedo, wind speed, solar radiation, and wind direction were recorded, analyzed and compared above each pavement material type. The results showed that there was no significant difference in the air temperature at 3-feet and above, regardless of the type of the pavement. Near surface pavement temperatures were also measured and modeled. The results indicated that for the UHI analysis, it is important to consider the interaction between pavement structure, material properties, and environmental factors. Overall, this study demonstrated the complexity of evaluating pavement structures for UHI mitigation; it provided great insight on the effects of material types and properties on surface temperatures and near surface air temperature.

ContributorsPourshams-Manzouri, Tina (Author) / Kaloush, Kamil (Thesis advisor) / Wang, Zhihua (Thesis advisor) / Zapata, Claudia E. (Committee member) / Mamlouk, Michael (Committee member) / Arizona State University (Publisher)
Created2013
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Enzyme-induced carbonate precipitation (EICP) is an emerging technology for ground improvement that cements soil with calcium carbonate to increase strength and stiffness. EICP-improved soil can be used to support new facilities or it can be injected under existing facilities to prevent excessive deformation. The limitations for commercial adoption of EICP

Enzyme-induced carbonate precipitation (EICP) is an emerging technology for ground improvement that cements soil with calcium carbonate to increase strength and stiffness. EICP-improved soil can be used to support new facilities or it can be injected under existing facilities to prevent excessive deformation. The limitations for commercial adoption of EICP are the cost and the lack of implementation at field-scale. This research demonstrated two ways to reduce the cost of EICP treatment at field-scale. The first was a modification to the EICP solution such that lower amounts of chemicals are needed to achieve target strengths. The second was to use a simple and inexpensive enzyme extraction method to produce the enzyme at a large-scale. This research also involved a two-stage scale-up process to create EICP biocemented soil columns using a permeation grouting technique. The first stage was at mid-scale where 0.6 m x 0.3 m-diameter EICP biocemented soil columns were created in boxes. This work confirmed that conventional permeation grouting equipment and methods are feasible for EICP soil treatment because the columns were found to have a uniform shape, the injection method was able to deliver the EICP solution to the edges of the treatment zone, and downhole geophysics was effectively used to measure the shear wave velocity of the biocemented soil mass. The field-scale stage was performed in the Test Pit facility at the Center for Bio-mediated and Bio-inspired Geotechnics' Soils Field Laboratory. Seven biocemented soil columns were created with diameters ranging from 0.3-1 m and heights ranging from 1-2.4 m. Effective implementation at this scale was confirmed through monitoring the injection process with embedded moisture sensors, evaluating the in situ strength improvement with downhole geophysics and load testing, and testing of the excavated columns to measure shear wave velocity, dimensions, carbonate content, and strength. Lastly, a hotspot life cycle assessment was performed which identified ways to reduce the environmental impacts of EICP by using alternative sourcing of inputs and extraction of byproducts. Overall, this research project demonstrates that EICP is a viable ground improvement technique by way of successfully producing field-scale biocemented soil columns.
ContributorsMartin, Kimberly Kathryn (Author) / Kavazanjian, Jr., Edward (Thesis advisor) / Zapata, Claudia E. (Committee member) / van Paassen, Leon (Committee member) / Arizona State University (Publisher)
Created2021