Browsing by Author "Zhang, Yating"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Assessment and Life-Cycle Analysis of Recycled Materials for Sustainable Highway(2016) Zhang, Yating; Goulias, Dimitrios G; Aydilek, Ahmet H; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Recycled materials replacing part of virgin materials in highway applications has shown great benefits to the society and environment. Beneficial use of recycled materials can save landfill places, sparse natural resources, and energy consumed in milling and hauling virgin materials. Low price of recycled materials is favorable to cost-saving in pavement projects. Considering the availability of recycled materials in the State of Maryland (MD), four abundant recycled materials, recycled concrete aggregate (RCA), recycled asphalt pavement (RAP), foundry sand (FS), and dredged materials (DM), were studied. A survey was conducted to collect the information of current usage of the four recycled materials in States’ Department of Transportation (DOTs). Based on literature review, mechanical and environmental properties, recommendations, and suggested test standards were investigated separately for the four recycled materials in different applications. Constrains in using these materials were further studied in order to provide recommendations for the development of related MD specifications. To measure social and environmental benefits from using recycled materials, life-cycle assessment was carried out with life-cycle analysis (LCA) program, PaLATE, and green highway rating system, BEST-in-Highway. The survey results indicated the wide use of RAP and RCA in hot mix asphalt (HMA) and graded aggregate base (GAB) respectively, while FS and DM are less used in field. Environmental concerns are less, but the possibly low quality and some adverse mechanical characteristics may hinder the widely use of these recycled materials. Technical documents and current specifications provided by State DOTs are good references to the usage of these materials in MD. Literature review showed consistent results with the survey. Studies from experimental research or site tests showed satisfactory performance of these materials in highway applications, when the substitution rate, gradation, temperature, moisture, or usage of additives, etc. meet some requirements. The results from LCA revealed significant cost savings in using recycled materials. Energy and water consumption, gas emission, and hazardous waste generation generally showed reductions to some degree. Use of new recycled technologies will contribute to more sustainable highways.Item Urban Heat Projections and Adaptations in a Changing Climate, Washington D.C. as a Case Study(2019) Zhang, Yating; Ayyub, Bilal M; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Carbon emission from human activities has changed the Earth’s overall climate and intensified extreme weather and climate events. Climate risks are regionally uneven due to different vulnerability levels of populations, infrastructures, and natural resources. Assessing local-scale risk is important in supporting climate preparation, adaptation planning, and policy development for cities to overcome climate change. This dissertation developed the Asynchronous Regional Regression Model (ARRM) that statistically downscales data of Coupled Model Intercomparison Project Phase Five (CIMP5) into locations of observing stations, employed the Weather Research and Forecasting (WRF) model that dynamically downscales data of Community Earth System Model version one (CESM1) into fine-grid results, and proposed a framework to assess adaptation strategies for vulnerable infrastructure systems incorporating the probabilistic risk approach. Based on those models and methods, this dissertation projected the trend and level of the urban heat island (UHI) effect and heat waves in the rest of the 21st century for Washington D.C. and its surrounding areas, evaluated mitigation options for heat waves, and assessed adaptation strategies for electrical power systems in such area. Projections based on the higher greenhouse gas (GHG) concentration scenario, Representative Concentration Pathway (RCP) 8.5, indicate a growing trend of heat waves at Washington D.C. in the rest of the century. The amplitude of heat waves may grow by 5.7°C, and frequency and duration may increase by more than twofold by the end of the century. The UHI effect may increase in summer and decrease in winter. The lower scenario, RCP 2.6, leads to slight decay of heat waves after a half-century of increase, and a minor change in the UHI effect. Five heat wave mitigation strategies based on cool roofs, green roofs, and reflective pavements were evaluated in three future time periods. Results indicated that applying cool roofs and green roofs in the city scale can effectively reduce heat wave amplitude and duration, whereas the effectiveness of reflective pavements is negligible. However, reflective pavements can be more cost-effective than green roofs because of their low initial and maintenance costs. Electrical power systems are particularly vulnerable to extreme heat. Results indicated that power outage risk caused by temperature rise may increase seventyfold in the Washington metro area by the end of the century. If summer peak load on the electrical grid is cut by three quarters, there would be a twentyfold increase instead. This reduction is achievable by installing solar panels on building roofs, which can add an average generation capacity of 13.02 GW to the existing power system. Increasing the use of rooftop photovoltaics (PV) can increase the level of benefits.