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Ying Wang

University of Miami, PhD
EREF Scholar 2021

Modification on Fly Ash Specifications to Allow the Reuse of Marginal and Unconventional Source Fly AshesProject Description:
Coal combustion products (CCP) are the materials produced when coal is burned to generate electricity. These include fly ash, bottom ash, boiler slag, flue gas desulfurization gypsum, etc. Fly ash is a fine, powdery substance that “flies up” from the coal combustion chamber and is captured by emissions controls. Fly ash is the most commonly used supplementary cementitious material (SCM) in concrete. The addition of fly ash makes the fresh concrete easier to mix, and makes the hardened concrete more resistant to erosion. It can also reduce the CO2 emissions which are mainly associated with production of cement clinker. Therefore, availability of fly ash is essential for the continued production of sustainable and durable concrete.

The decreasing amount of high-quality virgin fly ash cannot meet the demand of the concrete industry. One possible solution is to recover historically landfilled or ponded fly ashes. Fly ash was landfilled in the past decades due to supply exceeding demand, material being lower-quality/off-spec, among other reasons. With over 1.3 billion tons of landfilled and ponded fly ash in the US, the fly ash shortfalls in the concrete industry can potentially be alleviated.

Ying’s research focuses on the reactivity and beneficial reuse of marginal (barely passing the current requirements) and unconventional source (reclaimed, processed and off-spec) fly ashes, and other solid waste materials (such as metal slags and bottom ash) to significantly reduce industrial waste in landfills. For example, one use for fly ash is to partially replace cement in concrete, leading to more sustainable and durable construction materials. By monitoring the reactivity and long-term performance of such materials, the feasibility of using unconventional fly ash, and other industrial by-products to replace cement in concrete can be determined. Once the material is proved feasible to use, the corresponding standards should be proposed or updated. A major aim of Ying’s PhD research is the modification of current US fly ash specifications to allow for the use of alternative fly ashes, which are currently landfilled, ponded, and stockpiled.

Ying is a PhD student in Civil Engineering at the University of Miami since January 2020. She was also a visiting scholar there from May 2018 to June 2019. She obtained her M.S. and B.S. at the University of Science and Technology Beijing. Her undergraduate and master’s research focused on industrial solid waste utilization and novel infrastructure materials, such as processing and resource utilization of mine tailings to create green building materials. Her ultimate career goal is to become a Professor working on solid waste and supplementary cementitious materials including various types of solid wastes (fly ash, bottom ash, municipal waste incineration fly ash, steel slag, etc.). She hopes to make a long-term contribution in this field to substantially increase the beneficial reuse of such unconventional solid wastes.