The Expanded Shale, Clay and Slate Institute (ESCSI) recognized Yuqiu Ye and Francisco Javier Zapata as the recipients of the 2021-22 John Ries Scholarship. In its third year, the annual scholarship program celebrates the legacy of retired ESCSI Technical Director John Ries by honoring exceptional civil engineering students.
While traditionally ESCSI only honors one scholarship recipient per academic year, the caliber of qualified applications led the institute to award a $5,000 scholarship to two students. Their passion for research in expanded shale, clay and slate (ESCS) materials and excellent academic track records made deciding between the two an impossible choice.
Already a published author of four scholarly articles, Ye’s extensive research on lightweight fill for geotechnical applications caught the attention of ESCSI. In April 2022, the civil engineering student was presented with his award and a ceremonial check on the University of Kansas’ campus with representatives from ESCSI member company, Buildex, in attendance.
Backed by the John Ries Scholarship, Ye is now in the position to study the performance benefits of lightweight aggregate as a load transfer platform (LTP) material in column-supported embankments. In application, column-supported embankments have been increasingly used for major highways, railways and storage facilities built on soft soil. The embankment consists of a LTP above columns, which may be unreinforced or reinforced by geosynthetics. While aggregate made of sand or crushed stone is commonly used as a LTP material, it is very heavy and may induce excessive subsoil settlement. This can affect the long-term performance of column-supported embankments and ultimately, compromise the structural integrity of the above-ground road or structure.
Ye believes that lightweight aggregate is a smarter backfill material for LTPs. Its ultra-lightweight nature will effectively reduce vertical stresses on geosynthetics and subsoils, and it can provide better soil arching due to its high friction angle. However, no study has been conducted to prove this claim — until now. Ye and his research team at the University of Kansas will carry out two physical model tests using regular river sand and lightweight aggregate in the LTP. Through this extensive study, Ye hopes to illustrate the advantages of using lightweight aggregate over regular aggregate in column-supported embankments.
Passionate about leveraging his research to advance the field of civil engineering, this study funded by the John Ries Scholarship is just a springboard for Ye. Once he receives his doctorate from the University of Kansas, he would like to continue his research in a university faculty position. Ye is also entertaining the idea of joining a consulting firm as an engineer to promote the use of lightweight aggregates for geotechnical applications.
Zapata has been described by his advisors at North Carolina State University as a true innovator, much like the vocabulary many have used to describe John Ries. A dedicated student, Zapata stood out among the number of qualified scholarship applicants for his trailblazing research on the disposal of cemented liquid radioactive wastes. Impressed by his research and its potential to help address a pressing societal and environmental issue, representatives from ESCSI member company, Stalite, presented the award to Zapata in April 2022 on behalf of ESCSI.
With the scholarship money from ESCSI, Zapata is now in the position to conduct extensive research using lightweight aggregates as a means of encapsulating and disposing of spent nuclear wastes in a more efficient, sustainable manner. Zapata’s research is timely, as every year the United States produces large amounts of high-level liquid nuclear waste as a result of maintaining the country’s nuclear weapons stockpile and the recycling of spent nuclear fuel. Currently, the cementation of liquid radioactive wastes depends on the chemical binding of the liquid waste. Cement based binders have limitations because liquid wastes can have any level of pH, salt and organics (among other elements) that may affect the hardening of the cement. This would ultimately result in an unpredictable strength and durability of the final product.
To address this problem, Zapata proposes the use of fine lightweight aggregates that are essentially ceramic particles. This lightweight aggregate material has a pore size distribution of less than 0.001 mm in diameter, resulting in large capillary forces that will retain the waste liquid. Lightweight aggregates are produced with up to 35 percent porosity. Calculations show that approximately 300 to 360 kg of liquid waste can be stored in 1.0 m3 of cemented waste without compromising the product’s strength and durability capabilities.
Through his research, Zapata aims to demonstrate how lightweight aggregates can serve as an attractive solution for the disposal of cemented liquid radioactive wastes. In application, it can help extend the service life of concrete structures while addressing significant societal and environmental issues.
Zapata will graduate from North Carolina State University in May 2023 with a Master of Science in Civil Engineering with a focus on Cementitious Materials. The sky will surely be the limit for this year’s John Ries Scholarship recipient.
Ye and Zapata’s demonstrated excellence in research and academics is nothing short of an inspiration for ESCSI’s members. The association is looking forward to watching both recipients lead successful careers and serve as compelling advocates for the use of lightweight aggregates to help address societal, structural and environmental challenges.
To learn more about ESCSI or the John Ries Scholarship, please visit https://www.escsi.org/.