Shiho Kawashima | Cementing the Path to Solid Construction
Assistant Professor of Civil Engineering and Engineering Mechanics
—Photo by Eileen Barroso
When you drive along a concrete boulevard, cruise over a smooth overpass, or gaze up at a giant skyscraper, you might marvel at its construction, never thinking that how the actual cement was mixed with water might affect the overall lifespan of that particular structure or road.
“Typically, when people think of concrete, they think of the hardened road, the building, or the bridge,” says Shiho Kawashima, assistant professor of civil engineering and engineering mechanics and an alumna of the Engineering School. “I’m interested in what happens immediately after you mix cement with water and what flow properties exist.”
Kawashima’s experimental research focuses on cementitious materials at the nanoscale. She investigates the rheology (basic flow properties) of cement-based materials, which she says is “incredibly complex because hydration—the reaction between cement and water—is constantly progressing pretty much the entire lifetime of the material, beginning at its liquid state.”
Of particular interest to Kawashima is oil well cementing. She hopes to design highly adaptive slurries that can exhibit high initial flowability to facilitate pumping, but then once pumping stops, they can immediately exhibit rapid gelation. This is key, she explains, because this high gel strength can actually resist gas penetration from surrounding geological formations and potentially eliminate problematic environmental scenarios, such as gas leaks from the oil wells.
Kawashima points to the 2010 BP oil well disaster in the Gulf of Mexico as an example of an insufficient cementing operation that caused a massive, accidental marine oil spill. To avoid such calamities and prevent gas penetration, she says, it’s crucial to control the rheology as the cement slurry transitions from a water-like fluid to a rock-like solid.
Part of her research interests in this area focuses on examining the influence of different mineral and chemical additives to enhance select properties, including thixotropy. Thixotropy refers to the property exhibited by certain gels of becoming fluid when stirred or shaken and returning to its semisolid state when still.
“Cementing is a very critical process, but it’s very difficult to achieve successfully. If you can design a highly thixotropic cement slurry with the use of innovative additives, this would be a highly effective approach to the environmental problem,” Kawashima notes.
While concrete is, by no means, a novel material, engineers have just recently been able to dig deeper in their research. “With the development and availability of equipment … we have the tools now to characterize structure at the nanoscale,” adds Kawashima. “This is particularly important with cementitious materials because they are heterogeneous at all scales. We’re only now starting to really obtain fundamentals even though the material has been used for centuries.”
Kawashima’s research is mostly limited to the lab, but, she stresses, working with industry is key to making a huge impact.
Kawashima joined the Columbia Engineering faculty in January 2013 after earning her BS in civil engineering at the School and completing both her master’s and PhD in civil and environmental engineering at Northwestern University.
BS, Columbia Engineering, 2007; MS, Northwestern University, 2009; PhD, Northwestern University, 2012
-by Janet Haney