Cement Mixture Sprouts Self-Organized Structures
While working to incorporate fly-ash into its cement so as to lower its carbon footprint, CTS Cement Manufacturing Corp., Cypress, Calif., a manufacturer of specialty fast-setting hydraulic cement and shrinkage compensating cement, made an interesting discovery related to structures found in the ensuing cement mixture.
Found in mixtures of coal fly ash and hydrated calcium sulfoaluminate cement, these intriguing structures consist of micron-sized glass spheres upon which needles have grown radially. While these needles actually usually grow randomly in cement, in fly ash and cement mixtures they organize themselves as spines on the round fly ash particles.
According to Dr. Eric Bescher, vice president, cement technology, CTS Cement, this is the first time these complex structures have been seen. The structures are very small, typically a few tens of microns in size, and are only seen clearly under an electron microscope.
“We are excited about discovering these new self-organized inorganic architectures,” Bescher says. “Think of these structures as micron-sized sea urchins shells embedded in cement paste. We have some indication they may play a beneficial role in reinforcement of concrete or in shrinkage mediation. Our work is in progress and we are investigating the influence they could have on other properties of construction materials.”
Besides his work with CTS Cement, Bescher is author of more than 40 research articles and several patents. He is associate adjunct professor at the University of California Los Angeles, where he teaches undergraduate and graduate courses in Materials Science, and a distinguished professor at the Zhengjiang University, Hangzhou China. His work focuses on the fundamentals of advanced cementitious materials.
CTS Cement says it is not aware of reports on similar structures in scientific literature to date. It is possible these structures grow and develop only in calcium sulfoaluminate/fly ash mixtures.
Bescher explains that the discovery is the result of attempts to make the already green Rapid Set even greener. “By substituting some of the Rapid Set cement with fly ash, we will further reduce the already minimal carbon footprint of the cement while finding a use for a waste material,” Bescher says. “In this process, we stumbled onto something unexpected and exciting, the significance of which is to be determined.”
CTS Cement is in the process of further investigations on the so-called self-organized BescherBalls to understand their significance and the role they can play in construction materials. BescherBalls is the working name for these innovative structures. “We have much more to learn about the ingenious design and the formation mechanism of these structures,” Bescher says. “Our research teams are hard at work.”
Jerry Hoyle, CTS president, notes that this discovery will likely offer the design and construction industry a new alternative for specifying concrete as a green solution. “We’re excited that our commitment to research and development efforts has provided new opportunities for our marketplace.”