Researchers in the US and Nigeria are studying the rheology of concrete to improve experimental mix design properties. To that end, the researchers have found ways to add the shells of cashews as a supplementary cementitious material without compromising concrete performance.
Researchers in the Civil Engineering Departments at Covenant University and Delta State University have presented modifications to the content of concrete, facilitating easier compliance and workability. This contributes to a more sustainable world for applications in the built environment.
The team’s results are expanded upon here, putting them into context in terms of concrete performance and the role that rheology plays in maintaining it.
A Compliant Material Turning Solid over Time
Concrete is a remarkable material. Composed of a mix of aggregates and paste, its ubiquity can be explained by the contrasting properties it exhibits from when it is freshly mixed as cement and water to when it hardens.
Initially malleable with plastic-like qualities via hydration, the paste gains strength, hardening into a robust mass, often of impenetrable material. It is a property known as “workability” and it is key in the successful exploitation of concrete. The property also allows it to be manipulated and conform to new shapes.
Contrary to almost all other things, concrete gets stronger as it gets older as a slow hydration rate continues years beyond the initial life cycle. The robustness in hardened concrete together with its compressive strength creates durability, fire, and impact resistance in addition to acoustic insulation properties that see its extensive adoption in the building industry. In tall constructions, high-performance concrete can significantly reduce the steel content of a column needed for reinforcement, making its use highly cost-efficient.