Paving the way to more sustainable cement products
Paving the way to more sustainable cement products lead image
After water, cement is considered the most consumed commodity. Over 4 billion tons are poured annually. Despite this ubiquity, the rheological response of cement paste is not fully understood.
Ioannou and Stephanou present a study on the rheological response of cement paste — the simplest form of cementitious fluids, in which water is added to cement powder.
“Controlling the rheological behavior of cement pastes, mortars, and concrete is paramount for long-term performance and durability,” said author Pavlos Stephanou. “After realizing that there was no rheological model for cement paste that was thermodynamically admissible and self-consistent, I decided that my team and I should get involved.”
Cement fluids gradually solidify as a result of chemical reactions between cement particles and water, forming a layer of calcium silicate hydrates. Because of this, any rheological description requires the use of non-equilibrium thermodynamics. Using the generalized bracket formalism, the researchers developed a continuum model that is consistent with thermodynamic laws as extended to beyond equilibrium states.
The model was reasonably consistent with experimental data, particularly on large time scales, showing its reliability.
The researchers plan to continue improving the model by accounting for variability in water content and amount of sand or gravel, as well as the exothermic hydrolysis reactions that change the temperature of the cement as it sets. Eventually, they hope to use the model in computational fluid dynamics simulations to help develop new, optimized cementitious materials that can serve specific construction needs.
“The optimization of cement is paramount as it is directly related to the sustainability of cities, construction, and infrastructure,” Stephanou said.
Source: “Nonequilibrium thermodynamics modelling of the rheological response of cement pastes,” by Amalia K. Ioannou and Pavlos S. Stephanou, Journal of Rheology (2023). The article can be accessed at https://doi.org/10.1122/8.0000643 .
