It’s been quite a week for cement stories in Cosmos. First, we reported on attempts to create a living concrete by combining sand and bacteria.
Now, we are pleased to present this real-time characterisation of cement setting, courtesy of a team of Mexican researchers from Universidad Autónoma de Aguascalientes, Tecnológico Nacional de México and Centro de Investigaciones en Óptica.
For good reason. They have developed a non-destructive and non-invasive optical technique that can determine the setting times for various types of cement paste, which is used to bind new and old concrete surfaces.
And this, they say in a paper in the journal Applied Optics, could aid in the development of optimised types of cement with less impact on the environment.
The new method uses the optical properties of cement paste to directly calculate the initial and final cement setting time by measuring the diffuse light that reflects off the cement.
As the cement sets, the diffuse light reflection changes as it reacts with water and the spaces between the cement particles change. The amount of water present and the protective surface layer at each setting stage also influence the diffuse reflection properties.
The researchers combined the diffuse reflection measurements with the Kubelka-Munk model, which is used to describe diffuse reflection of opaque samples.
“This new optical method was developed using tools, components and materials common among the optical industry,” says co-author José Ortiz-Lozano.
“It would be, therefore, quite simple and economic to implement in cement quality control laboratories. It can be applied to any type of cement once the appropriate calibration is performed with the Kubelka-Munk model.”