Researchers Develop Method of Directly Observing Setting of Concrete Paste
Researchers have developed a nondestructive and noninvasive optical technique that can determine the setting times for various types of cement paste, which is used to bind new and old concrete surfaces. The new method could aid in the development of optimized types of cement with less impact on the environment.

"Our noninvasive optical method characterizes and determines the setting time of cement, which is a very important parameter for the construction industry," said José Ortiz-Lozano, a member of the research team from Universidad Autónoma de Aguascalientes, Tecnológico Nacional de México and Centro de Investigaciones en Óptica, in Mexico. "It can also precisely assess the cement hydration process in real-time. This information is crucial for both the study of physical chemistry and the quantitative characterization of the nanomechanical properties of cement-based materials."

In the Optical Society’s (OSA) journal Applied Optics, the researchers describe the new method, which combines laser-based technology with an optical model to calculate the dynamic behavior of the cement paste. The researchers show that their approach can accurately calculate both the initial setting time — the time available for mixing the cement and placing it in position — and the final setting time, when the cement reaches its full strength.

"Our group is trying to enhance the performance of cement-based materials, such as cement pastes, mortars and concrete," said Ortiz-Lozano. "New material characterization methods, such as the one we report here, can be used to improve the behavior and performance of cement by optimizing its constituents. This could lead to new types of cement that use less water and raw materials like limestone and clay, which would make them more environmentally friendly."

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