from the cement-cements-cembalos dept.
The concrete world that surrounds us owes its shape and durability to chemical reactions that start when ordinary Portland cement is mixed with water. Now, MIT scientists have demonstrated a way to watch these reactions under real-world conditions, an advance that may help researchers find ways to make concrete more sustainable.
[...] Cement in concrete contributes about 8 percent of the world's total carbon dioxide emissions, rivaling the emissions produced by most individual countries. With a better understanding of cement chemistry, scientists could potentially "alter production or change ingredients so that concrete has less of an impact on emissions, or add ingredients that are capable of actively absorbing carbon dioxide," says Admir Masic, associate professor of civil and environmental engineering.
[...] Using Raman microspectroscopy, the MIT scientists observed a sample of ordinary Portland cement placed underwater without disturbing it or artificially stopping the hydration process, mimicking the real-world conditions of concrete use. In general, one of the hydration products, called portlandite, starts as a disordered phase, percolates throughout the material, and then crystallizes, the research team concluded.
Hyun-Chae Loh, Hee-Jeong Kim, Franz-Josef Ulm, et al. Time-Space-Resolved Chemical Deconvolution of Cementitious Colloidal Systems Using Raman Spectroscopy, Langmuir (DOI: 10.1021/acs.langmuir.1c00609)