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posted by mrpg on Tuesday June 08, @09:43AM   Printer-friendly
from the cement-cements-cembalos dept.

Visualizing cement hydration on a molecular level:

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.

Journal Reference:
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)


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  • (Score: 1) by khallow on Tuesday June 08, @04:25PM

    by khallow (3766) Subscriber Badge on Tuesday June 08, @04:25PM (#1143184) Journal

    Have a look and total up the six categories: transportation 29%, electricity production 25%, industry 23%, commercia/residential 13%, agriculture 10% and land use/forestry 12%.

    From the link:

    Land Use, Land-Use Change, and Forestry in the United States is a net sink and removes approximately 12 percent of these greenhouse gas emissions, this net sink is not shown in the above diagram.

    So if you add the first five categories, they total 100% (up to round off error) as one would expect. If we were to include the land use/forestry category, then the first five would actually total roughly 114% with 12% of that 114% taken off by land use to get 100%.

    Moral of this post: if you're going to complain about funny math, make sure your math isn't funnier.