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Credit: Duke U. A new model of the energy landscape of glass shows that it contains fractal basins (far right) that are rougher than previously thought. According to the press release, “The new description makes sense of several behaviors seen in glasses, like the property known as avalanching, which describes a random rearrangement of molecules that leads to crystallization.” The paper is “Fractal free energy landscapes in structural glasses” (DOI: 10.1038/ncomms4725). n Concrete abstracts describe improved concrete formulations Researchers at the University of Wisconsin-Milwaukee have developed a durable, water-resistant, and malleable concrete formulation—called Superhydrophobic Engineered Cementitious Composite (SECC)—that they estimate could last more than 120 years. They engineered the composite to resist cracking using two superior characteristics. First, they made the concrete superhydrophobic. “Additives in the hybrid change the concrete on a molecular level when the pavement hardens, creating a spiky surface that, although microscopic, causes the water to bead and roll off,” states the university press release. Second, the SECC gains some flexibility by mixing thin unwoven poly(vinyl alcohol) fibers into the concrete, which help prevent crack growth. By allowing small cracks to form, but not grow, the fibers help distribute stress loads through small spaces that water cannot penetrate. “Our architecture allows the material to withstand four times the compression with 200 times the ductility of traditional concrete,” says civil engineering and mechanics professor Konstantin Sobolev in the press release. Although SECC is more expensive than standard concrete, the extended lifetime saves repair and replacement costs. The scientists speculate it will be most practical in applications that undergo continuous loading, such as bridge approach decks. Another group of researchers from the Institute of Science and Concrete Technology at the Polytechnic University of Valencia (Spain), Jaume I University of Castellón (Spain), Imperial College London (United Kingdom), and São Paulo State University (Brazil) has been using ceramic wastes—namely, brick— to produce more environmentally friendly and waste-reducing concrete. Using only ceramic residue, chemical activator, and water, the group produced a strong portland cement alternative. It has experimented with red brick clay, mixing it with sodium hydroxide or with sodium silicate and sodium hydroxide. The team published those results in Construction and Building Materials last year. The paper is “Properties and microstructure of alkali-activated red clay brick waste” (DOI: 10.1016/j.conbuildmat. 2013.01.031). “The process to make cement in this case is very simple. First, grind the brick and mix with the activating solution. Immediately after kneading it together with the barren, the cement is ready to be placed in molds and subjected to a special hardening process at high temperature,” says author María Victoria Borrachero in a press release. The team is now experimenting with ceramic wastes, particularly bathroom ceramic or porcelain tile, and is working on replacing the activator with more sustainable replacements, too. “We have already done tests with rice husk ash, and the results are very positive. Its use would yield an even more sustainable and cheaper final product, because it would be composed almost entirely of reused waste,” says Borrachero. n Credit: U. of Wisconsin–Milwaukee Students at the University of Wisconsin-Milwaukee install a test slab of their Superhydrophobic Engineered Cementitious Composite. American Ceramic Society Bulletin, Vol. 93, No. 5 | www.ceramics.org 15


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