You are browsing the archives of 2009 February.

(corrected, courtesy of the comments from Dale Bentz, below)

The “verdict” is in - engineers at the National Institute of Standards and Technology say they have developed a technique that promises to double the service life of concrete. The soon-to-be patented method is the result of a project called VERDiCT - Viscosity Enhancers Reducing Diffusion in Concrete Technology. The technique entails mixing a nanoadditive into concrete to boost the viscosity of water molecules in its micropores. This, in turn, thickens the concrete solution at a microscopic level, slowing the diffusion of chloride and sulfate ions from road salt and other destructive agents into the concrete’s structure.

By delaying the entry of ions known to cause cracks and internal damage to concrete over time, NIST’s technique forestalls deterioration, says Project Manager Dale Bentz. According to Bentz, previous efforts to boost concrete’s lifespan have focused on increasing its density and making it less porous. While resulting products have proved stronger than conventional concrete, they’ve also demonstrated a propensity for cracking, he says. NIST’s approach is different, he contends, because its focus is microscopic viscosity. “Swimming through a pool of honey takes longer than making it through a pool of water,” he stresses. The key to NIST’s technique is the size of the additive’s molecules, he reports in a paper submitted to Concrete International magazine.

He says his team learned that - while additives with large molecules, such as cellulose ether and xanthum gum, can increase concrete’s viscosity - they aren’t effective at slowing ion diffusion. “When additive molecules are large but present in a low concentration, it is easy for the chloride ions to go around them, but when you have a higher concentration of smaller molecules increasing the solution viscosity, it is more effective in impeding diffusion of the ions,” he explains. Numerous experiments proved that additives with nanoscale molecules worked best at slowing ion diffusion. Another lesson learned was that, while additives could be mixed directly into concrete, better performance could be achieved by saturating sand and, then, mixing the sand into concrete.

Looking ahead, Bentz sees expense as a potential obstacle to commercialization. In an online Feb. 9, 2009,  Technology Review article, he reveals that additives totaled as much as 10 percent of the mixing water. his concrete’s composition. “The industry is comfortable with one percent, so there’s a cost factor, in that it’ll cost 10 percent more,” he admits. “Conventional admixtures are generally added at a concentration of 2 % of the mixing water or less. Thus, this additive could cost 5 times more than the cost of a conventional admixture and hence the desire to find better additives with equivalent activity at lower concentrations,” says Bentz Still, Bentz is optimistic. “We’ve demonstrated proof of concept, and now we’d like to find an additive that works at three or five percent concentration,” he says, noting that research is ongoing. Certainly the need for NIST’s technique exists. As the primary ingredient in millions of miles of roads and more than 600,000 bridges in the United States alone, concrete is an essential infrastructure component. Yet, according to a 2007 Federal Highway Administration report, more than 25 percent of U.S. bridges are rated as “structurally deficient” or “functionally obsolete.” In a separate infrastructure report issued this year, the American Society of Civil Engineers, gave U.S. bridges a “C” and roads a shameful grade of “D-.”

Back in August, we noted the work Daniel Nocera a professor of chemistry at MIT, who is leading has developed an unprecedented electrolysis process that uses the sun’s energy to split water molecules into oxygen and hydrogen gases. The gases can then be stored and later run through a fuel cell to produce electricity as needed. We noted then:

The key to the process is a newly developed catalyst that produces oxygen gas from water. Inexpensive and easy to make, the catalyst consists of cobalt metal, phosphate and an anode, placed in water. When electricity – from a photovoltaic cell or any electrical source – is run through the catalyst, the cobalt and phosphate form a thin film on the electrode’s surface, creating oxygen gas.

Also back then, Science magazine noted, after talking with Nocera, that the qualitative leap would come when the process was independent of water quality:

A final big push will be to see if the catalyst or others like it can operate in seawater. If so, future societies could use sunlight to generate hydrogen from seawater and then pipe it to large banks of fuel cells on shore that could convert it into electricity and fresh water, thereby using the sun and oceans to fill two of the world’s greatest needs.

Apparently, like us, a lot of people are tracking Nocera’s progress. In front of what was reported to be a “packed house” at the AAAS confab, Nocera told the audience that his system now works with both sea water and “dirty” water, and that the catalyst his group is working with is relatively self-healing. An article explaining the details of these developments is supposed to be published in a week or two. Stay tuned.

The American Ceramic Society has now posted videos of four lectures presented last October as part of the Society’s annual meeting. Each of the lectures is approximately one-hour in length and presented in a “YouTube” level of quality to provide the most ease in viewing.

Each of the lectures is presented by a luminary in a particular field of ceramics who have already been recognized for their outstanding contributions to science, technology, engineering and society.

“Hunting the Perovskite Range,” Harlan U. Anderson (Arthur L. Friedberg Memorial Lecture) Anderson is a Curators’ Professor of ceramic of engineering at Missouri University of Science and Technology in Rolla, Mo. His teaching, research interests and long term involvement in both insulating and conducting oxides have lead to him being recognized as one of the world’s leading authorities on electronic ceramics, solid oxide fuel cells and oxygen separation membranes.

“Sol-gel processing: A retrospective and perspective, ” C. Jeffrey Brinker (Edward Orton Jr. Memorial Lecture) Brinker is jointly employed at the Sandia National Laboratories and the University of New Mexico. He has been recognized nationally and internationally for his pioneering work in sol-gel processing – the formation of ceramic materials from molecular precursors. This early work launched the successful series of MRS symposia entitled “Better Ceramics Through Chemistry” and culminated in the publication of Sol-Gel Science (1990) with coauthor George Scherer (see below). Through the creative use of silane coupling chemistry, he devised a simple, inexpensive means to prepare aerogels, the world’s lightest solids, at room temperature and pressure.

“Understanding Frost Damage ,” George W. Scherer (Della Roy Lecture, on behalf of the Cements Division) Scherer is a professor in the Department of Civil & Environmental Engineering at Princeton University, and a member of the Princeton Materials Institute. His research involves mechanisms of deterioration of concrete and stone, particularly by crystallization of ice and salts in the pores.

“Interfacial kinetic engineering: How far have we come since Kingery’s inaugural Sosman address?” Martin P. Harmer (Robert B. Sosman Award and Lecture on behalf of the Basic Science Division) Harmer is the Alcoa Professor of materials science and engineering and the director of the Center for Advanced Materials and Nanotechnology at Lehigh University, Bethlehem, Pa. His research has focused on the control of interfacial transport processes and microstructure in structural and electronic ceramics

Everyone who has paid their dues in a chem lab is familiar with processes that precipitate materials shaped as spheres, cubes, rods and needles. It’s also not unusual to see rhombohedra, whiskers, tubes, flowers and rosette particles of inorganic/organic materials in the micron-scale. But, how about a pill-shaped particle? You know - round, with slightly out-curving sides. Never seen that kind of precipitate? No, neither have I, until now. Apparently, the synthesis of monodisperse, biconvex pill-shaped microparticles, precipitated directly from an aqueous solution, has not yet been reported for any natural or man-made materials. But, ACerS member and Yeditepe University (Istanbul, Turkey) professor A. Cuneyt Tas reports he has synthesized biconvex micropills of CaCO3 (of the vaterite form). Tas says he first cools (at 4°C) aqueous solutions of CaCl2-gelatin-urea and then heats the same at 70°C for 24 hours. He says this yields a products “looking like those cute aspirin tablets everybody know, but synthesized for the first time in water-based solutions at the micron-scale.” (It should be noted that aspirin tablets and the like are produced by a compressing powders into a die formed for the desired pill shape.) CaCO3 powders are widely used in pharmaceutical, cosmetics, toothpaste, rubber, plastic, papermaking, printing ink, food and biomedical industries. An article about Tas’ work appears in the current issue of the International Journal of Applied Ceramic Technology.

SCHOTT, one of the world’s largest and most innovative glassmakers, reports the accomplishment of another first - the combination of solar panels and colored glass in the design of a stunningly beautiful stairway facade, integrated into the walls of the firm’s administration building in Mainz, Germany. Designed by German artist Paul Wurdel, the beautiful solar stairway combines 140 of the firm’s “Artista” fused-color glass panels with 195 irregularly-arranged “Asi Thru” photovoltaic modules from SCHOTT Solar in Putzbrunn, Germany. The 24-meter high “solar façade,” performs three functions. It generates power, lowers energy costs and - thanks to its clear and vibrant colors - also serves as an attractive “business card for the firm,” says Udo Ehlers, head of SCHOTT’s architectural glass sales. “It’s really turned what used to be a rather somber staircase into a colorful world of adventure,” he comments. “You get a rainbow of watercolor images in various shades, and it becomes even more dynamic, when observers move around.” SCHOTT’s plant in Grünenplan, Germany, processed the glass design, and the combination of “fusing glass and solar modules for the first time ever posed a unique challenge for all those involved in the project,” according to Hartmut Glenewinkel, the project’s design consultant and manufacturing director. Glaswerke Arnold, based in Merkendorf, Germany, was given the challenging job of fabricating the triple-layer insulated laminate panel. The outside layer of the module consists of partially tempered glass panes, backed by randomly placed, laminated solar modules.