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At the recently concluded Advances in Cement-based Materials meeting organized by ACerS’ Cements Division and ACBM, Karen Scrivener of the Ecole Polytechnique Fédérale de Lausanne (Switzerland) was selected by the organizers to deliver the Della Roy Lecture. Scrivener is a highly respected expert in the field of cements and she was an appropriate pick, having followed in Della Roy’s footsteps as the editor of the Cement and Concrete Research journal.

Scrivener is also the founder of Nanocem, a Europe-based initiative working on collaborative approaches (not just among institutions, but also between institutions and industry) to cements questions. One of the aims of Nanocem is to spur a constant effort to reduce CO₂ emissions:

“Evolving CO₂ emission caps in Europe mean that cement manufacturers will have to find solutions, or pay more to produce cement, which will reduce their competitivity. Nanocem is sponsoring fundamental research that will support technological solutions, not only to help secure the long-term health of the European cement industry, but also to address global CO₂ reduction by ensuring that cement manufacturing is not just shifted to regions of the world that have less stringent emissions regulations.”

The title of Scrivener’s Della Roy Lecture was “Modeling Hydration Kinetics of Cementitious Systems,” which was quite a good discussion about the what has and what’s yet to be done in the world of modeling cement microstructures.

But, as a non-expert in cements, I found Scrivener’s opening remarks, which provided the context for her technical presentation, a balanced and compelling discussion about the importance of cements and concrete to, well … the world!

A few of her salient points:

• Concrete is most used material in the world. It is the only material that can satisfy the demand for low-cost decent housing and infrastructure. There is no way to satisfy the demand for low-cost housing and infrastructure without concrete.

• The demand for concrete is growing and will continue to soar, especially in the developing nations. The demand may double or triple by 2050.

• Although cement production is energy intensive, the energy and CO₂ emissions of concrete (per ton) is among the lowest of all building materials, even lower than wood.

• The CO₂ problem associated with cements (5-8% of CO₂ production world wide) is primarily because of the volume of demand.

• There has been talk of achieving 5-10% reduction in emissions per cubic meter of concrete through the use of substitutes for Portland cement. It may be more like 1-2% given the amounts and choices of supplements (see below), but even a 1% saving would be equal to removing all the CO₂ emissions associated with steel production. “So that shows how much impact we can have by research to increase the sustainability of cement,” she said.

• The available elements in the earth’s crust imposes a fundamental limit on the options for substitute cementitious materials. Eight elements—oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium—make up 98 percent of earths crust. So, forget about making cement out of any other elements.

• The way this has been pursued over the last 20-some years is first of all process optimization. Cement kiln and other production operations have gotten much better and state-of-the-art plants are achieving 80% of their theoretical efficiency.

• So, recently the goal has shifted more to reducing the “clinker factor,” i.e., instead of grinding clinker and gypsum, add more and more supplementary cementitious materials. SCMs my be byproducts or waste products from other industries, such as limestone, fly ash, blast furnace slag, silica flume, natural pozzolans, etc.

• This has been a good and successful strategy (over the last 20 years 25% of the previous amount of clinker in cements is now substituted by SCMs).

• But … and this is a big “but” … this is going to be a difficult strategy going forward because under the best of circumstances, the amount of SCM available will be dwarfed by amount of cement produced.

• For example, people talk about using fly ash as an SCM and it is probably the most widely available. But, there simply isn’t enough fly ash worldwide to replace cement in any big amount. The availability of SCMs in underdeveloped countries, where the demand is going to be coming from, is small because by definition they don’t have the scale of industries to provide large volumes of slag and fly ash byproducts.

• So where are SCMs going to come from? More limestone, probably, but more calcined clays and natural pozzolans. Cuba may be a good source of calcined clays.

• There is no one single answer. All sustainability possibilities must be pursued in parallel. Eventually we are going to see a very diverse range of cements, which are adapted to locally available materials. But diversity means performance questions will be more and more complicated.

• For researchers to support sustainability, they must provide end users of concrete information that will make them confident about the use of the SCMs. This means having relevant performance tests. In particular, researchers need to know how to start with the variables—the composition of the cements, the SCMs, mixing techniques, curing times, relative humidities, etc.— and from this predict performance.

• Short term performance can be relatively easy to predict in the laboratory, but long term performance—where we expect structures to last 40-50 years without hardly any maintenance—is much harder to measure in the lab.

• Therefore, researchers have to pursue mechanisms to predict microstructure via advanced modeling techniques to pull all of this complex information together and have it make sense.

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Sun-free photovoltaics: Silicon chip micro-reactors contain photonic crystals on both flat faces, with external tubes for injecting fuel and air and ejecting waste products. In use, these reactors would have a photovoltaic cell mounted against each face to convert the emitted wavelengths of light to electricity. Credit: Justin Knight, MIT.

Check ‘em out:

• Uh oh, math error: BE Resources down nearly 75% as releases corrected rare earth assay results

• Google embraces solar skylight from EnFocus

• Caltech engineers develop one-way transmission system for sound waves

• Caltech, Zcube collaboration will bring painless transdermal drug delivery to patients

• Soft memory device opens door to new biocompatible electronics

• Sun-free photovoltaics: Materials engineered to give off precisely tuned wavelengths of light when heated are key to new high-efficiency generating system.

• Inside the innards of a nuclear reactor: Tiny robots may monitor underground pipes for radioactive leaks.

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Mechanical engineer Curt Freedman modified a foam drink cooler to make a courtroom apparatus to demonstrate heat flow and measure the extent to which ceramic-containing “insulating paint” provided the R-values advertised. It didn’t. Credit: Curt Freedman.

Shortly after I joined the ACerS staff (early 2008), I received a call from a reporter investigating the purported benefits of a type of paint that was being touted as having a high R-value because its maker had added “insulating” ceramic particles. The reporter’s too-good-to-be true antennae had him on alert that something was fishy and that the distributor of the high-priced product had been playing something of a Three-card Monte game on him, swapping terms like insulation, reflectivity and emissivity as if they were peas under walnut shells.

The reporter sent me a copy of the distributor’s promo piece and the URL of the company’s website. Eventually, I was able to provide a brief explanation of the three terms and why the paint’s claims were outlandish and bogus.

But, I still get inquiries about “insulating” paint several times a year, usually from people connected with architecture, wondering what the official verdict is regarding the insulative value of ceramic-containing paint. So, I know the hucksters are out there still looking for suckers.

Thus, I was filled with glee when a family member forwarded me this story by Martin Holladay about how a distributor of Super Therm, Alton King, was hoisted on his own petard:

King directed workers to apply Super Therm paint to multiple surfaces: the underside of the roof sheathing, the roof rafters, the exposed ceiling joists in the attic, and both sides of the ceiling drywall facing the attic. The worthless paint was also applied to the interior side of the wall sheathing and the exterior side of the Sheetrock on the walls. King claimed that the Super Therm paint would provide an overall insulating value of more than R-19 for the walls and more than R-38 for the ceilings. Since the stud bays and joist cavities of King’s home were empty, however, the actual R-value of his wall assembly was about R-2.9, while his ceilings had an R-value of only R-1.7.

… Soon after his new home was completed in June 2004, King moved in. Almost immediately, King began complaining of comfort problems. The temperature in the second-floor room was often above 90°F, even though the air-conditioner was running full tilt.

During the winter, the situation worsened. According to Associate Justice Robert Fields, who adjudicated the resulting lawsuit, “Believing the HVAC system responsible for the temperature problems, King contacted Dee. … After a multitude of complaints and repair requests, … Dee determined that the temperature problems in the home were not related to the HVAC system. Rather, Tetro informed King that the temperature problems were caused by inadequate insulation.”

At that point King contacted Curt Freedman, a mechanical engineer, and asked him to figure out why his house was so hard to heat and cool. Freedman later wrote, “During one of my site visits, with outside temperatures of 28ºF, temperatures in the home were noted only to be in the 48ºF to 60ºF range.”

… With his heating and cooling problems still unresolved, King decided to build an addition to his new home, increasing the size of his home from 7,291 square feet to 9,563 square feet.

This time, the town building department insisted that the walls and ceiling of the new addition had to include insulation. King complied, although he didn’t install any insulation in the older part of the house.

King decided to solve his comfort problem by installing a bigger boiler. “He installed a new 400,000 Btuh boiler, at a cost of over $100,000, even though he had previously submitted that the design heat load was 50,000 Btuh,” said Freedman. “The cost of the new HVAC system was much more than it would have cost to insulate the house.”

A disinterested observer might imagine that it was time for King to sue the manufacturer of Super Therm for false claims. But King had a different idea: he sued the HVAC contractor … King’s lawsuit was heard by Associate Justice Robert Fields, presiding without a jury. Freedman ended up testifying for the defendant - that is, the HVAC contractor. To demonstrate that Super Therm is ineffective at slowing heat flow, Freedman brought a modified beer cooler to court. The cooler included a 50-watt heater and a computer fan to maintain an evenly distributed temperature. “He had cut out a window in the foam box,” Harley recalled. “He had plugged the window with a film of dried paint. He peeled the dried paint off a paint roller tray. He didn’t try to make a quantitative measurement of the R-value of the paint. He just pointed an infrared scanner at the box and showed the difference in temperature between the outside of the insulated box and the window covered with dried paint film. It wasn’t an ASTM test, but the demonstration was valuable.”

Freedman helped convince the court that the HVAC contractor was not at fault. On June 8, 2011, the judge ruled in favor of the HVAC contractor. “Based on the evidence presented, I find it entirely plausible that had King’s house been insulated with traditional material, that a significant portion of the heat generated by the boiler and the cold air generated by the air conditioner would have remained in the home,” Justice Fields ruled. “Based on the foregoing, judgment shall enter in favor of the defendant, Dee Services, Inc.”

As straightforward as all of this might seem from a science and engineering point a view, Freedman told me that his testimony took over eight hours. (Also, Freedman laughed when he mentioned that because his apparatus, pictured above, could appear to be “alarmingly dangerous” to courthouse security officials, he had to give plenty of advanced warning to court staff and his personal assurance to the judge.)

I highly recommend reading Holladay’s whole story. As he notes, there is some poetic justice here. But this story makes me wonder, if this guy could afford to build a 9,500-square-foot home, it suggests that he was quite good at spinning his tales and finding gullible buyers for the $200-per-gallon paint.

With all the great things happening in ceramics and glass, it’s unfortunate to have our field be stained by apparent hucksters, such as King and Super Therm.

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Depiction of the essential functioning of the lithium-air battery. Ions of Li combine with oxygen from the air to form particles of Li oxides, which attach themselves to carbon fibers on the electrode as the battery is being used. During recharging, the Li oxides separate again into Li and oxygen and the process can begin again. Credit: Mitchell, Gallant and Shao-Horn; MIT.

An elusive piece of the alternative energy puzzle has been storage: How does one save it for when it’s needed or carry it around to use where it’s needed? In both cases, energy density is the key parameter and in the latter case, weight matters, too.

We’ve been following MIT associate professor Yang Shao-Horn and her work on lithium-air batteries in posts about alternative catalyst materials and carbon nanotube electrodes. Her group appears to have taken a leap forward in increasing the energy density using aligned carbon nanofiber electrodes that can store four times as much energy on a weight basis than current-technology Li-ion battery electrodes.

The lightweight advantage of lithium-air batteries (or any metal-air battery) comes from replacing a solid electrode like those in typical Li-ion batteries with a porous carbon electrode. Energy is stored when Li ions react with air flowing through the porosity to form Li oxides. The more porous the carbon, the more efficiently Li oxides are stored.

As the battery is used, particles of lithium peroxide form as small dots on the sides of carbon nanofibers (top), and become larger toroidal shapes as the battery discharges (bottom), as seen in these SEM images. Credit: Mitchell, Gallant, and Shao-Horn; MIT

A press release reports that Shao-Horn’s group used chemical vapor deposition to fabricate an electrode of vertically aligned arrays of carbon nanofibers with 90 percent void space, a big increase over the 70 percent void space the group reported achieving last year.

“We were able to create a novel carpet-like material-composed of more than 90 percent void space-that can be filled by the reactive material during battery operation,” Shao-Horn says in the press release. That means, according to Robert Mitchell, a graduate student and paper’s first author, that “the carpet-like arrays provide a highly conductive, low-density scaffold for energy storage.”

The gravimetric energy, which is the amount of power that can be stored for a given weight, for these very-low-density electrodes is one of the highest reported to date and demonstrates that “tuning the carbon structure is a promising route for increasing the energy density of lithium-air batteries,” said another graduate student and coauthor, Betar Gallant.

An unexpected finding is that the orderly “carpet” structure of the fibers makes them relatively easy to observe in a scanning electron microscope, and the performance of the electrodes can be monitored at intermediate states of charge. Being able to directly observe the process may shed some light on other vexing issues, such as the degradation observed after many charge–discharge cycles.

These latest results will be published in the August issue of the journal Energy and Environmental Science (see “All-carbon-nanofiber electrodes for high-energy rechargeable Li-O₂ batteries,” doi: 10.1039/C1EE01496J).

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Government agencies are starting to drive the Advanced Manufacturing Partnership announced in June by President Obama (see our earlier post about his announcement at Carnegie Mellon).

NIST is seeking comments from the public on the best way to structure its proposed Advanced Manufacturing Technology Consortium.

From NIST:

Contact: Barbara Lambis
301-975-4447

A notice published today by the National Institute of Standards and Technology (NIST) in the Federal Register requests opinions from the public about the best ways to structure a proposed new Advanced Manufacturing Technology Consortia (AMTech) Program.

First described in the President’s fiscal year 2012 budget request for NIST, the AMTech Program is a new public-private partnership initiative that would provide federal grants to leverage existing consortia or establish new ones focused on long-term industrial research needs. The grants would fund development of research road maps and projects in advanced manufacturing and enhance the research productivity of consortia members through improved coordination and efficiencies. The program’s goal is to accelerate the innovation process-discovery to invention to development of new manufacturing process technologies-that creates skilled, high-wage manufacturing jobs.

The Request for Information (RFI) asks interested parties to answer 26 questions about eligibility for consortia membership, selection criteria for research funds, best practices for maximizing small business participation or disseminating results, and a number of other topics.

Comments will be accepted by email only to AMtechRFC@nist.gov through Sept. 20, 2011. All comments will be made publicly available.

For further information, see the full Federal Register notice at http://www.gpo.gov/fdsys/pkg/FR-2011-07-22/pdf/2011-18580.pdf and the description of the AMTech Program in NIST’s fiscal year 2012 budget request (pages 250 to 254) at: http://www.osec.doc.gov/bmi/budget/12CJ/2012_NIST_&_NTIS_Cong_Budget.pdf

Additional Contact: Michael Walsh, (301) 975-5545

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