Tag Archives: shells

Making better concrete by looking to nature for inspiration

Researchers from the Masssachusetts Institute of Technology (MIT) are working on a new formula for concrete based on bones, shells, and other such natural materials. From a May 25, 2016 news item on Nanowerk (Note: A link has been removed),

Researchers at MIT are seeking to redesign concrete — the most widely used human-made material in the world — by following nature’s blueprints.

In a paper published online in the journal Construction and Building Materials (“Roadmap across the mesoscale for durable and sustainable cement paste – A bioinspired approach”), the team contrasts cement paste — concrete’s binding ingredient — with the structure and properties of natural materials such as bones, shells, and deep-sea sponges. As the researchers observed, these biological materials are exceptionally strong and durable, thanks in part to their precise assembly of structures at multiple length scales, from the molecular to the macro, or visible, level.

A May 26, 2016 MIT news release (also on EurekAlert), which originated the news item, provides more detail,

From their observations, the team, led by Oral Buyukozturk, a professor in MIT’s Department of Civil and Environmental Engineering (CEE), proposed a new bioinspired, “bottom-up” approach for designing cement paste.

“These materials are assembled in a fascinating fashion, with simple constituents arranging in complex geometric configurations that are beautiful to observe,” Buyukozturk says. “We want to see what kinds of micromechanisms exist within them that provide such superior properties, and how we can adopt a similar building-block-based approach for concrete.”

Ultimately, the team hopes to identify materials in nature that may be used as sustainable and longer-lasting alternatives to Portland cement, which requires a huge amount of energy to manufacture.

“If we can replace cement, partially or totally, with some other materials that may be readily and amply available in nature, we can meet our objectives for sustainability,” Buyukozturk says.

“The merger of theory, computation, new synthesis, and characterization methods have enabled a paradigm shift that will likely change the way we produce this ubiquitous material, forever,” Buehler says. “It could lead to more durable roads, bridges, structures, reduce the carbon and energy footprint, and even enable us to sequester carbon dioxide as the material is made. Implementing nanotechnology in concrete is one powerful example [of how] to scale up the power of nanoscience to solve grand engineering challenges.”

From molecules to bridges

Today’s concrete is a random assemblage of crushed rocks and stones, bound together by a cement paste. Concrete’s strength and durability depends partly on its internal structure and configuration of pores. For example, the more porous the material, the more vulnerable it is to cracking. However, there are no techniques available to precisely control concrete’s internal structure and overall properties.

“It’s mostly guesswork,” Buyukozturk says. “We want to change the culture and start controlling the material at the mesoscale.”

As Buyukozturk describes it, the “mesoscale” represents the connection between microscale structures and macroscale properties. For instance, how does cement’s microscopic arrangement affect the overall strength and durability of a tall building or a long bridge? Understanding this connection would help engineers identify features at various length scales that would improve concrete’s overall performance.

“We’re dealing with molecules on the one hand, and building a structure that’s on the order of kilometers in length on the other,” Buyukozturk says. “How do we connect the information we develop at the very small scale, to the information at the large scale? This is the riddle.”

Building from the bottom, up

To start to understand this connection, he and his colleagues looked to biological materials such as bone, deep sea sponges, and nacre (an inner shell layer of mollusks), which have all been studied extensively for their mechanical and microscopic properties. They looked through the scientific literature for information on each biomaterial, and compared their structures and behavior, at the nano-, micro-, and macroscales, with that of cement paste.

They looked for connections between a material’s structure and its mechanical properties. For instance, the researchers found that a deep sea sponge’s onion-like structure of silica layers provides a mechanism for preventing cracks. Nacre has a “brick-and-mortar” arrangement of minerals that generates a strong bond between the mineral layers, making the material extremely tough.

“In this context, there is a wide range of multiscale characterization and computational modeling techniques that are well established for studying the complexities of biological and biomimetic materials, which can be easily translated into the cement community,” says Masic.

Applying the information they learned from investigating biological materials, as well as knowledge they gathered on existing cement paste design tools, the team developed a general, bioinspired framework, or methodology, for engineers to design cement, “from the bottom up.”

The framework is essentially a set of guidelines that engineers can follow, in order to determine how certain additives or ingredients of interest will impact cement’s overall strength and durability. For instance, in a related line of research, Buyukozturk is looking into volcanic ash [emphasis mine] as a cement additive or substitute. To see whether volcanic ash would improve cement paste’s properties, engineers, following the group’s framework, would first use existing experimental techniques, such as nuclear magnetic resonance, scanning electron microscopy, and X-ray diffraction to characterize volcanic ash’s solid and pore configurations over time.

Researchers could then plug these measurements into models that simulate concrete’s long-term evolution, to identify mesoscale relationships between, say, the properties of volcanic ash and the material’s contribution to the strength and durability of an ash-containing concrete bridge. These simulations can then be validated with conventional compression and nanoindentation experiments, to test actual samples of volcanic ash-based concrete.

Ultimately, the researchers hope the framework will help engineers identify ingredients that are structured and evolve in a way, similar to biomaterials, that may improve concrete’s performance and longevity.

“Hopefully this will lead us to some sort of recipe for more sustainable concrete,” Buyukozturk says. “Typically, buildings and bridges are given a certain design life. Can we extend that design life maybe twice or three times? That’s what we aim for. Our framework puts it all on paper, in a very concrete way, for engineers to use.”

This is not the only team looking at new methods for producing the material, my Dec. 24, 2012 posting features a number of ‘concrete’ research projects.

Also, I highlighted the reference to ‘volcanic ash’ as it reminded me of Roman concrete which has lasted for over 2000 years and includes volcanic sand and volcanic rock.  You can read more about it in a Dec. 18, 2014 article by Mark Miller for Ancient Origins where he describes the wonders of the material and what was then a recent discovery of the Romans’ recipe.

I have two links and citations, first, the MIT paper, then the paper on Roman concrete.

Roadmap across the mesoscale for durable and sustainable cement paste – A bioinspired approach by Steven D. Palkovic, Dieter B. Brommer, Kunal Kupwade-Patil, Admir Masic, Markus J. Buehler, Oral Büyüköztürk.Construction and Building Materials Volume 115, 15 July 2016, Pages 13–31.  doi:10.1016/j.conbuildmat.2016.04.020

Mechanical resilience and cementitious processes in Imperial Roman architectural mortar by Marie D. Jackson, Eric N. Landis, Philip F. Brune, Massimo Vitti, Heng Chen, Qinfei Li, Martin Kunz, Hans-Rudolf Wenk, Paulo J. M. Monteiro, and Anthony R. Ingraffea. Proceedings of the National Academy of Sciences  vol. 111 no. 52 18484–18489, doi: 10.1073/pnas.1417456111

The first paper is behind a paywall but the second one appears to be open access.

Blue-striped limpets and their nanophotonic features

This is a structural colour story limpets and the Massachusetts Institute of Technology (MIT) and Harvard University. For the impatient here’s a video summary of the work courtesy of the researchers,

A Feb. 26, 2015 news item on ScienceDaily reiterates the details for those who like to read their science,

The blue-rayed limpet is a tiny mollusk that lives in kelp beds along the coasts of Norway, Iceland, the United Kingdom, Portugal, and the Canary Islands. These diminutive organisms — as small as a fingernail — might escape notice entirely, if not for a very conspicuous feature: bright blue dotted lines that run in parallel along the length of their translucent shells. Depending on the angle at which light hits, a limpet’s shell can flash brilliantly even in murky water.

Now scientists at MIT and Harvard University have identified two optical structures within the limpet’s shell that give its blue-striped appearance. The structures are configured to reflect blue light while absorbing all other wavelengths of incoming light. The researchers speculate that such patterning may have evolved to protect the limpet, as the blue lines resemble the color displays on the shells of more poisonous soft-bodied snails.

A Feb. 26, 2015 MIT news release (also on EurekAlert), which originated the news item, explains why this discovery is special,

The findings, reported this week in the journal Nature Communications, represent the first evidence of an organism using mineralized structural components to produce optical displays. While birds, butterflies, and beetles can display brilliant blues, among other colors, they do so with organic structures, such as feathers, scales, and plates. The limpet, by contrast, produces its blue stripes through an interplay of inorganic, mineral structures, arranged in such a way as to reflect only blue light.

The researchers say such natural optical structures may serve as a design guide for engineering color-selective, controllable, transparent displays that require no internal light source and could be incorporated into windows and glasses.

“Let’s imagine a window surface in a car where you obviously want to see the outside world as you’re driving, but where you also can overlay the real world with an augmented reality that could involve projecting a map and other useful information on the world that exists on the other side of the windshield,” says co-author Mathias Kolle, an assistant professor of mechanical engineering at MIT. “We believe that the limpet’s approach to displaying color patterns in a translucent shell could serve as a starting point for developing such displays.”

The news release then reveals how this research came about,

Kolle, whose research is focused on engineering bioinspired, optical materials — including color-changing, deformable fibers — started looking into the optical features of the limpet when his brother Stefan, a marine biologist now working at Harvard, brought Kolle a few of the organisms in a small container. Stefan Kolle was struck by the mollusk’s brilliant patterning, and recruited his brother, along with several others, to delve deeper into the limpet shell’s optical properties.

To do this, the team of researchers — which also included Ling Li and Christine Ortiz at MIT and James Weaver and Joanna Aizenberg at Harvard — performed a detailed structural and optical analysis of the limpet shells. They observed that the blue stripes first appear in juveniles, resembling dashed lines. The stripes grow more continuous as a limpet matures, and their shade varies from individual to individual, ranging from deep blue to turquoise.

The researchers scanned the surface of a limpet’s shell using scanning electron microscopy, and found no structural differences in areas with and without the stripes — an observation that led them to think that perhaps the stripes arose from features embedded deeper in the shell.

To get a picture of what lay beneath, the researchers used a combination of high-resolution 2-D and 3-D structural analysis to reveal the 3-D nanoarchitecture of the photonic structures embedded in the limpets’ translucent shells.

What they found was revealing: In the regions with blue stripes, the shells’ top and bottom layers were relatively uniform, with dense stacks of calcium carbonate platelets and thin organic layers, similar to the shell structure of other mollusks. However, about 30 microns beneath the shell surface the researchers noted a stark difference. In these regions, the researchers found that the regular plates of calcium carbonate morphed into two distinct structural features: a multilayered structure with regular spacing between calcium carbonate layers resembling a zigzag pattern, and beneath this, a layer of randomly dispersed, spherical particles.

The researchers measured the dimensions of the zigzagging plates, and found the spacing between them was much wider than the more uniform plates running through the shell’s unstriped sections. They then examined the potential optical roles of both the multilayer zigzagging structure and the spherical particles.

Kolle and his colleagues used optical microscopy, spectroscopy, and diffraction microscopy to quantify the blue stripe’s light-reflection properties. They then measured the zigzagging structures and their angle with respect to the shell surface, and determined that this structure is optimized to reflect blue and green light.

The researchers also determined that the disordered arrangement of spherical particles beneath the zigzag structures serves to absorb transmitted light that otherwise could de-saturate the reflected blue color.

From these results, Kolle and his team deduced that the zigzag pattern acts as a filter, reflecting only blue light. As the rest of the incoming light passes through the shell, the underlying particles absorb this light — an effect that makes a shell’s stripes appear even more brilliantly blue.

And, for those who can never get enough detail, the news release provides a bit more than the video,

The team then sought to tackle a follow-up question: What purpose do the blue stripes serve? The limpets live either concealed at the base of kelp plants, or further up in the fronds, where they are visually exposed. Those at the base grow a thicker shell with almost no stripes, while their blue-striped counterparts live higher on the plant.

Limpets generally don’t have well-developed eyes, so the researchers reasoned that the blue stripes must not serve as a communication tool, attracting one organism to another. Rather, they think that the limpet’s stripes may be a defensive mechanism: The mollusk sits largely exposed on a frond, so a plausible defense against predators may be to appear either invisible or unappetizing. The researchers determined that the latter is more likely the case, as the limpet’s blue stripes resemble the patterning of poisonous marine snails that also happen to inhabit similar kelp beds.

Kolle says the group’s work has revealed an interesting insight into the limpet’s optical properties, which may be exploited to engineer advanced transparent optical displays. The limpet, he points out, has evolved a microstructure in its shell to satisfy an optical purpose without overly compromising the shell’s mechanical integrity. Materials scientists and engineers could take inspiration from this natural balancing act.

“It’s all about multifunctional materials in nature: Every organism — no matter if it has a shell, or skin, or feathers — interacts in various ways with the environment, and the materials with which it interfaces to the outside world frequently have to fulfill multiple functions simultaneously,” Kolle says. “[Engineers] are more and more focusing on not only optimizing just one single property in a material or device, like a brighter screen or higher pixel density, but rather on satisfying several … design and performance criteria simultaneously. We can gain inspiration and insight from nature.”

Peter Vukusic, an associate professor of physics at the University of Exeter in the United Kingdom, says the researchers “have done an exquisite job” in uncovering the optical mechanism behind the limpet’s conspicuous appearance.

“By using multiple and complementary analysis techniques they have elucidated, in glorious detail, the many structural and physiological factors that have given rise to the optical signature of this highly evolved system,” says Vukusic, who was not involved in the study. “The animal’s complex morphology is highly interesting for photonics scientists and technologists interested in manipulating light and creating specialized appearances.”

Here’s a link to and a citation for the paper,

A highly conspicuous mineralized composite photonic architecture in the translucent shell of the blue-rayed limpet by Ling Li, Stefan Kolle, James C. Weaver, Christine Ortiz, Joanna Aizenberg & Mathias Kolle. Nature Communications 6, Article number: 6322 doi:10.1038/ncomms7322 Published 26 February 2015

This article is open access.

NanoStruck, an Ontario (Canada) water remediation and ‘mining’ company

Located in Mississauga, Ontario (Canada), Nanostruck’s Dec. 20, 2013 news release seems to be functioning as an announcement of its presence rather than any specific company developments,

NanoStruck has a suite of technologies that remove molecular sized particles using patented absorptive organic polymers. The company is sitting on some very incredible and environmently friendly technology.

Organic polymers are nature’s very own sponges. These versatile biomaterials are derived from crustacean shells or plant fibers, depending on requirements of their usage. Acting as molecular sponges, the nanometer-sized polymers are custom programmed toabsorb specific particles for remediation or retrieval purposes. These could be to clean out acids, hydrocarbons, pathogens, oils and toxins in water via its NanoPure solutions. Or to recover precious metal particles in mine tailings, such as gold, silver, platinum, palladium and rhodium using the Company’s NanoMet solutions.

By using patented modifications to conventional technologies and adding polymer-based nano-filtration, the Company’s offers environmentally safe NanoPure solutions for water purification. The Company uses Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines as a benchmark for water quality and safety to conform to acceptable agricultural or drinking water standards in jurisdictions where the technology is used. The worldwide shortage of cleanwater is highlighted on sites such as http://water.org/water-crisis/water-facts/water/.

The company’s NanoPure technology was first deployed to treat wastewater from a landfill site in January 2012 in Mexico. It has since been successfully treating and producing clean water there that’s certified by Conagua, the federal water commission of Mexico. The company has also created water treatment plants in Canada 

Additionally, the Company’s technology can be used to recover precious and base metals from mine tailings, which are the residual material from earlier mining activities. By retrieving valuable metals from old tailing dumps, the Company’s NanoMet solutions boosts the value of existing mining assets and reduces the need for new, costly and potentially environmentally harmful exploration and mining. 

There is an estimated $1 trillion worth of precious metals already extracted from the ground sitting in old mining sites that form our target market. We are in the process of deploying precious metal recovery plants in South Africa, Mexico and Canada.

The company is also developing new plant-based organic polymers to remove contaminants specific to the oil industry, such as naphthenic acids, which is a growing problem.

 Company information is available at www.nanostruck.ca and some description of the companies polymers are below

General Description of Nano Filtration Materials

Chitosan is a polysaccharide-based biomaterial derived from renewable feedstock such as the shells of crustaceans.  Chitosan displays limited adsorbent properties toward various types of contaminants (i.e. petrochemicals, pharmaceuticals, & agrochemicals).  By comparison, synthetically engineered biomaterials that utilize chitosan building blocks display remarkable sorption properties that are tunable toward various types of water borne contaminants.  Recent advances in materials science have enabled the development of Nano Filtration media with relative ease, low toxicity, and tunable molecular properties for a wide range of environmental remediation applications.  …

From what I can tell, the company has technology that can be used to remediate water (NanoPure) and, in the case of remediating mine tailings (NanoMet), allows for reclamation of the metals. It’s the kind of technology that can make you feel virtuous (reclaiming water) with the potential of paying you handsomely (reclaiming gold, etc.).

As I like to do from time to time, I followed the link to the water organization listed in the news release and found this on Water.org’s About Us page,

The water and sanitation problem in the developing world is far too big for charity alone. We are driving the water sector for new solutions, new financing models, greater transparency, and real partnerships to create lasting change. Our vision: Safe water and the dignity of a toilet for all, in our lifetime.

Co-founded by Matt Damon and Gary White, Water.org is a nonprofit organization that has transformed hundreds of communities in Africa, South Asia, and Central America by providing access to safe water and sanitation.

Water.org traces its roots back to the founding of WaterPartners International in 1990. In July 2009, WaterPartners merged with H2O Africa, resulting in the launch of Water.org. Water.org works with local partners to deliver innovative solutions for long-term success. Its microfinance-based WaterCredit Initiative is pioneering sustainable giving in the sector.

Getting back to NanoStruck, here’s more from their About page,

NanoStruck Technologies Inc. is a Canadian Company with a suite of technologies that remove molecular sized particles using patented absorptive organic polymers. These versatile biomaterials are derived from crustacean shells or plant fibers, depending on requirements of their usage. Acting as molecular sponges, the nanometer-sized polymers are custom programmed toabsorb specific particles for remediation or retrieval purposes. These could be to clean out acids, hydrocarbons, pathogens, oils and toxins in water via its NanoPure solutions. Or to recover precious metal particles in mine tailings, such as gold, silver, platinum, palladium and rhodium using the Company’s NanoMet solutions.

By using patented modifications to conventional technologies and adding polymer-based nano-filtration, the Company’s offers environmentally safe NanoPure solutions for water purification. The Company uses Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines as a benchmark for water quality and safety to conform to acceptable agricultural or drinking water standards in jurisdictions where the technology is used.

The Company’s current business model is based on either selling water remediation plants or leasing out units and charging customers on a price per liter basis with a negotiated minimum payment per annum. For processing mine tailings, the value of precious metal recovered is shared with tailing site owners on a pre-agreed basis.

I wonder if there are any research papers about the January 2012 work in Mexico. I find there is a dearth of technical information on the company’s website, which is somewhat unusual for a startup company (my experience is that they give you too much technical information in a fashion that is incomprehensible to anyone other than en expert). As well, I’m not familiar with any members of the company’s management team (Our Team webpage) but, surprisingly, there isn’t a Chief Science Officer or someone on the team from the science community. In fact, the entire team seems to have emerged from the business community. If I have time, I’ll see about getting an interview for publication here in 2014. In the meantime, it looks like a company with some interesting potential and I wish it well.

(Note: This is not endorsement or anti-endorsement of the company or its business. This is not my area of expertise.)

How to become a futurist; organic technology; clean water with carbon nanotubes

I’ve always wondered how futurists look into the future (and how do they get their jobs?). At last I’ve found the answer to my first question in an article by Jamais Cascio in Fast Company.

In this entry in the occasional series, we’ll take a look at gathering useful data.Like the first step, Asking the Question, Scanning the World seems like it would be easier than it really is. In my opinion, it may actually be the hardest step of all, because you have to navigate two seemingly contradictory demands:

  • You need to expand the horizons of your exploration, because the factors shaping how the future of the dilemma in question will manifest go far beyond the narrow confines of that issue.
  • You need to focus your attention on the elements critical to the dilemma, and not get lost in the overwhelming amount of information out there.

You should recognize up front that the first few times you do this, you’ll miss quite a few of the key drivers; even experienced futurists end up missing a some important aspects of a dilemma. It’s the nature of the endeavor: We can’t predict the future, but we can try to spot important signifiers of changes that will affect the future. We won’t spot them all, but the more we catch, the more useful our forecasts.

The process of opening up and narrowing simultaneously sounds similar to how any kind of research is done, that is, if it’s going to be groundbreaking.

There’s an announcement from India about a new energy-efficient single treatment water purification process. From the news item on Nanowerk,

Minister of Rural Water Supply, Hon. Minister Viswarup and other leaders in Hyderabad, India today. Initial tests, performed at Indian Institute of Technology (IIT) Kanpur, confirmed that the majority of the drinking water available in India contains toxins that can be extremely hazardous to human health. The technology developed in collaboration with IIT Kanpur and North Carolina-based Cnanoz can remove harmful pathogens and toxic ingredients, such as Arsenic, Fluoride, Lead, Cadmium, DDT, hydrocarbon wastes and nitrates in an eco-friendly and economical way. Drinking water contaminated with toxic chemicals over an extended period of time can promote harmful gene mutations that can cause neurological disorders, mental and physical disabilities. The preventive aspect of the filtration system can have a significant positive impact to improve public health survival and reduce health care costs.

No word on health and safety or environmental issues or any details about the technology can be found in the announcement so I looked on the website for the company (Cnanoz) that developed the product. Nothing much there either but it is slick and easily navigable.

I’ve gotten more interested in the interplay between organic and  inorganic materials and this research is quite intriguing to me. From the news item on Nanowerk,

Single crystals of the mineral calcite — the chief material in limestone — are predictable, homogeneous and, well, a little boring. But scientists have long marveled at how biological crystals of calcite grow together with other organic materials to form, for example, shells and sea urchin spines. Biologists and materials scientists would love to know exactly how to re-create such natural composites in the lab.

“We knew the organics were in there, but what no one had been able to do up until now was actually see what that organic-inorganic interface looked like,” said [Lara] Estroff [assistant professor of materials science and engineering], whose lab focuses on the synthesis and characterization of bio-inspired materials.

That’s it for today.