Tag Archives: cement

‘No kiln’ ceramics

Sometimes it’s hard to believe what one reads and this piece about ceramics made without kilns  (for me) fits into that category (from a Feb. 28, 2017 ETH Zurich [English: Swiss Federal Institute of Technology in Zurich] [German: Eidgenössische Technische Hochschule Zürich]) press release (also on EurekAlert) by Fabio Bergamin),

The manufacture of cement, bricks, bathroom tiles and porcelain crockery normally requires a great deal of heat: a kiln is used to fire the ceramic materials at temperatures well in excess of 1,000°C. Now, material scientists from ETH Zurich have developed what seems at first glance to be an astonishingly simple method of manufacture that works at room temperature. The scientists used a calcium carbonate nanopowder as the starting material and instead of firing it, they added a small amount of water and then compacted it.

“The manufacturing process is based on the geological process of rock formation,” explains Florian Bouville, a postdoc in the group of André Studart, Professor of Complex Materials. Sedimentary rock is formed from sediment that is compressed over millions of years through the pressure exerted by overlying deposits. This process turns calcium carbonate sediment into limestone with the help of the surrounding water. As the ETH researchers used calcium carbonate with an extremely fine particle size (nanoparticles) as the starting material, their compacting process took only an hour. “Our work is the first evidence that a piece of ceramic material can be manufactured at room temperature in such a short amount of time and with relatively low pressures,” says ETH professor Studart.

Stronger than concrete

As tests have shown, the new material can withstand about ten times as much force as concrete before it breaks, and is as stiff as stone or concrete. In other words, it is just as hard to deform.

So far, the scientists have produced material samples of about the size of a one-franc piece using a conventional hydraulic press such as those normally used in industry. “The challenge is to generate a sufficiently high pressure for the compacting process. Larger workpieces require a correspondingly greater force,” says Bouville. According to the scientists, ceramic pieces the size of small bathroom tiles should theoretically be feasible.

Energy-efficient and environmentally benign

“For a long time, material scientists have been searching for a way to produce ceramic materials under mild conditions, as the firing process requires a large amount of energy,” says Studart. The new room-temperature method – which experts refer to as cold sintering — is much more energy-efficient and also enables the production of composite materials containing, for example, plastic.

The technique is also of interest with a view to a future CO2-neutral society. Specifically, the carbonate nanoparticles could conceivably be produced using CO2 captured from the atmosphere or from waste gases from thermal power stations. In this scenario, the captured CO2 is allowed to react with a suitable rock in powder form to produce carbonate, which could then be used to manufacture ceramics at room temperature. The climate-damaging CO2 would thus be stored in ceramic products in the long term. These would constitute a CO2 sink and could help thermal power stations to operate on a carbon-neutral basis.

According to the scientists, in the long term, the new approach of cold sintering even has the potential to lead to more environmentally friendly substitutes for cement-based materials. However, great research efforts are needed to reach this goal. Cement production is not only energy-intensive, but it also generates large amounts of CO2 – unlike potential cold-sintered replacement materials.

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

Geologically-inspired strong bulk ceramics made with water at room temperature by Florian Bouville & André R. Studart. Nature Communications 8, Article number: 14655 (2017) doi:10.1038/ncomms14655 Published online: 06 March 2017

This paper is open access.

Florian Bouville’s work in ceramics was last mentioned here in a March 25, 2014 posting.

Kinetic properties of cement at the nanoscale

There was a Vancouver-born architect, Arthur Erickson, who adored concrete as a building material. In fact, he gained an international reputation for his ‘concrete’ work. I have never been a fan, especially after attending Simon Fraser University (one of Erickson’s early triumphs) in Vancouver (Canada) and experiencing the joy of deteriorating concrete structures.

This somewhat related news concerns cement, (from a Dec.7, 2016 news item on ScienceDaily,

Bringing order to disorder is key to making stronger and greener cement, the paste that binds concrete.

Scientists at Rice University have decoded the kinetic properties of cement and developed a way to “program” the microscopic, semicrystalline particles within. The process turns particles from disordered clumps into regimented cubes, spheres and other forms that combine to make the material less porous and more durable.

A Dec. 7, 2016 Rice University news release, which originated the news item, explains further (Note: Links have been removed),

The technique may lead to stronger structures that require less concrete – and less is better, said Rice materials scientist and lead author Rouzbeh Shahsavari. Worldwide production of more than 3 billion tons of concrete a year now emits as much as 10 percent of the carbon dioxide, a greenhouse gas, released to the atmosphere.

Through extensive experiments, Shahsavari and his colleagues decoded the nanoscale reactions — or “morphogenesis” — of the crystallization within calcium-silicate hydrate (C-S-H) cement that holds concrete together.

For the first time, they synthesized C-S-H particles in a variety of shapes, including cubes, rectangular prisms, dendrites, core-shells and rhombohedra and mapped them into a unified morphology diagram for manufacturers and builders who wish to engineer concrete from the bottom up.

“We call it programmable cement,” he said. “The great advance of this work is that it’s the first step in controlling the kinetics of cement to get desired shapes. We show how one can control the morphology and size of the basic building blocks of C-S-H so that they can self-assemble into microstructures with far greater packing density compared with conventional amorphous C-S-H microstructures.”

He said the idea is akin to the self-assembly of metallic crystals and polymers. “It’s a hot area, and researchers are taking advantage of it,” Shahsavari said. “But when it comes to cement and concrete, it is extremely difficult to control their bottom-up assembly. Our work provides the first recipe for such advanced synthesis.

“The seed particles form first, automatically, in our reactions, and then they dominate the process as the rest of the material forms around them,” he said. “That’s the beauty of it. It’s in situ, seed-mediated growth and does not require external addition of seed particles, as commonly done in the industry to promote crystallization and growth.”

Previous techniques to create ordered crystals in C-S-H required high temperatures or pressures, prolonged reaction times and the use of organic precursors, but none were efficient or environmentally benign, Shahsavari said.

The Rice lab created well-shaped cubes and rectangles by adding small amounts of positive or negative ionic surfactants and calcium silicate to C-S-H and exposing the mix to carbon dioxide and ultrasonic sound. The crystal seeds took shape around surfactant micelles within 25 minutes. Decreasing the calcium silicate yielded more spherical particles and smaller cubes, while increasing it formed clumped spheres and interlocking cubes.

Once the calcite “seeds” form, they trigger the molecules around them to self-assemble into cubes, spheres and other shapes that are orders of magnitude larger. These can pack more tightly together in concrete than amorphous particles, Shahsavari said. Carefully modulating the precursor concentration, temperature and duration of the reaction varies the yield, size and morphology of the final particles.

The discovery is an important step in concrete research, he said. It builds upon his work as part of the Massachusetts Institute of Technology team that decoded cement’s molecular “DNA” in 2009. “There is currently no control over C-S-H shape,” Shahsavari said. “The concrete used today is an amorphous colloid with significant porosity that entails reduced strength and durability.”

Concrete is one focus of Shahsavari’s Rice lab, which has studied both its macroscale manufacture and intrinsic nanoscale properties. Because concrete is the world’s most common construction material and a significant source of atmospheric carbon dioxide, he is convinced of the importance of developing “greener” concrete.

The new technique has several environmental benefits, Shahsavari said. “One is that you need less of it (the concrete) because it is stronger. This stems from better packing of the cubic particles, which leads to stronger microstructures. The other is that it will be more durable. Less porosity makes it harder for unwanted chemicals to find a path through the concrete, so it does a better job of protecting steel reinforcement inside.”

The research required the team to develop a method to test microscopic concrete particles for strength. The researchers used a diamond-tipped nanoindenter to crush single cement particles with a flat edge.

They programmed the indenter to move from one nanoparticle to the next and crush it and gathered mechanical data on hundreds of particles of various shapes in one run. “Other research groups have tested bulk cement and concrete, but no group had ever probed the mechanics of single C-S-H particles and the effect of shape on mechanics of individual particles,” Shahsavari said.

He said strategies developed during the project could have implications for other applications, including bone tissue engineering, drug delivery and refractory materials, and could impact such other complex systems as ceramics and colloids.

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

Morphogenesis of Cement Hydrate by Sakineh E Moghaddam, vahid hejazi, Sung Hoon Hwang, Sreeprasad Srinavasan, Joseph B. Miller, Benhang Shi, Shuo Zhao, Irene Rusakova, Aali R. Alizadeh, Kenton Whitmire and Rouzbeh Shahsavari. J. Mater. Chem. A, 2016, DOI: 10.1039/C6TA09389B First published online 30 Nov 2016

I believe this paper is behind a paywall.

Cellullose nanocrystals (CNC) and better concrete

Earlier this week in a March 30, 2015 post, I was bemoaning the dearth of applications for cellulose nanocrystals (CNC) with concomitant poor prospects for commercialization and problems for producers such as Canada’s CelluForce. Possibly this work at Purdue University (Indiana, US) will help address some of those issues (from a March 31, 2015 news item on Nanowerk),

Cellulose nanocrystals derived from industrial byproducts have been shown to increase the strength of concrete, representing a potential renewable additive to improve the ubiquitous construction material.

The cellulose nanocrystals (CNCs) could be refined from byproducts generated in the paper, bioenergy, agriculture and pulp industries. They are extracted from structures called cellulose microfibrils, which help to give plants and trees their high strength, lightweight and resilience. Now, researchers at Purdue University have demonstrated that the cellulose nanocrystals can increase the tensile strength of concrete by 30 percent.

A March 31, 2015 Purdue University news release by Emil Venere, which originated the news item, further describes the research published in print as of February 2015 (Note: A link has been removed),

One factor limiting the strength and durability of today’s concrete is that not all of the cement particles are hydrated after being mixed, leaving pores and defects that hamper strength and durability.

“So, in essence, we are not using 100 percent of the cement,” Zavattieri [Pablo Zavattieri, an associate professor in the Lyles School of Civil Engineering] said.

However, the researchers have discovered that the cellulose nanocrystals increase the hydration of the concrete mixture, allowing more of it to cure and potentially altering the structure of concrete and strengthening it.  As a result, less concrete needs to be used.

The cellulose nanocrystals are about 3 to 20 nanometers wide by 50-500 nanometers long – or about 1/1,000th the width of a grain of sand – making them too small to study with light microscopes and difficult to measure with laboratory instruments. They come from a variety of biological sources, primarily trees and plants.

The concrete was studied using several analytical and imaging techniques. Because chemical reactions in concrete hardening are exothermic, some of the tests measured the amount of heat released, indicating an increase in hydration of the concrete. The researchers also hypothesized the precise location of the nanocrystals in the cement matrix and learned how they interact with cement particles in both fresh and hardened concrete. The nanocrystals were shown to form little inlets for water to better penetrate the concrete.

The research dovetails with the goals of P3Nano, a public-private partnership supporting development and use of wood-based nanomaterial for a wide-range of commercial products.

“The idea is to support and help Purdue further advance the CNC-Cement technology for full-scale field trials and the potential for commercialization,” Zavattieri said.

The researchers have provided an image,

This transmission electron microscope image shows cellulose nanocrystals, tiny structures derived from renewable sources that might be used to create a new class of biomaterials with many potential applications. The structures have been shown to increase the strength of concrete. (Purdue Life Sciences Microscopy Center)

This transmission electron microscope image shows cellulose nanocrystals, tiny structures derived from renewable sources that might be used to create a new class of biomaterials with many potential applications. The structures have been shown to increase the strength of concrete. (Purdue Life Sciences Microscopy Center)

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

The influence of cellulose nanocrystal additions on the performance of cement paste by Yizheng Cao, Pablo Zavaterri, Jeff Youngblood, Robert Moon, and Jason Weiss. Cement and Concrete Composites, Volume 56, February 2015, Pages 73–83  DOI: 10.1016/j.cemconcomp.2014.11.008 Available online 18 November 2014

The paper is behind a paywall.

One final note, cellulose nanocrystals (CNC) may also be referred to nanocrystalline cellulose (NCC).

 

Cement and concrete festival

Over the last week or so there’ve been a number of articles and publications about cement and concrete and nanotechnology. The Dec. 17, 2012 Nanowerk Spotlight article by (Mohammed) Shakeel Iqbal and Yashwant Mahajan for India’s Centre for Knowledge Management of Nanoscience & Technology (CKMNT, an ARCI [International Advanced Research Centre for Powder Metallurgy and New Materials] project, Dept.of Science & Technology) seemed to kick off the trend with a patent analysis of nanotechnology-enabled cement innovations,

China is the world leader of patent filings, their 154 patent applications contributing 41% of overall filings, representing the major and active R&D player in the area of nano-based cementitious materials. South Korea is the second leading country with 55 patents (15% of patent filings) on nano-enabled cement, closely followed by United States with 51 patents. Russia, Germany, Japan, France and India are the other leading patent filing countries with 37, 18, 11, 9 and 5 patents respectively, while the remaining patents represent a minor contribution from rest of the world.

….

Dagestan State University (Russia) is the leading assignee with 15-patents to its credit, which are mainly focussed on the development of heat resistant and high compression strength concrete materials. Halliburton Energy Services Inc (USA) comes second with 14-patents that are directed towards well bore cementing for the gas, oil or water wells using nano-cementitious materials.

This is another teaser article from the CKMNT (see my Dec. 13, 2012 posting about their bio-pharmaceutical teaser article) that highlights the findings from a forthcoming report,

A comprehensive Market Research Report on “Nanotechnology in Cement Industry” is proposed to be released by CKMNT in the near future. Interested readers may please contact Dr. Y. R. Mahajan, Technical Adviser and Editor, Nanotech Insights or Mr. H. Purushotham, Team Leader purushotham@ckmnt.com.

Regardless of one’s feelings about patents and patent systems, the article also provides a  good technology overview of the various nanomaterials used as fillers in cement, courtesy of the information in the filed patents.

A December 20, 2012 news item on Azonano points to at least of the reasons cement is occasioning research interest,

Cement production is responsible for 5% of carbon dioxide emissions. If we are to invent a “green” cement, we need to understand in more detail the legendary qualities of traditional Portland cement. A research group partly financed by the Swiss National Science Foundation (SNSF) is tackling this task.

The Dec. 20, 2012 Swiss National Science Foundation (SNSF) news release, which originated the news item on Azonano, goes on to describe the research into exactly how Portland cement’s qualities are derived,

The researchers first developed a packing model of hydrated calcium silicate nanoparticles. They then devised a method for observing their precipitation based on numerical simulations. This approach has proven successful (*). “We were able to show that the different densities on the nano scale can be explained by the packing of nanoparticles of varying sizes. At this crucial level, the result is greater material hardness than if the particles were of the same size and it corresponds to the established knowledge that, at macroscopic level, aggregates of different sizes form a harder concrete.” [said Emanuela Del Gado, SNSF professor at the Institute for Building Materials of the ETH Zurich]

Until today, all attempts to reduce or partially replace burnt calcium carbonate in the production of cement have resulted in less material hardness. By gaining a better understanding of the mechanisms at the nano level, it is possible to identify physical and chemical parameters and to improve the carbon footprint of concrete without reducing its hardness.

For those of a more technical turn of mind, here’s a citation for the paper (from the SNSF press release),

E. Masoero, E. Del Gado, R. J.-M. Pellenq, F.-J. Ulm, and S. Yip (2012). Nanostructure and Nanomechanics of Cement: Polydisperse Colloidal Packing. Physical Review Letters. DOI: 10.1103/PhysRevLett.109.155503

Meanwhile, there’s a technical group in Spain working on ‘biological’ concrete. From the Dec. 20, 2012 news item on ScienceDaily,

In studying this concrete, the researchers at the Structural Technology Group of the Universitat Politècnica de Catalunya • BarcelonaTech (UPC) have focused on two cement-based materials. The first of these is conventional carbonated concrete (based on Portland cement), with which they can obtain a material with a pH of around 8. The second material is manufactured with a magnesium phosphate cement (MPC), a hydraulic conglomerate that does not require any treatment to reduce its pH, since it is slightly acidic.

On account of its quick setting properties, magnesium phosphate cement has been used in the past as a repair material. It has also been employed as a biocement in the field of medicine and dentistry, indicating that it does not have an additional environmental impact.

The innovative feature of this new (vertical multilayer) concrete is that it acts as a natural biological support for the growth and development of certain biological organisms, to be specific, certain families of microalgae, fungi, lichens and mosses.

Here’s a description of the ‘biological’ concrete and its layers,

In order to obtain the biological concrete, besides the pH, other parameters that influence the bioreceptivity of the material have been modified, such as porosity and surface roughness. The result obtained is a multilayer element in the form of a panel which, in addition to a structural layer, consists of three other layers: the first of these is a waterproofing layer situated on top of the structural layer, protecting the latter from possible damage caused by water seeping through.

The next layer is the biological layer, which supports colonisation and allows water to accumulate inside it. It acts as an internal microstructure, aiding retention and expelling moisture; since it has the capacity to capture and store rainwater, this layer facilitates the development of biological organisms.

The final layer is a discontinuous coating layer with a reverse waterproofing function. [emphasis mine] This layer permits the entry of rainwater and prevents it from escaping; in this way, the outflow of water is redirected to where it is aimed to obtain biological growth

This work is designed for a Mediterranean climate and definitely not for rain forests such as the Pacific Northwest which, climatologically, is a temperate rainforest.

The ScienceDaily news item ends with this information about future research and commercialization,

The research has led to a doctoral thesis, which Sandra Manso is writing. At present, the experimental campaign corresponding to the phase of biological growth is being conducted, and this will be completed at the UPC and the University of Ghent (Belgium). This research has received support from Antonio Gómez Bolea, a lecturer in the Faculty of Biology at the University of Barcelona, who has made contributions in the field of biological growth on construction materials.

At present, a patent is in the process of being obtained for this innovative product, and the Catalan company ESCOFET 1886 S.A., a manufacturer of concrete panels for architectural and urban furniture purposes, has already shown an interest in commercialising the material.

Almost at the same time, the US Transport Research Board (a division of the US National Research Council) released this Dec. 19, 2012 announcement about their latest circular,

TRB Transportation Research Circular E-C170: Nanotechnology in Concrete Materials: A Synopsis explore promising new research and innovations using nanotechnology that have the potential to result in improved mechanical properties, volume change properties, durability, and sustainability in concrete materials.

The report is 44 pp (PDF version) and provides an in-depth look (featuring some case studies) at the research not just of nanomaterials but also nanoelectronics and sensors as features in nanotechoology-enabled concrete and cement products.

There you have it, a festival of cement and concrete.

Nanotechnology-enabled mineral foam wins Cleantech award

The award is for developing a product which uses waste materials such as mine tailings, “high carbon” fly ash, etc. to create a composite which provides an alternative to cement. From the news item on Azonano,

ATI-Composites focuses on the development of light weight concrete or mineral foam which has the potential to impact the Autoclaved Aerated Concrete (AAC) market, the Structural Insulated Panels (SIP) market, as well as the pre-cast industry. The technology utilizes waste materials such as mine tailings, Class C, class F or “high carbon” fly ash, and/or agricultural waste such as rice hulls. The high strength, Fire Resistant nano-technology-based binder products (alternate to cement) can include ocean water use with no compromise in strength and performance. This is extremely significant with regard to water conservation and the reduction in GHG emissions as the emerging world transitions from rural to more urban population distribution.

You can find out more about the company here at its website. From the front page,

ATI-Composites is a privately owned, Canadian company dedicated to the research, development, production and code approvals of unique building products, systems and (fire retardant) components.

The company has operated in Edmonton, Alberta, Canada for over 12 years; the principals have been involved in product development, marketing and building code approvals for more than 20 years.

As for the competition (from the news item on Azonano),

The Clean 15 cleantech competition connects visionary large companies with Canadian cleantech opportunities. The relationships are intended to facilitate commercialization for Canada’s cleantech researchers and developers, as well as support and stimulate the country’s cleantech economy.