Category Archives: construction

Concrete collapse and research into durability

I have two items about concrete buildings, one concerns the June 24, 2021 collapse of a 12-storey condominium building in Surfside, close to Miami Beach in Florida. There are at least 20 people dead and, I believe, over 120 are still unaccounted for (July 2, 2021 Associated Press news item on Canadian Broadcasting Corporation news online website).

Miami collapse

Nate Berg’s June 25, 2021 article for Fast Company provides an instructive overview of the building collapse (Note: A link has been removed),

Why the building collapsed is not yet known [emphasis mine]. David Darwin is a professor of civil engineering at the University of Kansas and an expert in reinforced concrete structures, and he says the eventual investigation of the Surfside collapse will explore all the potential causes, ranging from movement in the foundation before the collapse, corrosion in the debris, and excessive cracking in the part of the building that remains standing. “There are all sorts of potential causes of failure,” Darwin says. “At this point, speculation is not helpful for anybody.”

Sometimes I can access the entire article, and at other times, only a few paragraphs; I hope you get access to all of it as it provides a lot of information.

The Surfside news puts this research from Northwestern University (Chicago, Illinois) into much sharper relief than might otherwise be the case. (Further on I have some information about the difference between cement and concrete and how cement leads to concrete.)

Smart cement for more durable roads and cities

Coincidentally, just days before the Miami Beach building collapse, a June 21, 2021 Northwestern University news release (also on EurekAlert), announced research into improving water and fracture resistance in cement,

Forces of nature have been outsmarting the materials we use to build our infrastructure since we started producing them. Ice and snow turn major roads into rubble every year; foundations of houses crack and crumble, in spite of sturdy construction. In addition to the tons of waste produced by broken bits of concrete, each lane-mile of road costs the U.S. approximately $24,000 per year to keep it in good repair.

Engineers tackling this issue with smart materials typically enhance the function of materials by increasing the amount of carbon, but doing so makes materials lose some mechanical performance. By introducing nanoparticles into ordinary cement, Northwestern University researchers have formed a smarter, more durable and highly functional cement.

The research was published today (June 21 [2021]) in the journal Philosophical Transactions of the Royal Society A.

With cement being the most widely consumed material globally and the cement industry accounting for 8% of human-caused greenhouse gas emissions, civil and environmental engineering professor Ange-Therese Akono turned to nanoreinforced cement to look for a solution. Akono, the lead author on the study and an assistant professor in the McCormick School of Engineering, said nanomaterials reduce the carbon footprint of cement composites, but until now, little was known about its impact on fracture behavior.

“The role of nanoparticles in this application has not been understood before now, so this is a major breakthrough,” Akono said. “As a fracture mechanics expert by training, I wanted to understand how to change cement production to enhance the fracture response.”

Traditional fracture testing, in which a series of light beams is cast onto a large block of material, involves lots of time and materials and seldom leads to the discovery of new materials.

By using an innovative method called scratch testing, Akono’s lab efficiently formed predictions on the material’s properties in a fraction of the time. The method tests fracture response by applying a conical probe with increasing vertical force against the surface of microscopic bits of cement. Akono, who developed the novel method during her Ph.D. work, said it requires less material and accelerates the discovery of new ones.

“I was able to look at many different materials at the same time,” Akono said. “My method is applied directly at the micrometer and nanometer scales, which saves a considerable amount of time. And then based on this, we can understand how materials behave, how they crack and ultimately predict their resistance to fracture.”

Predictions formed through scratch tests also allow engineers to make changes to materials that enhance their performance at the larger scale. In the paper, graphene nanoplatelets, a material rapidly gaining popularity in forming smart materials, were used to improve the resistance to fracture of ordinary cement. Incorporating a small amount of the nanomaterial also was shown to improve water transport properties including pore structure and water penetration resistance, with reported relative decreases of 76% and 78%, respectively.

Implications of the study span many fields, including building construction, road maintenance, sensor and generator optimization and structural health monitoring.

By 2050, the United Nations predicts two-thirds of the world population will be concentrated in cities. Given the trend toward urbanization, cement production is expected to skyrocket.

Introducing green concrete that employs lighter, higher-performing cement will reduce its overall carbon footprint by extending maintenance schedules and reducing waste.

Alternately, smart materials allow cities to meet the needs of growing populations in terms of connectivity, energy and multifunctionality. Carbon-based nanomaterials including graphene nanoplatelets are already being considered in the design of smart cement-based sensors for structural health monitoring.

Akono said she’s excited for both follow-ups to the paper in her own lab and the ways her research will influence others. She’s already working on proposals that look into using construction waste to form new concrete and is considering “taking the paper further” by increasing the fraction of nanomaterial that cement contains.

“I want to look at other properties like understanding the long-term performance,” Akono said. “For instance, if you have a building made of carbon-based nanomaterials, how can you predict the resistance in 10, 20 even 40 years?”

The study, “Fracture toughness of one- and two-dimensional nanoreinforced cement via scratch testing,” was supported by the National Science Foundation Division of Civil, Mechanical and Manufacturing Innovation (award number 18929101).

Akono will give a talk on the paper at The Royal Society’s October [2021] meeting, “A Cracking Approach to Inventing Tough New Materials: Fracture Stranger Than Friction,” which will highlight major advances in fracture mechanics from the past century.

I don’t often include these kinds of photos (one or more of the researchers posing (sometimes holding something) for the camera but I love the professor’s first name, Ange-Therese (which means angel in French, I don’t know if she ever uses the French spelling for Thérèse),

Caption: Professor Ange-Therese Akono holds a sample of her smart cement. Credit: Northwestern University

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

Fracture toughness of one- and two-dimensional nanoreinforced cement via scratch testing by Ange-Therese Akono. Philosophical Transactions of the Royal Society A: Mathematical, Physical & Engineering Sciences 2021 379 (2203): 20200288 DOI: 10.1098/rsta.2020.0288 Published June 21, 2021

This paper appears to be open access.

Cement vs. concrete

Andrew Logan’s April 3, 2020 article for MIT (Massachusetts Institute of Technology) News is a very readable explanation of how cement and concrete differ and how they are related,

There’s a lot the average person doesn’t know about concrete. For example, it’s porous; it’s the world’s most-used material after water; and, perhaps most fundamentally, it’s not cement.

Though many use “cement” and “concrete” interchangeably, they actually refer to two different — but related — materials: Concrete is a composite made from several materials, one of which is cement. [emphasis mine]

Cement production begins with limestone, a sedimentary rock. Once quarried, it is mixed with a silica source, such as industrial byproducts slag or fly ash, and gets fired in a kiln at 2,700 degrees Fahrenheit. What comes out of the kiln is called clinker. Cement plants grind clinker down to an extremely fine powder and mix in a few additives. The final result is cement.

“Cement is then brought to sites where it is mixed with water, where it becomes cement paste,” explains Professor Franz-Josef Ulm, faculty director of the MIT Concrete Sustainability Hub (CSHub). “If you add sand to that paste it becomes mortar. And if you add to the mortar large aggregates — stones of a diameter of up to an inch — it becomes concrete.”

Final thoughts

I offer my sympathies to the folks affected by the building collapse and my hopes that research will lead the way to more durable cement and, ultimately, concrete buildings.

Stronger concrete with graphene derived from tires

I’ve become strangely fascinated with concrete these last few months. Possibly, this is a consequence of a lot more ‘concrete’ research being published. Here’s a March 29, 2021 news item on phys.org featuring work from Rice University (Texas, US),

This could be where the rubber truly hits the road.

Rice University scientists have optimized a process to convert waste from rubber tires into graphene that can, in turn, be used to strengthen concrete.

The environmental benefits of adding graphene to concrete are clear, chemist James Tour said.

“Concrete is the most-produced material in the world, and simply making it produces as much as 9% of the world’s carbon dioxide emissions,” Tour said. “If we can use less concrete in our roads, buildings and bridges, we can eliminate some of the emissions at the very start.”

A March 29, 2021 Rice University news release (also on EurekAlert), which originated the news item, provides context for the work and more technical details,

Recycled tire waste is already used as a component of Portland cement, but graphene has been proven to strengthen cementitious materials, concrete among them, at the molecular level.

While the majority of the 800 million tires discarded annually are burned for fuel or ground up for other applications, 16% of them wind up in landfills.

“Reclaiming even a fraction of those as graphene will keep millions of tires from reaching landfills,” Tour said.

The “flash” process introduced by Tour and his colleagues in 2020 has been used to convert food waste, plastic and other carbon sources by exposing them to a jolt of electricity that removes everything but carbon atoms from the sample.

Those atoms reassemble into valuable turbostratic graphene, which has misaligned layers that are more soluble than graphene produced via exfoliation from graphite. That makes it easier to use in composite materials.

Rubber proved more challenging than food or plastic to turn into graphene, but the lab optimized the process by using commercial pyrolyzed waste rubber from tires. After useful oils are extracted from waste tires, this carbon residue has until now had near-zero value, Tour said.

Tire-derived carbon black or a blend of shredded rubber tires and commercial carbon black can be flashed into graphene. Because turbostratic graphene is soluble, it can easily be added to cement to make more environmentally friendly concrete.

The research led by Tour and Rouzbeh Shahsavari of C-Crete Technologies is detailed in the journal Carbon.

The Rice lab flashed tire-derived carbon black and found about 70% of the material converted to graphene. When flashing shredded rubber tires mixed with plain carbon black to add conductivity, about 47% converted to graphene. Elements besides carbon were vented out for other uses.

The electrical pulses lasted between 300 milliseconds and 1 second. The lab calculated electricity used in the conversion process would cost about $100 per ton of starting carbon.

The researchers blended minute amounts of tire-derived graphene — 0.1 weight/percent (wt%) for tire carbon black and 0.05 wt% for carbon black and shredded tires — with Portland cement and used it to produce concrete cylinders. Tested after curing for seven days, the cylinders showed gains of 30% or more in compressive strength. After 28 days, 0.1 wt% of graphene sufficed to give both products a strength gain of at least 30%.

“This increase in strength is in part due to a seeding effect of 2D graphene for better growth of cement hydrate products, and in part due to a reinforcing effect at later stages,” Shahsavari said.

Set of tires on a sky background

I’m not sure where I got this stock shot but it is pretty (if tires can ever be described that way).

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

Flash Graphene from Rubber Waste by Paul A. Advincula, Duy Xuan Luong, Weiyin Chen, Shivaranjan Raghuraman, Rouzbeh Shahsavari, James M.Tour. Carbon Available online 28 March 2021 In Press, Journal Pre-proof DOI: https://doi.org/10.1016/j.carbon.2021.03.020

This paper is behind a paywall.

Sunlight makes transparent wood even lighter and stronger

Researchers at the University of Maryland (US) have found a way to make their wood transparent by using sunlight. From a February 2, 2021 news article by Bob Yirka on phys.org (Note: Links have been removed),

A team of researchers at the University of Maryland, has found a new way to make wood transparent. In their paper published in the journal Science Advances, the group describes their process and why they believe it is better than the old process.

The conventional method for making wood transparent involves using chemicals to remove the lignin—a process that takes a long time, produces a lot of liquid waste and results in weaker wood. In this new effort, the researchers have found a way to make wood transparent without having to remove the lignin.

The process involved changing the lignin rather than removing it. The researchers removed lignin molecules that are involved in producing wood color. First, they applied hydrogen peroxide to the wood surface and then exposed the treated wood to UV light (or natural sunlight). The wood was then soaked in ethanol to further clean it. Next, they filled in the pores with clear epoxy to make the wood smooth.

Caption: Solar-assisted large-scale fabrication of transparent wood. (A) Schematic showing the potential large-scale fabrication of transparent wood based on the rotary wood cutting method and the solar-assisted chemical brushing process. (B) The outdoor fabrication of lignin-modified wood with a length of 1 m [9 August 2019 (the summer months) at 13:00 p.m. (solar noon), the Global Solar UV Index (UVI): 7 to 8]. (C) Digital photo of a piece of large transparent wood (400 mm by 110 mm by 1 mm). (D) The energy consumption, chemical cost, and waste emission for the solar-assisted chemical brushing process and NaClO2 solution–based delignification process. (E) A radar plot showing a comparison of the fabrication process for transparent wood. Photo credit: Qinqin Xia, University of Maryland, College Park. [downloaded from https://advances.sciencemag.org/content/7/5/eabd7342]

Bob McDonald in a February 5, 2021 posting on his Canadian Broadcasting Corporation (CBC) Quirks & Quarks blog provides a more detailed description of the new ‘solar-based transparency process’,

Early attempts to make transparent wood involved removing the lignin, but this involved hazardous chemicals, high temperatures and a lot of time, making the product expensive and somewhat brittle. The new technique is so cheap and easy it could literally be done in a backyard.

Starting with planks of wood a metre long and one millimetre thick, the scientists simply brushed on a solution of hydrogen peroxide using an ordinary paint brush. When left in the sun, or under a UV lamp for an hour or so, the peroxide bleached out the brown chromophores but left the lignin intact, so the wood turned white.

Next, they infused the wood with a tough transparent epoxy designed for marine use, which filled in the spaces and pores in the wood and then hardened. This made the white wood transparent.

As window material, it would be much more resistant to accidental breakage. The clear wood is lighter than glass, with better insulating properties, which is important because windows are a major source of heat loss in buildings. It also might take less energy to manufacture clear wood because there are no high temperatures involved.

Many different types of wood, from balsa to oak, can be made transparent, and it doesn’t matter if it is cut along the grain or against it. If the transparent wood is made a little thicker, it would be strong enough to become part of the structure of a building, so there could be entire transparent wooden walls.

Adele Peters in her February 2, 2021 article for Fast Company describes the work in Maryland and includes some information about other innovative and possibly sustainable uses of wood (Note: Links have been removed),

It’s [transparent wood] just one of a number of ways scientists and engineers are rethinking how we can use this renewable resource in construction. Skyscrapers made entirely out of wood are gaining popularity in cities around the world. And scientists recently discovered a technique to grow wood in a lab, opening up the possibility of using wood without having to chop down a forest.

There were three previous posts here about this work at the University of Maryland,

University of Maryland looks into transparent wood May 11, 2016 posting

Transparent wood more efficient than glass in windows? Sept, 8, 2016 posting

Glass-like wood windows protect against UV rays and insulate heat October 21, 2020 posting

I have this posting, which is also from 2016 but features work in Sweden,

Transparent wood instead of glass for window panes? April 1, 2016 posting

Getting back to the latest work from the University of Maryland, here’s a link to and a citation for the paper,

Solar-assisted fabrication of large-scale, patternable transparent wood by Qinqin Xia, Chaoji Chen, Tian Li, Shuaiming He, Jinlong Gao, Xizheng Wang and Liangbing Hu. Science Advances Vol. 7, no. 5, eabd7342 DOI: 10.1126/sciadv.abd7342 Published: 27 Jan 2021

This paper is open access.

One last item, Liangbing Hu has founded a company InventWood for commercializing the work he and his colleagues have done at the University of Maryland.

Lobster-inspired 3D printed concrete

A January 19, 2021 news item on ScienceDaily highlights bioinspired 3D printing of concrete,

New research shows that patterns inspired by lobster shells can make 3D printed concrete stronger, to support more complex and creative architectural structures.

Digital manufacturing technologies like 3D concrete printing (3DCP) have immense potential to save time, effort and material in construction.

They also promise to push the boundaries of architectural innovation, yet technical challenges remain in making 3D printed concrete strong enough for use in more free-form structures.

In a new experimental study, researchers at RMIT University [Australia] looked to the natural strength of lobster shells to design special 3D printing patterns.

Their bio-mimicking spiral patterns improved the overall durability of the 3D printed concrete, as well as enabling the strength to be precisely directed for structural support where needed.

Video: Carelle Mulawa-Richards

A January 19, 2021 RMIT University press release (also on EurekAlert) by Gosia Kaszubska, which originated the news item, goes into technical detail about the research once you get past the ‘fluffy’ bits,

When the team combined the twisting patterns with a specialised concrete mix enhanced with steel fibres, the resulting material was stronger than traditionally-made concrete.

Lead researcher Dr Jonathan Tran said 3D printing and additive manufacturing opened up opportunities in construction for boosting both efficiency and creativity.

“3D concrete printing technology has real potential to revolutionise the construction industry, and our aim is to bring that transformation closer,” said Tran, a senior lecturer in structured materials and design at RMIT.

“Our study explores how different printing patterns affect the structural integrity of 3D printed concrete, and for the first time reveals the benefits of a bio-inspired approach in 3DCP.

“We know that natural materials like lobster exoskeletons?have evolved into high-performance structures over millions of years, so by mimicking their key advantages we can follow where nature has already innovated.”

3D printing for construction

The automation of concrete construction is set to transform how we build, with construction the next frontier in the automation and data-driven revolution known as industry 4.0.

A 3D concrete printer builds houses or makes structural components by depositing the material layer-by-layer, unlike the traditional approach of casting concrete in a mould.

With the latest technology, a house can be 3D printed in just 24 hours for about half the cost, while construction on the world’s first 3D printed community began in 2019 in Mexico.

The emerging industry is already supporting architectural and engineering innovation, such as a 3D printed office building in Dubai, a nature-mimicking concrete bridge in Madrid and The Netherlands’ sail-shaped “Europe Building”.

The research team in RMIT’s School of Engineering focuses on 3D printing concrete, exploring ways to enhance the finished product through different combinations of printing pattern design, material choices, modelling, design optimisation and reinforcement options.

Patterns for printing

The most conventional pattern used in 3D printing is unidirectional, where layers are laid down on top of each other in parallel lines.

The new study published in a special issue of 3D Printing and Additive Manufacturing investigated the effect of different printing patterns on the strength of steel fibre-enhanced concrete.

Previous research by the RMIT team found that including 1-2% steel fibres in the concrete mix reduces defects and porosity, increasing strength. The fibres also help the concrete harden early without deformation, enabling higher structures to be built.

The team tested the impact of printing the concrete in helicoidal patterns (inspired by the internal structure of lobster shells), cross-ply and quasi-isotropic patterns (similar to those used for laminated composite structures and layer-by-layer deposited composites) and standard unidirectional patterns.

Supporting complex structures

The results showed strength improvement from each of the patterns, compared with unidirectional printing, but Tran said the spiral patterns hold the most promise for supporting complex 3D printed concrete structures.

“As lobster shells are naturally strong and naturally curved, we know this could help us deliver stronger concrete shapes like arches and flowing or twisted structures,” he said.

“This work is in early stages so we need further research to test how the concrete performs on a wider range of parameters, but our initial experimental results show we are on the right track.”

Further studies will be supported through a new large-scale mobile concrete 3D printer recently acquired by RMIT – making it the first research institution in the southern hemisphere to commission a machine of this kind.

The 5×5m robotic printer will be used by the team to research the 3D printing of houses, buildings and large structural components.

The team will also use the machine to explore the potential for 3D printing with concrete made with recycled waste materials such as soft plastic aggregate.

The work is connected to a new project with industry partners Replas and SR Engineering, focusing on sound-dampening walls made from post-consumer recycled soft plastics and concrete, which was recently supported with an Australian Government Innovations Connections grant.

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

Influences of Printing Pattern on Mechanical Performance of Three-Dimensional-Printed Fiber-Reinforced Concrete by Luong Pham, Guoxing Lu, and Phuong Tran. 3D Printing and Additive Manufacturing DOI: https://doi.org/10.1089/3dp.2020.0172 Published Online:30 Dec 2020

This paper is open access.

Fungal wearable tech and building materials

This is the first time I’ve seen wearable tech based on biological material, in this case, fungi. In diving further into this material (wordplay intended), I discovered some previous work on using fungi for building materials, which you’ll find later in this posting.

Wearable tech and more

A January 18, 2021 news item on phys.org provides some illumination on the matter,

Fungi are among the world’s oldest and most tenacious organisms. They are now showing great promise to become one of the most useful materials for producing textiles, gadgets and other construction materials. The joint research venture undertaken by the University of the West of England, Bristol, the U.K. (UWE Bristol) and collaborators from Mogu S.r.l., Italy, Istituto Italiano di Tecnologia, Torino, Italy and the Faculty of Computer Science, Multimedia and Telecommunications of the Universitat Oberta de Catalunya (UOC) has demonstrated that fungi possess incredible properties that allow them to sense and process a range of external stimuli, such as light, stretching, temperature, the presence of chemical substances and even electrical signals. [emphasis mine]

This could help pave the way for the emergence of new fungal materials with a host of interesting traits, including sustainability, durability, repairability and adaptability. Through exploring the potential of fungi as components in wearable devices, the study has verified the possibility of using these biomaterials as efficient sensors with endless possible applications.

A January 18, 2021 Universitat Oberta de Catalunya (UOC) press release (also on EurekAlert), which originated the news item, describes this vision for future wearable tech based on fungi,

Fungi to make smart wearables even smarter

People are unlikely to think of fungi as a suitable material for producing gadgets, especially smart devices such as pedometers or mobile phones. Wearable devices require sophisticated circuits that connect to sensors and have at least some computing power, which is accomplished through complex procedures and special materials. This, roughly speaking, is what makes them “smart”. The collaboration of Prof. Andrew Adamatzky and Dr. Anna Nikolaidou from UWE Bristol’s Unconventional Computing Laboratory, Antoni Gandia, Chief Technology Officer at Mogu S.r.l., Prof. Alessandro Chiolerio from Istituto Italiano di Tecnologia, Torino, Italy and Dr. Mohammad Mahdi Dehshibi, researcher with the UOC’s Scene Understanding and Artificial Intelligence Lab (SUNAI) have demonstrated that fungi can be added to the list of these materials.

Indeed, the recent study, entitled “Reactive fungal wearable” and featured in Biosystems, analyses the ability of oyster fungus Pleurotus ostreatus to sense environmental stimuli that could come, for example, from the human body. In order to test the fungus’s response capabilities as a biomaterial, the study analyses and describes its role as a biosensor with the ability to discern between chemical, mechanical and electrical stimuli.

“Fungi make up the largest, most widely distributed and oldest group of living organisms on the planet,” said Dehshibi, who added, “They grow extremely fast and bind to the substrate you combine them with”. According to the UOC researcher, fungi are even able to process information in a way that resembles computers.

“We can reprogramme a geometry and graph-theoretical structure of the mycelium networks and then use the fungi’s electrical activity to realize computing circuits,” said Dehshibi, adding that, “Fungi do not only respond to stimuli and trigger signals accordingly, but also allow us to manipulate them to carry out computational tasks, in other words, to process information”. As a result, the possibility of creating real computer components with fungal material is no longer pure science fiction. In fact, these components would be capable of capturing and reacting to external signals in a way that has never been seen before.

Why use fungi?

These fungi have less to do with diseases and other issues caused by their kin when grown indoors. What’s more, according to Dehshibi, mycelium-based products are already used commercially in construction. He said: “You can mould them into different shapes like you would with cement, but to develop a geometric space you only need between five days and two weeks. They also have a small ecological footprint. In fact, given that they feed on waste to grow, they can be considered environmentally friendly”.

The world is no stranger to so-called “fungal architectures” [emphasis mine], built using biomaterials made from fungi. Existing strategies in this field involve growing the organism into the desired shape using small modules such as bricks, blocks or sheets. These are then dried to kill off the organism, leaving behind a sustainable and odourless compound.

But this can be taken one step further, said the expert, if the mycelia are kept alive and integrated into nanoparticles and polymers to develop electronic components. He said: “This computer substrate is grown in a textile mould to give it shape and provide additional structure. Over the last decade, Professor Adamatzky has produced several prototypes of sensing and computing devices using the slime mould Physarum polycephalum, including various computational geometry processors and hybrid electronic devices.”

The upcoming stretch

Although Professor Adamatzky found that this slime mould is a convenient substrate for unconventional computing, the fact that it is continuously changing prevents the manufacture of long-living devices, and slime mould computing devices are thus confined to experimental laboratory set-ups.

However, according to Dehshibi, thanks to their development and behaviour, basidiomycetes are more readily available, less susceptible to infections, larger in size and more convenient to manipulate than slime mould. In addition, Pleurotus ostreatus, as verified in their most recent paper, can be easily experimented on outdoors, thus opening up the possibility for new applications. This makes fungi an ideal target for the creation of future living computer devices.

The UOC researcher said: “In my opinion, we still have to address two major challenges. The first consists in really implementing [fungal system] computation with a purpose; in other words, computation that makes sense. The second would be to characterize the properties of the fungal substrates via Boolean mapping, in order to uncover the true computing potential of the mycelium networks.” To word it another way, although we know that there is potential for this type of application, we still have to figure out how far this potential goes and how we can tap into it for practical purposes.

We may not have to wait too long for the answers, though. The initial prototype developed by the team, which forms part of the study, will streamline the future design and construction of buildings with unique capabilities, thanks to their fungal biomaterials. The researcher said: “This innovative approach promotes the use of a living organism as a building material that is also fashioned to compute.” When the project wraps up in December 2022, the FUNGAR project will construct a large-scale fungal building in Denmark and Italy, as well as a smaller version on UWE Bristol’s Frenchay Campus.

Dehshibi said: “To date, only small modules such as bricks and sheets have been manufactured. However, NASA [US National Aeronautics Space Administration] is also interested in the idea and is looking for ways to build bases on the Moon and Mars to send inactive spores to other planets.” To conclude, he said: “Living inside a fungus may strike you as odd, but why is it so strange to think that we could live inside something living? It would mark a very interesting ecological shift that would allow us to do away with concrete, glass and wood. Just imagine schools, offices and hospitals that continuously grow, regenerate and die; it’s the pinnacle of sustainable life.”

For the Authors of the paper, the point of fungal computers is not to replace silicon chips. Fungal reactions are too slow for that. Rather, they think humans could use mycelium growing in an ecosystem as a “large-scale environmental sensor.” Fungal networks, they reason, are monitoring a large number of data streams as part of their everyday existence. If we could plug into mycelial networks and interpret the signals, they use to process information, we could learn more about what was happening in an ecosystem.

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

Reactive fungal wearable by Andrew Adamatzky, Anna Nikolaidou, Antoni Gandia, Alessandro Chiolerio, Mohammad Mahdi Dehshibi. Biosystems Volume 199, January 2021, 104304 DOI: https://doi.org/10.1016/j.biosystems.2020.104304

This paper is behind a paywall.

Fungal architecture and building materials

Here’s a video, which shows the work which inspired the fungal architecture that Dr. Dehshibi mentioned in the press release about wearable tech,

The video shows a 2014 Hy-Fi installation by The Living for MoMA (Museum of Modern Art) PS1 in New York City. Here’s more about HyFi and what it inspired from a January 15, 2021 article by Caleb Davies for the EU (European Union) Research and Innovation Magazine and republished on phys.org (Note: Links have been removed),

In the summer of 2014 a strange building began to take shape just outside MoMA PS1, a contemporary art centre in New York City. It looked like someone had started building an igloo and then got carried away, so that the ice-white bricks rose into huge towers. It was a captivating sight, but the truly impressive thing about this building was not so much its looks but the fact that it had been grown.

The installation, called Hy-Fi, was designed and created by The Living, an architectural design studio in New York. Each of the 10,000 bricks had been made by packing agricultural waste and mycelium, the fungus that makes mushrooms, into a mould and letting them grow into a solid mass.

This mushroom monument gave architectural researcher Phil Ayres an idea. “It was impressive,” said Ayres, who is based at the Centre for Information Technology and Architecture in Copenhagen, Denmark. But this project and others like it were using fungus as a component in buildings such as bricks without necessarily thinking about what new types of building we could make from fungi.

That’s why he and three colleagues have begun the FUNGAR project—to explore what kinds of new buildings we might construct out of mushrooms.

FUNGAR (Fungal Architectures) can be found here, Mogu can be found here, and The Living can be found here.

Nuclear power plants take a cue from Roman concrete

Every once in a while I delve into concrete, especially Roman concrete, and cement. The most recent of these postings (until now) was a June 3, 2016 post titled, Making better concrete by looking to nature for inspiration.

A January 8, 2021 Nagoya University press release (also on EurekAlert but published Jan. 13, 2021) describes how nuclear power plants could lead the way to an eco-friendly modern concrete as durable as that the ancient Romans developed,

A rare mineral that has allowed Roman concrete marine barriers to survive for more than 2,000 years has been found in the thick concrete walls of a decommissioned nuclear power plant in Japan. The formation of aluminous tobermorite increased the strength of the walls more than three times their design strength, Nagoya University researchers and colleagues report in the journal Materials and Design. The finding could help scientists develop stronger and more eco-friendly concrete.

“We found that cement hydrates and rock-forming minerals reacted in a way similar to what happens in Roman concrete, significantly increasing the strength of the nuclear plant walls,” says Nagoya University environmental engineer Ippei Maruyama.

Research has shown that Roman concrete used in the construction of marine barriers has managed to survive for more than two millennia because seawater dissolves volcanic ash in the mixture, leading to the formation of aluminous tobermorite. Since aluminous tobermorite is a crystal, it makes the concrete more chemically stable and stronger. It is very difficult to incorporate aluminous tobermorite directly into modern-day concrete. Scientists have generated the mineral in the lab, but it requires very high temperatures above 70°C. On the other hand, laboratory experiments have shown that hot environments are detrimental to concrete strength, which has led to regulations that limit its use to temperatures below 65°C.

Maruyama and his colleagues found that aluminous tobermorite formed in a nuclear reactor’s concrete walls when temperatures of 40-55°C were maintained for 16.5 years.

The samples were taken from the Hamaoka Nuclear Power Plant in Japan, which operated from 1976 to 2009.

In-depth analyses showed that the reactor’s very thick walls were able to retain moisture. Minerals used to make the concrete reacted in the presence of this water, increasing availability of silicon and aluminium ions and the alkali content of the wall. This ultimately led to the formation of aluminous tobermorite.

“Our understanding of concrete is based on short-term experiments conducted at lab time scales,” says Maruyama. “But real concrete structures give us more insights for long-term use.”

Maruyama and his colleagues are searching for ways to make concrete more durable and environmentally friendly. Cement used in concrete manufacturing produces nearly 10% of human-made carbon dioxide emissions, so the team is looking to produce more eco-friendly mixtures that still meet standardized requirements for strong concrete structures.

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

Long-term use of modern Portland cement concrete: The impact of Al-tobermorite formation by Ippei Maruyama, Jiří Rymeš, Abudushalamu Aili, Shohei Sawada, Osamu Kontani, Shinya Ueda, Ryu Shimamoto. Materials & Design
Volume 198, 15 January 2021, 109297 DOI: https://doi.org/10.1016/j.matdes.2020.109297

This paper appears to be open access.

Glass-like wood windows protect against UV rays and insulate heat

Engineers at the University of Maryland designed a transparent ceiling made of wood that highlights the natural woodgrain pattern. Credit: A. James Clark School of Engineering, University of Maryland [downloaded from https://phys.org/news/2020-08-glass-like-wood-insulates-tough-blocks.html]

An August 7, 2020 news item by Martha Hell on phys.org announces the latest research (links to previous posts about this research at the end of this post) on ‘transparent’ wood from the University of Maryland,

Need light but want privacy? A new type of wood that’s transparent, tough, and beautiful could be the solution. This nature-inspired building material allows light to come through (at about 80%) to fill the room but the material itself is naturally hazy (93%), preventing others from seeing inside.

An August 16, 2020 University of Maryland news release (also on EurekAlert) describes the work in more detail,

Engineers at the A. James Clark School of Engineering at the University of Maryland (UMD) demonstrate in a new study that windows made of transparent wood could provide more even and consistent natural lighting and better energy efficiency than glass

In a paper just published [July 31, 20202] in the peer-reviewed journal Advanced Energy Materials [this seems to be an incorrectly cited journal; I believe it should be Nature Communications as indicated in the phys.org news item], the team, headed by Liangbing Hu of UMD’s Department of Materials Science and Engineering and the Energy Research Center lay out research showing that their transparent wood provides better thermal insulation and lets in nearly as much light as glass, while eliminating glare and providing uniform and consistent indoor lighting. The findings advance earlier published work on their development of transparent wood.

The transparent wood lets through just a little bit less light than glass, but a lot less heat, said Tian Li, the lead author of the new study. “It is very transparent, but still allows for a little bit of privacy because it is not completely see-through. We also learned that the channels in the wood transmit light with wavelengths around the range of the wavelengths of visible light, but that it blocks the wavelengths that carry mostly heat,” said Li.

The team’s findings were derived, in part, from tests on tiny model house with a transparent wood panel in the ceiling that the team built. The tests showed that the light was more evenly distributed around a space with a transparent wood roof than a glass roof.

The channels in the wood direct visible light straight through the material, but the cell structure that still remains bounces the light around just a little bit, a property called haze. This means the light does not shine directly into your eyes, making it more comfortable to look at. The team photographed the transparent wood’s cell structure in the University of Maryland’s Advanced Imaging and Microscopy (AIM) Lab.

Transparent wood still has all the cell structures that comprised the original piece of wood. The wood is cut against the grain, so that the channels that drew water and nutrients up from the roots lie along the shortest dimension of the window. The new transparent wood uses theses natural channels in wood to guide the sunlight through the wood.

As the sun passes over a house with glass windows, the angle at which light shines through the glass changes as the sun moves. With windows or panels made of transparent wood instead of glass, as the sun moves across the sky, the channels in the wood direct the sunlight in the same way every time.

“This means your cat would not have to get up out of its nice patch of sunlight every few minutes and move over,” Li said. “The sunlight would stay in the same place. Also, the room would be more equally lighted at all times.”

Working with transparent wood is similar to working with natural wood, the researchers said. However, their transparent wood is waterproof due to its polymer component. It also is much less breakable than glass because the cell structure inside resists shattering.

The research team has recently patented their process for making transparent wood. The process starts with bleaching from the wood all of the lignin, which is a component in the wood that makes it both brown and strong. The wood is then soaked in epoxy, which adds strength back in and also makes the wood clearer. The team has used tiny squares of linden wood about 2 cm x 2 cm, but the wood can be any size, the researchers said.

Here’s a link to and a citation for the July 31, 2020 paper,

Scalable aesthetic transparent wood for energy efficient buildings by Ruiyu Mi, Chaoji Chen, Tobias Keplinger, Yong Pei, Shuaiming He, Dapeng Liu, Jianguo Li, Jiaqi Dai, Emily Hitz, Bao Yang, Ingo Burgert & Liangbing Hu. Nature Communications volume 11, Article number: 3836 (2020) DOI: https://doi.org/10.1038/s41467-020-17513-w Published 31 July 2020

This paper is open access.

There were two previous posts about this work at the University of Maryland,

University of Maryland looks into transparent wood May 11, 2016 posting

Transparent wood more efficient than glass in windows? Sept, 8, 2016 posting

I also have this posting, which is also from 2016 but features work in Sweden,

Transparent wood instead of glass for window panes? April 1, 2016 posting

I seem to have stumbled across a number of transparent wood stories in 2016. Hmm I think I need to spend more time searching previous titles for my postings so I didn’t end up with too many that sound similar.

Colo(u)r-changing building surfaces thanks to gold nanoparticles

Gold, at the nanoscale, has different properties than it has at the macroscale and research at the University of Cambridge has found a new way to exploit gold’s unique properties at the nanoscale according to a May 13, 2019 news item item on ScienceDaily,

The smallest pixels yet created — a million times smaller than those in smartphones, made by trapping particles of light under tiny rocks of gold — could be used for new types of large-scale flexible displays, big enough to cover entire buildings.

The colour pixels, developed by a team of scientists led by the University of Cambridge, are compatible with roll-to-roll fabrication on flexible plastic films, dramatically reducing their production cost. The results are reported in the journal Science Advances [May 10, 2019].

A May 10,2019 University of Cambridge press release (also on EurekAlert), which originated the news item, delves further into the research,

It has been a long-held dream to mimic the colour-changing skin of octopus or squid, allowing people or objects to disappear into the natural background, but making large-area flexible display screens is still prohibitively expensive because they are constructed from highly precise multiple layers.

At the centre of the pixels developed by the Cambridge scientists is a tiny particle of gold a few billionths of a metre across. The grain sits on top of a reflective surface, trapping light in the gap in between. Surrounding each grain is a thin sticky coating which changes chemically when electrically switched, causing the pixel to change colour across the spectrum.

The team of scientists, from different disciplines including physics, chemistry and manufacturing, made the pixels by coating vats of golden grains with an active polymer called polyaniline and then spraying them onto flexible mirror-coated plastic, to dramatically drive down production cost.

The pixels are the smallest yet created, a million times smaller than typical smartphone pixels. They can be seen in bright sunlight and because they do not need constant power to keep their set colour, have an energy performance that makes large areas feasible and sustainable. “We started by washing them over aluminized food packets, but then found aerosol spraying is faster,” said co-lead author Hyeon-Ho Jeong from Cambridge’s Cavendish Laboratory.

“These are not the normal tools of nanotechnology, but this sort of radical approach is needed to make sustainable technologies feasible,” said Professor Jeremy J Baumberg of the NanoPhotonics Centre at Cambridge’s Cavendish Laboratory, who led the research. “The strange physics of light on the nanoscale allows it to be switched, even if less than a tenth of the film is coated with our active pixels. That’s because the apparent size of each pixel for light is many times larger than their physical area when using these resonant gold architectures.”

The pixels could enable a host of new application possibilities such as building-sized display screens, architecture which can switch off solar heat load, active camouflage clothing and coatings, as well as tiny indicators for coming internet-of-things devices.
The team are currently working at improving the colour range and are looking for partners to develop the technology further.

The research is funded as part of a UK Engineering and Physical Sciences Research Council (EPSRC) investment in the Cambridge NanoPhotonics Centre, as well as the European Research Council (ERC) and the China Scholarship Council.

This image accompanies the press release,

Caption: eNPoMs formed from gold nanoparticles (Au NPs) encapsulated in a conductive polymer shell. Credit: NanoPhotonics Cambridge/Hyeon-Ho Jeong, Jialong Peng Credit: NanoPhotonics Cambridge/Hyeon-Ho Jeong, Jialong Peng

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

Scalable electrochromic nanopixels using plasmonics by Jialong Peng, Hyeon-Ho Jeong, Qianqi Lin, Sean Cormier, Hsin-Ling Liang, Michael F. L. De Volder, Silvia Vignolini, and Jeremy J. Baumberg. Science Advances Vol. 5, no. 5, eaaw2205 DOI: 10.1126/sciadv.aaw2205 Published: 01 May 2019

This paper appears to be open access.

Periodic table of nanomaterials

This charming illustration is the only pictorial representation i’ve seen for Kyoto University’s (Japan) proposed periodic table of nanomaterials, (By the way, 2019 is UNESCO’s [United Nations Educational, Scientific and Cultural Organization] International Year of the Periodic Table of Elements, an event recognizing the table’s 150th anniversary. See my January 8, 2019 posting for information about more events.)

Caption: Molecules interact and align with each other as they self-assemble. This new simulation enables to find what molecules best interact with each other to build nanomaterials, such as materials that work as a nano electrical wire.
Credit Illustration by Izumi Mindy Takamiya

A July 23, 2018 news item on Nanowerk announces the new periodic table (Note: A link has been removed),

The approach was developed by Daniel Packwood of Kyoto University’s Institute for Integrated Cell-Material Sciences (iCeMS) and Taro Hitosugi of the Tokyo Institute of Technology (Nature Communications, “Materials informatics for self-assembly of functionalized organic precursors on metal surfaces”). It involves connecting the chemical properties of molecules with the nanostructures that form as a result of their interaction. A machine learning technique generates data that is then used to develop a diagram that categorizes different molecules according to the nano-sized shapes they form.

This approach could help materials scientists identify the appropriate molecules to use in order to synthesize target nanomaterials.

A July 23, 2018 Kyoto University press release on EurekAlert, which originated the news item, explains further about the computer simulations run by the scientists in pursuit of their specialized periodic table,

Fabricating nanomaterials using a bottom-up approach requires finding ‘precursor molecules’ that interact and align correctly with each other as they self-assemble. But it’s been a major challenge knowing how precursor molecules will interact and what shapes they will form.

Bottom-up fabrication of graphene nanoribbons is receiving much attention due to their potential use in electronics, tissue engineering, construction, and bio-imaging. One way to synthesise them is by using bianthracene precursor molecules that have bromine ‘functional’ groups attached to them. The bromine groups interact with a copper substrate to form nano-sized chains. When these chains are heated, they turn into graphene nanoribbons.

Packwood and Hitosugi tested their simulator using this method for building graphene nanoribbons.

Data was input into the model about the chemical properties of a variety of molecules that can be attached to bianthracene to ‘functionalize’ it and facilitate its interaction with copper. The data went through a series of processes that ultimately led to the formation of a ‘dendrogram’.

This showed that attaching hydrogen molecules to bianthracene led to the development of strong one-dimensional nano-chains. Fluorine, bromine, chlorine, amidogen, and vinyl functional groups led to the formation of moderately strong nano-chains. Trifluoromethyl and methyl functional groups led to the formation of weak one-dimensional islands of molecules, and hydroxide and aldehyde groups led to the formation of strong two-dimensional tile-shaped islands.

The information produced in the dendogram changed based on the temperature data provided. The above categories apply when the interactions are conducted at -73°C. The results changed with warmer temperatures. The researchers recommend applying the data at low temperatures where the effect of the functional groups’ chemical properties on nano-shapes are most clear.

The technique can be applied to other substrates and precursor molecules. The researchers describe their method as analogous to the periodic table of chemical elements, which groups atoms based on how they bond to each other. “However, in order to truly prove that the dendrograms or other informatics-based approaches can be as valuable to materials science as the periodic table, we must incorporate them in a real bottom-up nanomaterial fabrication experiment,” the researchers conclude in their study published in the journal xxx. “We are currently pursuing this direction in our laboratories.”

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

Materials informatics for self-assembly of functionalized organic precursors on metal surfaces by Daniel M. Packwood & Taro Hitosugi. Nature Communicationsvolume 9, Article number: 2469 (2018)DOI: https://doi.org/10.1038/s41467-018-04940-z Published 25 June 2018

This paper is open access.

Terahertz imagers at your fingertips

It seems to me that I stumbled across quite a few carbon nanotube (CNT) stories in 2018. This one comes courtesy of Japan (from a June 28, 2018 news item on Nanowerk),

Researchers at Tokyo Tech have developed flexible terahertz imagers based on chemically “tunable” carbon nanotube materials. The findings expand the scope of terahertz applications to include wrap-around, wearable technologies as well as large-area photonic devices.

Here’s a peek at an imager,

Figure 1. The CNT-based flexible THz imager (a) Resting on a fingertip, the CNT THz imager can easily wrap around curved surfaces. (b) Just by inserting and rotating a flexible THz imager attached to the fingertip, damage to a pipe was clearly detected. Courtesy Tokyo Tech

A June 28, 2018 Tokyo Tech Institute press release (also on Eurekalert), which originated the news item, provides more detail,

Carbon nanotubes (CNTs) are beginning to take the electronics world by storm, and now their use in terahertz (THz) technologies has taken a big step forward.

Due to their excellent conductivity and unique physical properties, CNTs are an attractive option for next-generation electronic devices. One of the most promising developments is their application in THz devices. Increasingly, THz imagers are emerging as a safe and viable alternative to conventional imaging systems across a wide range of applications, from airport security, food inspection and art authentication to medical and environmental sensing technologies.

The demand for THz detectors that can deliver real-time imaging for a broad range of industrial applications has spurred research into low-cost, flexible THz imaging systems. Yukio Kawano of the Laboratory for Future Interdisciplinary Research of Science and Technology, Tokyo Tech, is a world-renowned expert in this field. In 2016, for example, he announced the development of wearable terahertz technologies based on multiarrayed carbon nanotubes.

Kawano and his team have since been investigating THz detection performance for various types of CNT materials, in recognition of the fact that there is plenty of room for improvement to meet the needs of industrial-scale applications.

Now, they report the development of flexible THz imagers for CNT films that can be fine-tuned to maximize THz detector performance.

Publishing their findings in ACS Applied Nano Materials, the new THz imagers are based on chemically adjustable semiconducting CNT films.

By making use of a technology known as ionic liquid gating1, the researchers demonstrated that they could obtain a high degree of control over key factors related to THz detector performance for a CNT film with a thickness of 30 micrometers. This level of thickness was important to ensure that the imagers would maintain their free-standing shape and flexibility, as shown in Figure 1 [see above].

“Additionally,” the team says, “we developed gate-free Fermi-level2 tuning based on variable-concentration dopant solutions and fabricated a Fermi-level-tuned p-n junction3 CNT THz imager.” In experiments using this new type of imager, the researchers achieved successful visualization of a metal paper clip inside a standard envelope (see Figure 2.)

Non-contact, non-destructive visualization

Figure 2. Non-contact, non-destructive visualization

The CNT THz imager enabled clear, non-destructive visualization of a metal paper clip inside an envelope.

The bendability of the new THz imager and the possibility of even further fine-tuning will expand the range of CNT-based devices that could be developed in the near future.

Moreover, low-cost fabrication methods such as inkjet coating could make large-area THz imaging devices more readily available.

1 Ionic liquid gating

A technique used to modulate a material’s charge carrier properties.

2 Fermi level

A measure of the electrochemical potential for electrons, which is important for determining the electrical and thermal properties of solids. The term is named after the Italian–American physicist Enrico Fermi.

3 p-n junction

Refers to the interface between positive (p-type) and negative (n-type) semiconducting materials. These junctions form the basis of semiconductor electronic devices.

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

Fermi-Level-Controlled Semiconducting-Separated Carbon Nanotube Films for Flexible Terahertz Imagers by Daichi Suzuki, Yuki Ochiai, Yota Nakagawa, Yuki Kuwahara, Takeshi Saito, and Yukio Kawano. ACS Appl. Nano Mater., 2018, 1 (6), pp 2469–2475 DOI: 10.1021/acsanm.8b00421 Publication Date (Web): June 6, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.