Tag Archives: graphene nanoplatelets

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.

Detecting COVID-19 in under five minutes with paper-based sensor made of graphene

A Dec. 7, 2020 news item on Nanowerk announced a new technology for rapid COVID-19 testing (Note: A link has been removed),

As the COVID-19 pandemic continues to spread across the world, testing remains a key strategy for tracking and containing the virus. Bioengineering graduate student, Maha Alafeef, has co-developed a rapid, ultrasensitive test using a paper-based electrochemical sensor that can detect the presence of the virus in less than five minutes.

The team led by professor Dipanjan Pan reported their findings in ACS Nano (“Rapid, Ultrasensitive, and Quantitative Detection of SARS-CoV-2 Using Antisense Oligonucleotides Directed Electrochemical Biosensor Chip”).

“Currently, we are experiencing a once-in-a-century life-changing event,” said Alafeef. “We are responding to this global need from a holistic approach by developing multidisciplinary tools for early detection and diagnosis and treatment for SARS-CoV-2.”

I wonder why they didn’t think to provide a caption for the graphene substrate (the square surface) underlying the gold electrode (the round thing) or provide a caption for the electrode. Maybe they assumed anyone knowledgeable about graphene would be able to identify it?

Caption: COVID-19 electrochemical sensing platform. Credit: University of Illinois

A Dec. 7, 2020 University of Illinois Grainger College of Engineering news release (also on EurekAlert) by Huan Song, which originated the news item, provides more technical detail including a description of the graphene substrate and the gold electrode, which make up the cheaper, faster COVID-19 sensing platform,

There are two broad categories of COVID-19 tests on the market. The first category uses reverse transcriptase real-time polymerase chain reaction (RT-PCR) and nucleic acid hybridization strategies to identify viral RNA. Current FDA [US Food and Drug Administration]-approved diagnostic tests use this technique. Some drawbacks include the amount of time it takes to complete the test, the need for specialized personnel and the availability of equipment and reagents.

The second category of tests focuses on the detection of antibodies. However, there could be a delay of a few days to a few weeks after a person has been exposed to the virus for them to produce detectable antibodies.

In recent years, researchers have had some success with creating point-of-care biosensors using 2D nanomaterials such as graphene to detect diseases. The main advantages of graphene-based biosensors are their sensitivity, low cost of production and rapid detection turnaround. “The discovery of graphene opened up a new era of sensor development due to its properties. Graphene exhibits unique mechanical and electrochemical properties that make it ideal for the development of sensitive electrochemical sensors,” said Alafeef. The team created a graphene-based electrochemical biosensor with an electrical read-out setup to selectively detect the presence of SARS-CoV-2 genetic material.

There are two components [emphasis mine] to this biosensor: a platform to measure an electrical read-out and probes to detect the presence of viral RNA. To create the platform, researchers first coated filter paper with a layer of graphene nanoplatelets to create a conductive film [emphasis mine]. Then, they placed a gold electrode with a predefined design on top of the graphene [emphasis mine] as a contact pad for electrical readout. Both gold and graphene have high sensitivity and conductivity which makes this platform ultrasensitive to detect changes in electrical signals.

Current RNA-based COVID-19 tests screen for the presence of the N-gene (nucleocapsid phosphoprotein) on the SARS-CoV-2 virus. In this research, the team designed antisense oligonucleotide (ASOs) probes to target two regions of the N-gene. Targeting two regions ensures the reliability of the senor in case one region undergoes gene mutation. Furthermore, gold nanoparticles (AuNP) are capped with these single-stranded nucleic acids (ssDNA), which represents an ultra-sensitive sensing probe for the SARS-CoV-2 RNA.

The researchers previously showed the sensitivity of the developed sensing probes in their earlier work published in ACS Nano. The hybridization of the viral RNA with these probes causes a change in the sensor electrical response. The AuNP caps accelerate the electron transfer and when broadcasted over the sensing platform, results in an increase in the output signal and indicates the presence of the virus.

The team tested the performance of this sensor by using COVID-19 positive and negative samples. The sensor showed a significant increase in the voltage of positive samples compared to the negative ones and confirmed the presence of viral genetic material in less than five minutes. Furthermore, the sensor was able to differentiate viral RNA loads in these samples. Viral load is an important quantitative indicator of the progress of infection and a challenge to measure using existing diagnostic methods.

This platform has far-reaching applications due to its portability and low cost. The sensor, when integrated with microcontrollers and LED screens or with a smartphone via Bluetooth or wifi, could be used at the point-of-care in a doctor’s office or even at home. Beyond COVID-19, the research team also foresees the system to be adaptable for the detection of many different diseases.

“The unlimited potential of bioengineering has always sparked my utmost interest with its innovative translational applications,” Alafeef said. “I am happy to see my research project has an impact on solving a real-world problem. Finally, I would like to thank my Ph.D. advisor professor Dipanjan Pan for his endless support, research scientist Dr. Parikshit Moitra, and research assistant Ketan Dighe for their help and contribution toward the success of this study.”

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

Rapid, Ultrasensitive, and Quantitative Detection of SARS-CoV-2 Using Antisense Oligonucleotides Directed Electrochemical Biosensor Chip by Maha Alafeef, Ketan Dighe, Parikshit Moitra, and Dipanjan Pan. ACS Nano 2020, 14, 12, 17028–17045 DOI: https://doi.org/10.1021/acsnano.0c06392 Publication Date:October 20, 2020 Copyright © 2020 American Chemical Society

I’m not sure where I found this notice but it is most definitely from the American Chemical Society: “This paper is freely accessible, at this time, for unrestricted RESEARCH re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the World Health Organization (WHO) declaration of COVID-19 as a global pandemic.”

Bicycle tyres, graphene, and a cycling revolution

Despite the wording in an Oct. 29, 2015 news item on Azonano you are not being invited to visit a factory (Note: A link has been removed),

Vittoria and Directa Plus host a unique opportunity to get an inside view in the factory where pristine Graphene is produced.

Not only will a select audience get a first-hand experience in seeing the blocking patent-protected end-to-end manufacturing process, they are exclusively selected to share the story of a material that is making it possible for Vittoria to lead a cycling revolution.

You are being invited to view this video,

An Oct. 26, 2015 Vittoria press announcement, which originated the news item, waxes eloquent about its graphene-producing partner, Directa Plus, and its new ‘graphene tyres’,

Directa Plus started its journey in 2005 [emphasis mine], in a time when a number of companies joined a race in blocking patents that would give them a huge head start in the market for recently isolated material Graphene.

With a philosophy of environmental neutrality, Directa Plus chose a unique clean direction that eventually gave them the edge in the bulk manufacturing of pristine Graphene nanoplatelets. At exactly the right time for both companies, the chairmen met each other at a function. When the application of Graphene became a logical next step, Vittoria offered the challenge to try and make this material work for cycling wheels and tires.

With continuous and significant investments, Vittoria is always seeking the cutting edge in cycling performance products through innovation. Through the Directa Plus-Vittoria partnership, both companies have unlocked a whole new level.

Unique Properties of Revolutionary Material Graphene

The guided tour immediately makes clear that the state of the art facilities of Directa Plus set the bar for next generation manufacturing. In a very white and clean environment, every step in the manufacturing process takes place in a very compact area and provide a different product with a dedicated purpose.

The company is extremely proud of the achievement to have zero impact on the environment. Both Vittoria and Directa Plus share an intense focus on quality, safety, health and environmental protection and this is clearly visible throughout the factory tour. After a close look at the overall production plant, the super-expansion process, the exfoliation and the output of 30 tons of Graphene end products in various shapes and forms, unique real-life applications are demonstrated.

One of the Graphene Plus’ products is a super-performant adsorbent towards hydrocarbons for water and soil purification. As demonstrated in the presence of the attendees, a highly polluted water tank is filtered with Graphene resulting in potable water.

Safety requirements prevent a live fireresistance demo, but Directa Plus shows a video that demonstrates the ability to treat a material with Graphene to achieve a completely non-flammable end result. Additional practical applications were illustrated through Vittoria best practices: commercial products, available for sale worldwide.

The Vittoria Best Practices: Carbon, Rubber, Special Applications

Vittoria introduced Graphene-enhanced carbon wheels for high performance road and MTB wheels in 2014. In close collaboration with Directa Plus, Vittoria will also soon introduce full carbon clinchers that can be mounted as a tubeless system.

In September this year, Vittoria announced a massive revision of its product range that includes the fastest road tire ever measured, as well as the best uncompromised competitive products for road racing in the market.

Furthermore, a highly innovative combination of Graphene and Vittoria’s 4C (4 compound) technology has enabled the introduction of more strength, more grip and greater durability for performance MTB tires. Vittoria even extended its newfound Graphene expertise to deliver fast-rolling and durable city tires that bring the greatly enhanced rubber properties to all consumers.

Perhaps the most remarkable achievement of all is the combined expertise of Directa Plus for
Graphene and the tire construction capabilities of Vittoria’s manufacturing facility Lion Tyres, dedicated to the special application of electric mountain bike tires. Again leveraging the 4C technology and specific Graphene-enhanced compounds, Vittoria has now developed 2 tires that can handle the electric engine torque as well as the roughest of terrains seemingly without effort.

No Compromise.

Effectively, the introduction of Graphene allows for natural material barriers of rubber to be removed, which means that there is no longer the need for compromises between speed, grip, durability and puncture resistance. All these features are now reaching their maximum possibilities.

Full carbon wheels will also reach new heights. With the application of Graphene, the natural properties of carbon are pushed way beyond natural limits in lateral stiffness, impact strength, weight reduction and heat dissipation, just to highlight a few key areas. The features of carbon are now extended to withstand the high pressure of tubeless mounted tires even under heavy braking circumstances without compromise.

In short, this is why Vittoria has started a cycling revolution.

Directa Plus started its graphene journey very early when you consider that the material was not successfully isolated until 2004 by Andre Geim and Konstantin (Kostya) Novosolov at the University of Manchester.