Modern theory from ancient impacts

Around 4 billion years ago, the solar system was far less hospitable than we find it now. Many of the large bodies we know and love were present, but probably looked considerably different, especially the Earth. We know from a range of sources, including ancient meteorites and planetary geology, that around this time there were vastly more collisions between, and impacts from, asteroids originating in the Mars-Jupiter asteroid belt.

Knowledge of these events is especially important to us, as the time period in question is not only when the surface of our planet was taking on a more recognizable form, but was also when life was just getting started. With more accurate details of Earth’s rocky history, it could help researchers answer some long-standing questions concerning the mechanisms responsible for life, as well as provide information for other areas of life science.

“Meteorites provide us with the earliest history of ourselves,” said Professor Yuji Sano from the Atmosphere and Ocean Research Institute at the University of Tokyo. “This is what fascinated me about them. By studying properties, such as radioactive decay products, of meteorites that fell to Earth, we can deduce when they came and where they came from. For this study we examined meteorites that came from Vesta, the second-largest asteroid after the dwarf planet Ceres.”

Sano and his team found evidence that Vesta was hit by multiple impacting bodies around 4.4 billion to 4.15 billion years ago. This is earlier than 3.9 billion years ago, which is when the late heavy bombardment (LHB) is thought to have occurred. Current evidence for the LHB comes from lunar rocks collected during the Apollo moon missions of the 1970s, as well as other sources. But these new studies are improving upon previous models and will pave the way for an up-to-date database of early solar impact records.

“That Vesta-origin meteorites clearly show us impacts earlier than the LHB raises the question, ‘Did the late heavy bombardment truly occur?'” said Sano. “It seems to us that early solar system impacts peaked sooner than the LHB and reduced smoothly with time. It may not have been the cataclysmic period of chaos that current models describe.”

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Demonstrating the dynamics of electron-light interaction originating from first principle

With the highest possible spatial resolution of less than a millionth of a millimetre, electron microscopes make it possible to study the properties of materials at the atomic level and thus demonstrate the realm of quantum mechanics. Quantum-physical fundamentals can be studied particularly well by the interactions between electrons and photons. Excited with laser light, for example, the energy, mass or velocity of the electrons changes. Professor Nahid Talebi from the Institute for Experimental and Applied Physics at Kiel University has invented a new toolbox to extend the theoretical description of electron-light interactions to the highest accurate level possible. She has combined Maxwell and Schrödinger equations in a time-dependent loop to fully simulate the interactions from first principles. Talebi’s simulation allows it for the first time to describe ultra-fast processes precisely in theory and to map them in real-time without using adiabatic approximation. Recently, she presented her results in the journal Physical Review Letters. In the long term, they could help to improve microscopy methods as Talebi is investigating in her ERC Starting Grant project “NanoBeam” funded by the European Research Council.

The ultrafast electron microscopy combines electron microscopy and laser technology. Having ultrafast electron pulses, the dynamics of the sample can be studied with femtosecond temporal resolutions. This also allows conclusions about the properties of the sample. Due to the further development of spectroscopy technology, it is now possible to study not only atomic and electronic structure of the samples but also their photonic excitations, such as plasmon polaritons.

For the first time the simulation depicts the process of the interactions as a film in real-time

However, the simulation of such electron-light-interactions is time-consuming and can only be carried out with high-performance computers. “Therefore, adiabatic approximations and one-dimensional electron models are often used, meaning that electron recoil and amplitude modulations have been neglected,” explains Nahid Talebi, Professor of Nanooptics at the Institute of Experimental and Applied Physics (IEAP) and an expert in simulations. For the first time, her new simulation shows the process of the electron-light interactions as a film in real-time, describing the complex interactions to the highest accurate level possible.

In her toolbox, she has combined Maxwell and Schroedinger equations in a time-dependent loop to fully simulate the interactions from first principles; therefore laying down the new field of electron-light interactions beyond adiabatic approximations. Due to this combination, Talebi was able to simulate what happens when an electron approaches a nanostructure of gold that was previously excited by a laser. Her simulation shows how the energy, momentum, and in general the shape of the wave packet of the electron change for each moment of the interaction. In this way, the full dynamics of the interaction caused by both single-photon and two-photon processes are captured. Single-photon processes are important for example to model electron energy-loss and -gain channels, whereas two-photon processes are responsible for modeling the laser-induced elastic channels such as the diffraction phenomenon.

Particularly in her simulation, Talebi observed a pronounced diffraction pattern that originates from strong interactions between electrons and photons based on the Kapitza-Dirac effect. This diffraction pattern can have promising applications in time-resolved holography, to unravel charge-carrier dynamics of solid-state and molecular systems.

Further improving spectroscopy methods with ERC project “NanoBeam”

“Our toolbox can be used to benchmark the many approximations in theoretical developments, including eikonal approximations, neglecting the recoil, and neglecting two-photon processes.” Talebi thinks. “Although we already have made a great step towards electron-light interactions beyond adiabatic approximations, there is still room for further developments.” Together with her team, she plans to include a three-dimensional Maxwell-Dirac simulation domain to model relativistic and spin interactions. She also wants to better understand the role of exchange and correlations during electron-electron interactions.

Another aim of Talebi is to utilize the insights from her theoretical modelling to propose novel methodologies for coherent control and shaping of the sample excitations using electron beams. With her project “NanoBeam” she intends to develop a novel spectral interferometry technique with the ability to retrieve and control the spectral phase in a scanning electron microscope to overcome the challenges in meeting both nanometers spatial and attosecond time resolution. The project is funded by an ERC grant from the European Research Council with about 1.5 million euros.

This study was funded by the European Union as part of the project “NanoBeam” as “ERC Starting Grant” of the European Research Council (ERC).

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Twitter Announces New API and Establishes API Development Roadmap

Less than a day removed from a security breach that led to several high profile Twitter accounts being hacked, Twitter is moving forward with the announcement of an all-new API. V2 of the Twitter API is intended to provide developers with a more robust feature set and a simplified path to advanced data access.

The API enhancements included in V2 are a result of direct feedback from developers via tweets, focus groups, and Twitter Developer labs. Developer Labs is a platform that allows developers to work with and provide feedback on Twitter’s latest technological developments. The new API focuses on adding the sort of flexibility and scalability that reflects the demands of Twitter’s diverse userbase. Twitter is adding new “elevated access options” and new “product tracks” in an attempt to provide tailored options that will appeal to a broad set of developers.

The Twitter API V2 represents a ground-up rebuild, with a focus on offering a combination of simplicity and a robust feature set. Specific new features mentioned in the announcement include: conversation threading, poll results in Tweets, pinned Tweets on profiles, spam filtering, and a more powerful stream filtering and search query language.

As for the platform’s new access options, Twitter is working to streamline top-to-bottom access to the platform via access leveling. Previously Twitter’s V1 APITrack this API offered tiers that provided more uniquely disparate experiences, leading to difficulty moving between tiers. The company hopes that unifying these experiences into one API experience will allow for a more seamless experience as the developer’s needs change. From now on all Developers regardless of their product track (more on this in a second) will have a path to advanced data access.

V2 introduces the idea of product tracks, tailored pathways designed to facilitate specific use cases. The new API will feature three separate pathways: Standard, Academic Research, and Business. Each pathway will have unique data access requirements while sharing a similar overall experience.

Additionally, Twitter is launching a new developer portal and establishing an API roadmap, both with the intention of allowing developers to more easily anticipate the APIs direction: 

“This is where you can get started with our new onboarding wizard, manage Apps, understand your API usage and limits, access our new support center, find documentation, and more to come in the future.”

Early access to the new API will become available next week and developers can request access via the developer portal. Although production-ready at that time, only some endpoints will be available immediately. The Academic Research and Business pathways will be released in the near future, while the Standard path will be open at release. 

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Author: <a href="">KevinSundstrom</a>


We believe we’re less likely than others are to fall for online scams

We believe we are less likely than others are to fall for phishing scams, thereby underestimating our own exposure to risk, a new cybersecurity study has found. The research also reports that this occurs, in part, because we overlook data, or “base rate information,” that could help us recognize risk when assessing our own behavior yet use it to predict that of others.

Together, the results suggest that those who are not informed of the risk that, for instance, work-from-home situations pose to online security may be more likely to jeopardize the safety of themselves and those they work for.

COVID-19 has had a devastating impact on the physical and mental health of people around the globe. Now, with so many more working online during the pandemic, the virus threatens to wreak havoc on the world’s “cyber health,” the researchers note.

“This study shows people ‘self-enhance’ when assessing risk, believing they are less likely than others to engage in actions that pose a threat to their cyber security — a perception that, in fact, may make us more susceptible to online attacks because it creates a false sense of security,” says Emily Balcetis, an associate professor in New York University’s Department of Psychology, who authored the study, which appears in the journal Comprehensive Results in Social Psychology.

“This effect is partially explained by differences in how we use base rate information, or actual data on how many people are actually victimized by such scams,” adds co-author Quanyan Zhu, a professor at NYU’s Tandon School of Engineering. “We avoid it when assessing our own behavior, but use it in making judgments about actions others might take. Because we’re less informed in assessing our actions, our vulnerability to phishing may be greater.”

Through March, more than two million U.S. federal employees had been directed to work from home — in addition to the millions working in the private sector and for state and local governments. This overhaul of working conditions has created significantly more vulnerabilities to criminal activity — a development recognized by the Department of Homeland Security. Its Cybersecurity and Infrastructure Security Agency issued an alert in March that foreshadowed the specific cyber vulnerabilities that arise when working from home rather than in the office.

In their study, the researchers sought to capture how people perceive their own vulnerabilities in relation to others’.

To do so, they conducted a series of experiments on computers screens in which subjects were shown emails that were phishing scams and were told these requests, which asked people to click links, update passwords, and download files, were illegitimate. To tempt the study’s subjects, college undergraduates, they were told complying with the requests would give them a chance to win an iPad in a raffle, allow them to have their access restored to an online account, or other outcomes they wanted or needed.

Half of the subjects were asked how likely they were to take the requested action while the other half was asked how likely another, specifically, “someone like them,” would do so.

On the screen that posed these questions, the researchers also provided the subjects with “base rate information”: The actual percentage of people at other large American universities who actually did the requested behavior (One, for instance, read: “37.3% of undergraduate students at a large American university clicked on a link to sign an illegal movie downloading pledge because they thought they must in order to register for classes”).

The researchers then deployed an innovative methodology to determine if the subjects used this “base rate information” in reporting the likelihood that they and “someone like them” would comply with the requested phishing action. Using eye-tracking technology, they could determine when the subjects actually read the provided information when reporting their own likelihood of falling for phishing attempts and when reporting the likelihood of others doing the same.

Overall, they found that the subjects thought they were less likely than are others to fall for phishing scams — evidence of “self-enhancement.” But the researchers also discovered that the subjects were less likely to rely on “base rate information” when answering the question about their own behavior yet more likely to use it when answering the question about how others would act.

“In a sense, they don’t think that base rate information is relevant to their own personal likelihood judgments, but they do think it’s useful for determining other people’s risk,” observes Balcetis.

“The patterns of social judgment we observed may be the result of individuals’ biased and motivated beliefs that they are uniquely able to regulate their risk and hold it at low or nonexistent levels,” Blair Cox, the lead researcher on the paper and scientist in NYU’s Department of Psychology, adds. “As a result, they may in fact be less likely to take steps to ensure their online safety.”

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3D Printing Industry

GKN Additive achieves 80% weight reduction with hydraulic block redesign

GKN Additive has 3D printed a hydraulic adapter block which was redesigned to weigh 80% less than its traditionally manufactured counterpart. The UK-based technology conglomerate employed Design for Additive Manufacturing (DfAM) principles to reduce material use, resulting in a lower weight and cost while also improving functionality. Traditionally manufactured hydraulic blocks Hydraulic blocks tend to […]

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Author: Kubi Sertoglu


Metal-organic frameworks can separate gases despite the presence of water

Metal-organic frameworks (MOFs) are promising materials for inexpensive and less energy-intensive gas separation even in the presence of impurities such as water.

Experimental analyses of the performance of metal-organic frameworks (MOFs) for the separation of propane and propene under real-world conditions revealed that the most commonly used theory to predict the selectivity does not yield accurate estimates, and also that water as an impurity does not have a detrimental effect on the material’s performance.

Short chain hydrocarbons are produced in mixtures after treatment of crude oil in refineries and need to be separated in order to be industrially useful. For example, propane is used as a fuel and propene as a raw material for chemical synthesis such as the production of polymers. However, the separation process usually requires high temperatures and pressures, and additionally the removal of other impurities such as water makes the process costly and energy-consuming.

The structure of the studied MOF offers a long-lived, adaptable, and most importantly efficient separation alternative at ambient conditions. They build on the fact that unsaturated molecules such as propene can be complexed with the material’s exposed metal atoms, while saturated ones such as propane fail to do so. While research has focused on developing different metal-organic frameworks for different separation processes, the feasibility of using these materials on industrial-scale applications is commonly only gauged by relying on a theory that makes many idealizing assumptions on both the material and the purity of the gasses. Thus, it has not been clear whether these predictions hold under more complicated but also more realistic conditions.

A team of Hokkaido University researchers around Professor Shin-ichiro Noro in collaboration with Professor Roland A. Fischer’s group at the Technical University of Munich conducted a series of measurements on the performance of a prototypical MOF to ascertain the material’s real-world selectivity, for both completely dry frameworks and ones pre-exposed to water.

Their results recently published in ACS Applied Materials & Interfaces show that the predicted selectivities of the material are too high compared to the real-world results. It also demonstrated that water does not drastically decrease the selectivity, although it does reduce the material’s capacity to adsorb gas. The team then performed quantum-chemical computations to understand why and realized that the water molecules themselves offer new binding sites to unsaturated hydrocarbons, such as propene (but not propane), thus retaining the material’s functionality.

The researchers state: “We showed the power of multi-component adsorption experiments to analyze the feasibility of using an MOF system.” They thus want to raise awareness of the shortcomings of commonly used theories and motivate other groups to also use a combination of different real-world measurements.

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Tone down your risk of skin cancer

Social media smarts could make you less susceptible to skin cancer as new research shows that media literacy skills can help change people’s attitudes about what is believed to be the ‘tanned ideal’.

Conducted by the University of South Australia, the research tested the ability of social media to influence people’s perceptions of tanning, finding that the greater an individual’s ability to critically access and evaluate social media posts, the less likely they were to idealise a golden tan.

The world-first study found that individuals with higher media literacy capabilities were much less likely to embrace or compare themselves to a tanned ideal, yet the opposite was true for those with fewer media literacy skills.

Lead researcher, UniSA’s Dr John Mingoia, says the findings highlight the importance of incorporating media literacy into sun safe education initiatives.

“The desire for tanned skin has long been part of Australian culture, yet despite everything we know about the dangers of tanning and the risk of skin cancer, people are still engaging in unsafe sun behaviour in the quest for what they consider a healthy golden glow,” Dr Mingoia says.

“In Australia, where we’re exposed to some of the highest levels of UV radiation in the world (and correspondingly, have one of the highest rates of skin cancer in the world), the desire for tanned skin is undeniably dangerous.

“The challenge is that people are exposed to images of the ‘tanned ideal’ on social media platforms — Instagram, Facebook, Snapchat and YouTube — where their perceptions of attractiveness are shaped and reinforced by images from advertisers, influencers, bloggers, and friends, many of which have been artificially enhanced or manipulated.

“It’s this kind of everyday organic content that we’re trying to combat, so that young adults can more easily identify the pervasive way that social media can influence their knowledge, attitudes and behaviours.

“Adding such media literacy skills to Australia’s existing and well-developed sun safe messages and campaigns will help individuals better manage their responses to media exposure, and importantly reduce any potentially negative self-comparisons.”

Skin cancer is the most common cancer worldwide, with 2-3 million non-melanoma skin cancers and 132,000 melanoma skin cancers occurring each year. In Australia, approximately, two in three Australian will be diagnosed with skin cancer by the time they are 70.

The study tested the responses of 151 young Australian adults (61 male and 90 females, aged 18-29) after exposure to a series of social media posts that featured either tanned or paler-skinned models. The most common skin type in the study was Fitzpatrick skin Type III (45 per cent) — people whose skin reacts to the sun by possibly freckling, burning on occasion, and sometimes tanning. Media literacy was assessed using the Media Attitudes Questionnaire (MAQ), a Likert-type ranking scale, that was adapted to test media literacy in relation to the tanned ideal.

The study showed that, on average, participants used social media for close to 173 minutes (three hours) a day, splitting their time between Facebook (96.7 per cent), YouTube (84.8 per cent), Instagram (69.5 per cent) and SnapChat (69.5 per cent).

Dr Mingoia says that social media presents additional barriers to healthy sun behaviours.

“Increasing people’s knowledge of how social media messages are constructed, manipulated and altered, as well as their capacity to impact cognition and attitudes, will improve awareness and scepticism of content on social media,” Dr Mingoia says.

“What we’re looking to do is add a complementary layer to existing sun safe education which we hope will lead to a reduced acceptance of what people see relating to tanned ideals on social media and consequently, better health outcomes.

“With more than 90 per cent of young adults regularly using social media, it’s a space we cannot afford to overlook in the battle to combat skin cancer.”

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Unreal Engine | GDC 2020

In less than two months, this year’s Game Developers Conference (GDC) will kick off in San Francisco, and with the next generation of consoles on their way, we couldn’t be more excited! 

GDC is one of our favorite times of the year, where we get the chance to catch you up on the State of Unreal in our keynote, and unveil all-new technology developments that will be coming your way down the road. It’s also a great opportunity to find out what talented teams around the world are doing to realize their creative ambitions and achieve success. And of course, our booth is the perfect venue for networking, socializing, and generally having a whole lot of fun.

Please save the date for the sessions below. 

Epic Games’ State of Unreal

Blue Shield of California Theater at YBCA, 700 Howard Street | Wednesday, March 18 | 11:00 AM – 12:00 PM 

Be a part of What’s Next! Join Epic Games and special guests as we reveal technological advancements that will open up a new generation of creative possibilities, freeing teams of all sizes to defy limits and redefine what they are able to achieve. Plus, get the latest news on Epic Online Services, the Epic Games Store, Epic MegaGrants, and more.GDC attendees with an Expo Pass Plus or higher are invited to attend. Can’t make it in person? Join our livestream at and get all the news as it happens.  

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Tech Talks

Blue Shield of California Theater at YBCA, 700 Howard Street | Wednesday, March 13

Getting ready for next-gen? There’s never been a better time to get an in-depth look into how Unreal Engine can help you create stunning games that will take advantage of everything the new hardware has to offer. Don’t miss our series of Tech Talks that will provide insights into today’s powerful toolset and a glimpse at what’s around the corner. 

Unreal Engine for Next-Gen Games 
12:30 PM  – 1:30 PM
Take a look at new and existing Unreal Engine features designed for next-gen game development.

The Future of Unreal Rendering 
2:15 PM  – 3:00 PM
Get a sneak peek at yet-to-be-released Unreal Engine rendering technology.

The Evolution of Real-Time VFX with Unreal Engine’s Niagara 
3:30 PM  – 4:30 PM
Join us for an in-depth look into the next phase of development and innovation.

Building Worlds in Fortnite with Unreal Engine 
5:00 PM  – 6:00 PM
Learn how the Fortnite team used Unreal Engine worldbuilding tools to create Chapter 2.Blog_Body_Image_5.jpg


Moscone Convention Center, 747 Howard Street
Wednesday, March 18 & Thursday, March 19 | 10:00 AM – 6:00 PM
Friday, March 20 | 10:00 AM – 3:00 PM

Unreal Engine booth, South 349

Visit our booth and be the first to see the latest cutting-edge Unreal Engine tech at our demo stations, and meet the devs behind the code to get your questions answered. Plus, our community team and evangelists will be there and would love to chat about how you can better tap into our resources and get involved in our user groups.

Want to get up to speed on topics like Sky and Atmosphere, Niagara VFX, Chaos Physics and Gameplay, Environment Building, and Quixel with some free training? Epic staff will be delivering rotating presentations for all three days of the expo in our Learning Theater.

Games. Jobs. Beer. South 327

Drop in at South 327, where you can check out dozens of awesome games and meet the developers behind them face-to-face, find plenty of tasty snacks and cold beer, and network for career opportunities. Blog_Body_Image_14.jpg

Additional sessions

Moscone Convention Center, 747 Howard Street

But wait, there’s more! If you’re in the process of—or thinking about—moving to Unreal Engine, you won’t want to miss our crash course. Plus, find out more about cross-play from our Epic Online Services team, and get answers to your burning questions and a glimpse of the road ahead for the Epic Games Store.

Epic Games Store: An Update and Q&A
Wednesday, March 18 | 3:30 PM – 4:30 PM | West Hall, Room 2020
Find out where the store is today, a year after launch, and learn what to expect in the future.

Crash Course for Studios New to Unreal Engine
Thursday, March 19 | 10:00 AM – 11:00 PM | West Hall, Room 3001
Moving to Unreal Engine? Learn the best practices and essential features for success.

Why Cross-Play Matters
Thursday, March 19 | 11:30 AM – 12:30 PM | West Hall, Room 2000
This panel session discusses the benefits and challenges of supporting cross-platform play, progression, and purchasing. 

Deconstructing Fortnite’s Cross-Platform Experience
Thursday, March 19  | 12:45 PM – 1:45 PM | West Hall, Room 2000
Hear what it takes to build and operate cross-play and cross-progression games.

Remember to bookmark our event page, which will be updated with more information in the coming weeks. We look forward to seeing you at GDC 2020!

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Using mountains for long-term energy storage

Batteries are rapidly becoming less expensive and might soon offer a cheap short-term solution to store energy for daily energy needs. However, the long-term storage capabilities of batteries, for example, in a yearly cycle, will not be economically viable. Although pumped-hydro storage (PHS) technologies are an economically feasible choice for long-term energy storage with large capacities — higher than 50 megawatts (MW) — it becomes expensive for locations where the demand for energy storage is often smaller than 20 MW with monthly or seasonal requirements, such as small islands and remote locations.

In a study published in the journal Energy, IIASA researcher Julian Hunt and his colleagues propose MGES to close the gap between existing short- and long-term storage technologies. MGES constitutes of building cranes on the edge of a steep mountain with enough reach to transport sand (or gravel) from a storage site located at the bottom to a storage site at the top. A motor/generator moves storage vessels filled with sand from the bottom to the top, similar to a ski lift. During this process, potential energy is stored. Electricity is generated by lowering sand from the upper storage site back to the bottom. If there are river streams on the mountain, the MGES system can be combined with hydropower, where the water would be used to fill the storage vessels in periods of high availability instead of the sand or gravel, thus generating energy. MGES systems have the benefit that the water could be added at any height of the system, thereby increasing the possibility of catching water from different heights in the mountain, which is not possible in conventional hydropower.

“One of the benefits of this system is that sand is cheap and, unlike water, it does not evaporate — so you never lose potential energy and it can be reused innumerable times. This makes it particularly interesting for dry regions,” notes Hunt. “Additionally, PHS plants are limited to a height difference of 1,200 meters, due to very high hydraulic pressures. MGES plants could have height differences of more than 5,000 meters. Regions with high mountains, for example, the Himalayas, Alps, and Rocky Mountains, could therefore become important long-term energy storage hubs. Other interesting locations for MGES are islands, such as Hawaii, Cape Verde, Madeira, and the Pacific Islands with steep mountainous terrain.”

In the paper, the authors propose a future energy matrix for the Molokai Island in Hawaii, using only wind, solar, batteries, and MGES to supply the island’s energy demand. Hunt emphasizes that the MGES technology should not be used for peak generation or storing energy in daily cycles — instead it fills a gap in the market for locations with long-term storage. MGES systems can, for instance, store energy continuously for months and then generate power continuously for months or when there is water available for hydropower, while batteries deal with the daily storage cycles.

“It is important to note that the MGES technology does not replace any current energy storage options but rather opens up new ways of storing energy and harnessing untapped hydropower potential in regions with high mountains,” Hunt concludes.

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New coal ash aggregate helps concrete cure

Coal ash is the less notorious byproduct of coal-fired power plants. It’s the residual solid waste that comes from burning coal. While it doesn’t have the same deleterious reputation of its airborne counterparts, tens of millions of tons of ash does up in landfills each year. Now researchers from Drexel University believe they have found a use for the powdery residue — one that could help make concrete more durable and crack-free.

Recently reported in the journal Cement and Concrete Composites, their discovery is a method for turning waste ash into a special concrete additive that helps to fortify its internal structure by promoting a uniform hardening process from the inside out. This additive — a high-performing, functional aggregate — could shorten the time it takes for concrete to harden and improve its durability by lowering the potential for crack formation, according to the researchers.

-Just the Right Mix-

Concrete is made from a mixture of fine powder and coarse rock particles, called aggregates, bonded by a mineral glue called a “cementing matrix,” made of cement and water. The aggregates form the strong internal structure of the concrete as the cementing matrix hardens to bind the ingredients together in a process called curing. For concrete to reach its maximum durability, the cement must mix thoroughly with water during the curing process so it all dries — and cures — at the same time.

“This is a very important part of the process because if the concrete dries too quickly during its curing, due to added water shortage, it can form cracks and other flaws. These drying shrinkage cracks cause the surface to be susceptible to aggressive fluid ingress creating concrete durability problems such as corrosion, salt damage, or freeze-thaw damage,” said Yaghoob Farnam, PhD, an assistant professor in Drexel’s College of Engineering and principle investigator of the research.

To ensure even curing there are a number of things concrete contractors might have to do, including constantly spraying the concrete, covering it with a membrane to keep it moist, submerging it in water or creating pools of water on its surface. All of these strategies consume time and resources and are complex enough that flaws could creep into the process. To help prevent this, in the last decade researchers have developed an internal curing concept that uses porous lightweight aggregate to aid the curing process. The aggregate can maintain a consistent level of moisture inside the concrete to help it cure evenly from the inside out.

“The use of a high-performance lightweight aggregate in concrete can be a solution to properly provide sufficient water reservoirs inside concrete as water is needed over time for curing cementitious matrix,” Farnam said.

-Working with Concrete is Hard-

Concrete is one of the most widely used building materials in the world. It’s the material of choice for most new high-volume roads, buildings, bridges and many other structures because of its durability and relative ease of application.

But one drawback to using concrete is that it requires just the right atmospheric conditions to allow proper mixing and even curing — not too hot, not too cold, not too dry.

Getting the exact amount of moisture inside concrete is difficult because the powder and aggregates form a tight cementing matrix that is difficult to penetrate once it begins drying. If the outside of the concrete dries out before the inside cures it can result in a weaker structure. As a result, contractors basically have one shot to get the ratio of liquid to solid just right, quickly and thoroughly mix it and pour the concrete before it starts drying.

“This is a common problem in concrete, so called ‘concrete drying,’ creates drying cracks and lower concrete strength and durability,” said Mohammad Balapour, a doctoral researcher in Farnam’s lab and lead author of the paper.

-Finding a Cure-

To give contractors more leeway in the process, Farnam’s team, in collaboration with faculty members in the Drexel’s Civil, Architectural, and Environmental Engineering Department, Grace Hsuan, PhD, and Sabrina Spatari, PhD, as well as E.J. Garboczi, PhD, from National Institute of Standards and Technology, looked at how functional lightweight aggregates can be developed from coal ash and used in concrete.

The concrete industry has limited access to natural or synthetic lightweight aggregates, according to Farnam, because of its dependency on limited sources of aggregate material. Farnam’s lab wanted to design an aggregate product that had optimal characteristics for mixing, strength and porousness — and find a way to make it out of an abundant waste material.

“The solution we came up with involved recycling this waste product, coal ash, into a porous, lightweight aggregate with excellent performance characteristics that could be produced at a lower cost than current natural and synthetic options,” Farnam said. “This material and process would not only benefit the concrete industry by improving the quality of their products, but it could also help keep coal ash out of landfills.”

The material they came up with is called “spherical porous reactive aggregate” — SPoRA, for short. It is made by combining the ash with chemicals that facilitate aggregate sintering and bonding, forming them into tiny spheres and then baking them at 1,160 degrees Celsius for a few minutes.

The end product is an aggregate pellet that can hold almost half its weight in water, which is better than traditional lightweight aggregates. And, as importantly, it can release that water at a regular rate from inside to the cementing matrix as it cures.

In the paper they report that two types of SPoRA perform better than some traditional lightweight aggregate materials — shale, clay and slate, and foamed glass — on measurements of shape, porousness, relative weight and ability to absorb and release water. These are all key metrics related to its ability to integrate with the cement mixture and release its moisture at the right time and in the right part of the structure as it forms.

“As the concrete begins to cure on the outside, the aggregate pellets are also releasing their moisture to help it cure from the inside out as well,” Balapour said. “This approach can help to maximize the durability of the concrete. And the SPoRA-making process is simple enough to produce aggregates of any size and water capacity, so we believe it could be used for a number of applications in the construction industry.”

Recycling a waste product like coal ash not only reduces the cost of making lightweight aggregate, but it also ensures that concrete producers will have access to it.

“Taking something that is a waste product — with mountains of it in landfills — and turning it into a useful product is an excellent example of how science can help to find sustainable solutions to society’s challenges,” Farnam said. “Not only does this help protect our natural environment but will also help to improve our built environment.”

The research was funded by the National Science Foundation.

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