Concrete is second only to water as the most widely used material in the world, and cement is the essential “manufactured” ingredient in concrete. More than 30 billion tons of concrete are used every year, and the demand for it continues to rise significantly with increases in infrastructure construction projects.
The primary ingredient in cement manufacturing is limestone, which when heated to about 900 degrees Celsius converts to calcium oxide, resulting in the release of carbon dioxide, or CO2. The calcium oxide is then heated up to as much as 1,500 degrees Celsius with silica and alumina sources to produce the binding component of cement known as cement clinker.
In addition to the CO2 released from limestone, the use of fossil fuels to provide the high heat for the chemical conversion of calcium oxide results in substantial CO2 emissions. In total, one ton of cement typically produces about 0.8 to 0.9 tons of CO2 emissions, resulting in approximately 8% of the world’s anthropogenic CO2 emissions, and about 25% of all industry carbon emissions.
“If cement manufacturing were ranked with individual countries based on their carbon impacts, the cement industry would be the third largest CO2 emitter overall in the world after China and the United States,” says Narayanan Neithalath, the Fulton Professor of Structural Materials in the School of Sustainable Engineering and the Built Environment, part of the Ira A. Fulton Schools of Engineering at Arizona State University.
Through a National Science Foundation Future Manufacturing Research Grant, Neithalath and his research team are exploring new techniques for manufacturing cement to reduce carbon emissions through a synergy of novel energy sources and alterations in the processes and ingredients used.
“If we stand a reasonable chance of staying below the two degrees Celsius warming target set by the Paris Agreement, cement-related emissions will have to fall by more than 20% in the coming decade, after accounting for about a 20% increase in cement production and consumption to meet the demands of economic development and urbanization in many parts of the world,” Neithalath says.
Team of experts taking on big challenge
Cement manufacturing has come to be known as a particularly hard-to-decarbonize operation, largely because of CO2 emissions produced by the standard chemical process used by industry. Standing in the way of a solution is the lack of economical and scalable options to provide the high temperatures needed to produce the necessary chemical reactions required for the production process.
“Construction is a big contributor to climate change,” Neithalath says. “There is no other material that can do all that concrete can, and since the demand for the product is not going to change and the construction industry is very comfortable with Portland cement, we must look carefully at alternate processing options for cement, to control the carbon emissions.”
Portland cement is the type of cement most commonly used as a basic ingredient of concrete, as well as mortar, stucco and some types of grout.
Cement companies have done well over the past several decades to ensure their production plants are energy efficient, Neithalath says. But regardless of the energy source used, the carbon dioxide produced from calcium carbonate still has to go somewhere, he adds.
“Several research projects around the world are looking at multiple solutions to this vexing problem,” he says. “There is no one lever to reducing concrete’s carbon emissions, but there is a general consensus that process changes in cement manufacturing could have the highest impact, though that could be the hardest thing to do.”
The NSF Future Manufacturing Research Grant project brings together ASU researchers with expertise in a variety of fields, including Patrick Phelan, a professor in the School for Engineering of Matter, Transport and Energy, part of the Fulton Schools; Dong-Kyun Seo, a professor in the School of Molecular Sciences; and Diana Bowman, the associate dean for applied research and engagement in the Sandra Day O’Connor College of Law at ASU.
Other partners include Aditya Kumar, an associate professor of materials science and engineering at Missouri University of Science and Technology, and Srinivas Kilambi, a chemical engineer and innovator.
Small changes can solve big problems
Professor Narayanan Neithalath’s work is contributing to the development of innovations to make concrete production eco-friendly, improve cement manufacturing and achieve advances in construction processes. Neithalath’s accomplishments to date have earned him the status of an American Concrete Institute Fellow. Photo by Bobbi Ramirez/ASU
To address these carbon emission challenges, Neithalath says the research will focus on two main goals. The first involves separating lime from the limestone without producing carbon dioxide through novel electrolytic and hybrid routes. The second involves cement synthesis through a low-energy pathway, utilizing autocatalysis, a process for which energy can be provided through renewable sources such as solar power.
The important questions Neithalath and his research team will address relate to the consistency of cement produced and the scalability of the production process.
“While this is likely feasible experimentally, these are relevant questions when it comes to large-scale production and industry adoption of what we can develop,” Neithalath says.
There is a need to enable significant advancements by industry without requiring complete replacement of existing manufacturing infrastructure, he says, because the costs and time necessary to do that quickly would put big strains on businesses.
Manufacturing and building industries also want to retain the comfort associated with the use of traditional cement and concrete, especially their unique properties and the capability to manufacture concrete in the large volumes needed to do infrastructure development at manageable costs, which ensures manufacturing companies their products will be the materials of choice for construction.
“The big challenge is not only about creating a new manufacturing process that is environmentally sustainable,” Neithalath says. “It is also about manufacturing concrete with the lowest carbon emissions possible without a big increase in the price. This is what we hope to accomplish.”
Monica Williams contributed to this article.
Science writer, Ira A. Fulton Schools of Engineering
A long-standing mystery in science is how the almost 100 billion individual neurons work together to form a network that forms the basis of who we are — every human thought, emotion and behavior.Mapping these constellations of cells and discovering their function has long been a goal of scores of 21st-century molecular cartographers working worldwide as part of the National Institutes of Health…
A long-standing mystery in science is how the almost 100 billion individual neurons work together to form a network that forms the basis of who we are — every human thought, emotion and behavior.
Mapping these constellations of cells and discovering their function has long been a goal of scores of 21st-century molecular cartographers working worldwide as part of the National Institutes of Health’s BRAIN Initiative Cell Census Network project. The overarching purpose of the atlas is to aid in the development of neuroscience research. The hope of the project is that it will allow scientists to gain a better understanding of brain diseases and hard-to-solve medical mysteries behind disorders such as autism and depression.
Now, a series of recently published studies has revealed the widespread profiles of the inner molecular workings of the brain at an unprecedented level and scale.
As part of the effort to better understand the evolution of the brains in people and animals, a research team led by scientists at Arizona State University, the University of Pennsylvania, the University of Washington and the Brotman Baty Institute generated the world’s largest primate brain-wide atlas.
“Mapping what cells are where and what they do in the adult primate brain is crucial both for understanding the evolution of human cognition and behavior as well as for identifying what happens when things go wrong and lead to neurological disorders,” said senior co-author Noah Snyder-Mackler, an associate professor at ASU’s School of Life Sciences and Center for Evolution and Medicine.
The researchers’ goal was to identify and examine many of the brain cells (neurons and non-neurons) and perform a complete molecular analysis using state-of-the-art single-cell technologies.
To do so, they used samples from 30 different brain regions to draw out and build up, cell by cell, a new atlas. Altogether, the final map was composed of a 4.2 million-cell atlas of the adult primate brain.
“Our data, which we have made open and available to the scientific community and broader public, represent the largest and most comprehensive multimodal molecular atlas in a primate to date, and are crucial for exploring how the many cells of the brain come together to give rise to the behavioral complexity of primates, including humans,” said senior co-author Jay Shendure, a professor of genome sciences at the University of Washington and director of the Brotman Baty Institute.
“These data will also provide a critical and much-needed map of complex human-relevant social behavior and disease, as well as the substrate for identifying similarities and differences in these cells and networks across species,” said senior co-author Michael Platt, a professor in the departments of neuroscience, psychology and marketing at the University of Pennsylvania.
For every cell nucleus, the scientists profiled gene expression (2.58 million transcriptomes) and a suite of complementary DNA gene regulatory regions (1.59 million epigenomes). Taken together, this type of “multi-omic” analysis allowed the authors to study the molecular blueprints that make up distinct brain cell types, thus providing an opportunity to study, and even manipulate, key cells in more detail.
From the gene expression profiles, they were able to identify hundreds of molecularly distinct brain cell types. They also found that cell composition differed extensively across the brain, revealing cellular signatures of region-specific functions — from the neurotransmitters involved in brain cell communication to support cells that help feed and protect the brain from diseases like Alzheimer’s.
They used their data to investigate a total of 53 phenotypes relevant to the risk of neurological diseases, disorders, syndromes, behaviors or other traits. Their results captured known roles of cell classes implicated in neurological diseases, including cells linked to cardioembolic stroke or ischemic stroke, the leading cause of neurological death in people.
They also found that genes linked to Alzheimer’s disease tended to fall within DNA regulatory regions that are only accessible in microglia — the brain’s primary immune cell that protects neurons — consistent with the prominent role of microglia proliferation and activation in Alzheimer’s disease found from genome-wide association studies (GWAS).
Many of the regulatory regions they identified were new, which allowed the team to explore the genetic architecture of neurological disease risk at the cellular level.
“We identified numerous associations between genetic risk for neurological disorders and the epigenomic states of specific cell types — some of which had yet to be connected,” said co-lead author Kenneth Chiou, postdoc in the Center for Evolution and Medicine and School of Life Sciences at ASU.
Another type of cell class, basket cells, were enriched for the greatest number of GWAS phenotypes, including disorders such as schizophrenia, bipolar disorder, major depressive disorder and, most strongly, epilepsy. They also found enrichment of Parkinson’s disease-associated sites among open regions in the glial OPC, oligodendrocyte and astrocyte cell classes.
Finally, they found that heritable sites associated with attention deficit/hyperactivity disorder (ADHD) in their analysis were enriched only among open regions of medium spiny neurons. Medium spiny neurons have been linked to behavioral hyperactivity and disrupted attention via activation of astrocyte-mediated synaptogenesis. Their results suggest that medium spiny neurons may be a promising new target for future ADHD-related study.
Together, “multi-omic” atlas now provides an open resource to the worldwide research community for further investigations into the evolution of the human brain and identifying novel targets for disease interventions.
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