A new paper from researchers at MIT is discussed in Mashable India September 2021 issue, has suggested various strategies to reduce greenhouse emissions concrete usage.
Concrete is the second most material consumed by humans after water. The ever-increasing human desire for growth has led to us using more and more concrete to construct ever more structures, such as buildings, dams, bridges, and more.
Not only is the production of concrete contributing to global warming, 3 out of 4 main ingredients used in concrete production—water, sand, and gravel—are also precious natural resources. While the production of the other ingredient—cement—is just as destructive and requires mining limestone.
Over the past century, humans have used so much concrete that the combined mass of all concrete in the world far outweighs the mass of every plant life on the planet. By some estimates, concrete accounts for over 8% of global carbon emissions worldwide.
But, although concrete is a notorious emitter of greenhouses gases,
production of concrete is getting cleaner.
Despite being one of the most carbon-intensive industries in the world, the demand for concrete has been increasing year on year. David Perilli, London-based Web Editor, published an article titled “A short look at low carbon cement and concrete” in April 2020 Global Cement Magazine, featuring 15 concepts—some in the idea stage, some in use—for reducing the amount of carbon dioxide embodied in cement and concrete. The Bloomberg Businessweek Magazine December 2020 issue featured more ideas on the cutting edge, including solar-powered cement production.
15 CONCEPTS for reducing the amount
of carbon dioxide. Click to enlarge.
These are just a few of the ideas scientists and engineers are working on. Concrete is truly a building block of the modern world. It’s encouraging that there’s progress on making it less harmful to the environment:
GREEN IDEAS:
1—One of the coolest green ideas is to offset some of cement’s massive carbon dioxide emissions by putting carbon dioxide to good use in the production of concrete. It usually takes concrete a few weeks to reach maximum hardness, but injecting carbon dioxide speeds up the so-called curing process. The carbon dioxide becomes mineralized—and thus immobilized—by reacting with calcium ions in the cement. CO₂ Mineralization is described on the CarbonCure Website as: Once injected into the concrete mix, the CO₂ reacts with calcium ions from cement to form a nano-sized mineral, Calcium Carbonate, which becomes embedded in the concrete. This makes the concrete stronger, enabling mix optimization while eliminating the CO₂. Innovative “Carbon Cure” CO₂ Technology Website: CarbonCure injects a precise dosage of captured carbon dioxide (CO₂) into concrete, where the CO₂ becomes chemically converted into a mineral. A statement from a report by the National Academy of Sciences, Gaseous Carbon Waste Streams Utilization, stated in 2020: “Because these building materials are used at enormous scale and have product lifetimes that span decades, mineral carbonation represents a significant opportunity for long-term carbon sequestration in addition to being an opportunity for carbon utilization.“
2—Another green idea is to replace some of the cement in concrete with other “cementitious” materials. Not exactly a new idea, but the urgency of reducing the environmental impact of cement and concrete is driving companies to invent ways to use these materials more. Examples include:
• fly ash—a byproduct of coal combustion
• slag—a byproduct of steel production
3—A completely different approach to green cement featured in the December issue of Global Cement is being co-developed by Synhelion of Switzerland and Cemex of Mexico. The idea is to use mirrors to focus sunlight into a beam hot enough to sinter limestone and clay without any need for burning fuel.
IMPORTANT LINKS:
April 2020 Global Cement Magazine article / paper: www.globalcement.com/news/item/10667-a-short-look-at-low-carbon-cement-and-concrete
Businessweek Magazine December 2020 article: www.bloomberg.com/news/articles/2020-12-14/locking-carbon-dioxide-into-concrete-is-a-cool-idea.
CarbonCure website: www.carboncure.com/technology/
While countries around the world are looking for ways to curb their carbon footprints,
reducing the environmental impacts of concrete usage is critical.
New research in a paper titled “The role of concrete in life cycle greenhouse gas emissions of US buildings and pavements” from a team of scientists at MIT’s Concrete Sustainability Hub may finally have a solution. In a paper published in the journal Proceedings of the National Academy of Sciences, the researchers outline ways in which emissions from concrete could be minimized.
The paper suggests (Despite continuing increase in demand for concrete):
• An extensive life-cycle assessment of the construction industry
– to estimate how greenhouse gas emissions reduction strategies could minimize the total emissions annually
– find out how those reductions would compare to national greenhouse gas emission targets
• Reduction strategies could lead to a reduction of emissions between the years 2016 and 2050:
– from the pavement by up to 65%
using concrete can improve vehicle fuel efficiency
– from building construction by up to 57%
using concrete can endure natural disasters without needing energy and material-intensive repairs
• Concrete’s unique attributes can influence long-term sustainability and performance in the systems
PAPER:
The Massachusetts Institute of Technology (MIT) paper titled “The role of concrete in life cycle greenhouse gas emissions of US buildings and pavements” was a featured article in the e-News of “Proceedings of the National Academy of Sciences of the United States of America (PNAS)” website September 2021. The PAPER is BY:
Jeremy Gregory; Hessam AzariJafari; Ehsan Vahidi; Fengdi Guo; Franz-Josef Ulm; and Randolph Kirchain
1. aDepartment of Civil and Environmental Engineering-Massachusetts Institute of Technology (MIT), Cambridge, MA 02139;
2. bMaterials Research Laboratory-MIT, Cambridge, MA02139
Significance
Changes to concrete production as well as in building and pavements systems
—the largest consumers of concrete—
can lead to more than 50% reductions in associated GHG emissions by 2050
Over this period, the operational phase of newly constructed buildings and pavements still generates most GHG emissions unless the electrical grid, heating, and transportation are decarbonized aggressively. Meeting decarbonization targets will require lowering the GHG emissions of concrete production as well as innovative uses to lower building and vehicle fuel consumption. Owing to their low abatement costs, several concrete solutions should be prioritized in climate change policies. More than one-third of the embodied impacts of building and pavement construction can be offset by implementing concrete solutions.
Abstract
Concrete is a critical component of deep decarbonization efforts because of both the scale of the industry, and because of how its use impacts the building, transportation, and industrial sectors. We use a bottom-up model of current and future building and pavement stocks and construction in the United States to contextualize the role of concrete in greenhouse gas (GHG) reductions strategies under projected and ambitious scenarios, including embodied and use phases of the structures’ life cycle. We show that projected improvements in the building sector result in a reduction of 49% of GHG emissions in 2050 relative to 2016 levels, whereas ambitious improvements result in a 57% reduction in 2050, which is 22.5 Gt cumulative saving. The pavements sector shows a larger difference between the two scenarios with a 14% reduction of GHG emissions for projected improvements and a 65% reduction under the ambitious scenario, which is ∼1.35 Gt. This reduction occurs despite the fact that concrete usage in 2050 in the ambitious scenario is over three times that of the projected scenario because of the ways in which concrete lowers use phase emissions. Over 70% of future emissions from new construction are from the use phase.
For the “Proceedings of the National Academy of Sciences of the United States of America (PNAS)” article on the paper from Massachusetts Institute of Technology (MIT) Concrete Sustainability Hub (CSHub), to purchase the paper, to purchase the figures, and for more information, please go to: www.pnas.org/content/118/37/e2021936118
Article: https://in.mashable.com/science/24832/reducing-concretes-carbon-footprint-despite-growing-demand-is-viable
Paper titled “The role of concrete in life cycle greenhouse gas emissions of US buildings and pavements”: https://www.concretepavements.org/wp-admin/post.php?post=20542&action=edit
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