Featured Research

from universities, journals, and other organizations

How Solid Is Concrete's Carbon Footprint?

Date:
May 24, 2009
Source:
National Science Foundation
Summary:
Many scientists currently think at least 5 percent of humanity's carbon footprint comes from the concrete industry, both from energy use and the carbon dioxide byproduct from the production of cement, one of concrete's principal components.

Concrete's carbon footprint is fairly large due to two factors: the energy used to heat limestone (CaCO3) in kilns to form CaO, one of the major components in concrete, and the large quantities of carbon dioxide released as the conversion of limestone to CaO proceeds. However, a recent study has shown that over time, five percent, or more, of the lost carbon dioxide reabsorbs back into the concrete, thereby reducing the ultimate carbon footprint.
Credit: Zina Deretsky, National Science Foundation

Many scientists currently think at least 5 percent of humanity's carbon footprint comes from the concrete industry, both from energy use and the carbon dioxide (CO2) byproduct from the production of cement, one of concrete's principal components.

Yet several studies have shown that small quantities of CO2 later reabsorb into concrete, even decades after it is emplaced, when elements of the material combine with CO2 to form calcite.

A study appearing in the June 2009 Journal of Environmental Engineering suggests that the re-absorption may extend to products beyond calcite, increasing the total CO2 removed from the atmosphere and lowering concrete's overall carbon footprint.

While preliminary, the research by civil and environmental engineering professor Liv Haselbach of Washington State University re-emphasizes findings first observed nearly half a century ago--that carbon-based chemical compounds may form in concrete in addition to the mineral calcite-now in the light of current efforts to stem global warming.

"Even though these chemical species may equate to only five percent of the CO2 byproduct from cement production, when summed globally they become significant," said Haselbach. "Concrete is the most-used building material in the world."

Researchers have known for decades that concrete absorbs CO2 to form calcite (calcium carbonate, CaCO3) during its lifetime, and even longer if the concrete is recycled into new construction--and because concrete is somewhat permeable, the effect extends beyond exposed surfaces.

While such changes can be a structural concern for concrete containing rebar, where the change in acidity can damage the metal over many decades, the CaCO3 is actually denser than some of the materials it replaces and can add strength.

Haselbach's careful analysis of concrete samples appears to show that other compounds, in addition to calcite, may be forming. Although the compounds remain unidentified, she is optimistic about their potential.

"Understanding the complex chemistry of carbon dioxide absorption in concrete may help us develop processes to accelerate the process in such materials as recycled concrete or pavement. Perhaps this could help us achieve a nearly net-zero carbon footprint, for the chemical reactions at least, over the lifecycle of such products."

That is the thrust of Haselbach's current NSF-funded work, where she is now looking at evaluating the lifecycle carbon footprint of many traditional and novel concrete applications, and looking for ways to improve them.

"This work is part of the portfolio of studies that NSF is funding in this vital area," added Bruce Hamilton, director of NSF's environmental sustainability program and a supporter of Haselbach's work. "Research relating to climate change is a priority."


Story Source:

The above story is based on materials provided by National Science Foundation. Note: Materials may be edited for content and length.


Cite This Page:

National Science Foundation. "How Solid Is Concrete's Carbon Footprint?." ScienceDaily. ScienceDaily, 24 May 2009. <www.sciencedaily.com/releases/2009/05/090518121000.htm>.
National Science Foundation. (2009, May 24). How Solid Is Concrete's Carbon Footprint?. ScienceDaily. Retrieved September 1, 2014 from www.sciencedaily.com/releases/2009/05/090518121000.htm
National Science Foundation. "How Solid Is Concrete's Carbon Footprint?." ScienceDaily. www.sciencedaily.com/releases/2009/05/090518121000.htm (accessed September 1, 2014).

Share This




More Matter & Energy News

Monday, September 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Australian Airlines Relax Phone Ban Too

Australian Airlines Relax Phone Ban Too

Reuters - Business Video Online (Aug. 26, 2014) Qantas and Virgin say passengers can use their smartphones and tablets throughout flights after a regulator relaxed a ban on electronic devices during take-off and landing. As Hayley Platt reports the move comes as the two domestic rivals are expected to post annual net losses later this week. Video provided by Reuters
Powered by NewsLook.com
Hurricane Marie Brings Big Waves to California Coast

Hurricane Marie Brings Big Waves to California Coast

Reuters - US Online Video (Aug. 26, 2014) Huge waves generated by Hurricane Marie hit the Southern California coast. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Chinese Researchers Might Be Creating Supersonic Submarine

Chinese Researchers Might Be Creating Supersonic Submarine

Newsy (Aug. 26, 2014) Chinese researchers have expanded on Cold War-era tech and are closer to building a submarine that could reach the speed of sound. Video provided by Newsy
Powered by NewsLook.com
Breakingviews: India Coal Strained by Supreme Court Ruling

Breakingviews: India Coal Strained by Supreme Court Ruling

Reuters - Business Video Online (Aug. 26, 2014) An acute coal shortage is likely to be aggravated as India's supreme court declared government coal allocations illegal, says Breakingviews' Peter Thal Larsen. Video provided by Reuters
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins