Featured Research

from universities, journals, and other organizations

Long-Term Safety Of Concrete For Holding Nuclear Waste Is Focus Of MIT Study

April 27, 2000
Massachusetts Institute Of Technology
Small cylinders of cement rolling to and fro in a gently rocking bath are key to MIT work that could aid efforts to safely contain nuclear waste.

Small cylinders of cement rolling to and fro in a gently rocking bath are key to MIT work that could aid efforts to safely contain nuclear waste.

Related Articles

Temporary measures for storing such waste already employ cement, a material that binds together small particles to make concrete. Concrete, in turn, is used to encase steel containers holding the waste. For permanent storage, however, researchers would like to be able to predict how the concrete‹specifically, the cement that makes it strong -- will weather over hundreds of years.

Enter the MIT work. Engineers led by Franz-Josef Ulm, the Gilbert T. Winslow Career Development Associate Professor of civil and environmental engineering, have created a laboratory test that allows them to observe in one day what Nature takes 300 to wrought. This accelerates concrete aging three times over what other researchers have achieved.


For the first time, the team also subjected the weathered materials to pressures from all sides, a situation closer to what could be expected in real life when concrete containers are buried underground. Other teams have just considered uniaxial, or one-dimensional, loading conditions.

The triaxial tests resulted in new insights on what happens to concrete when it is weakened and put under stress. They "show the importance of 'Thinking 3D' when monitoring the durability performance of concrete in nuclear waste containment," write Professor Ulm and colleagues in a paper to be presented in May at a meeting of the American Society of Civil Engineers.

His coauthors are Franz H. Heukamp, a graduate student in the Department of Civil and Environmental Engineering (CEE), and Dr. John T. Germaine, a CEE principal research associate. Two other key members of the team are Dr. Marc Mainguy, a CEE postdoctoral associate, and Jennifer Burtz, a CEE junior working on the project through the Undergraduate Research Opportunities Program.

The team is currently merging the experimental results with a theoretical model of concrete leaching being developed by Dr. Mainguy. "Our goal is to go back to real-life structures, monitor the environment around them, and predict by model-based simulation what the concrete will do over extended periods of time," Professor Ulm said. And if a parameter changes‹say groundwater begins to seep around the structure‹"we'll be able to predict its eventual effect, and intervene in time to slow down or reverse the aging," Professor Ulm said.

The current lab test can comfortably predict aging up to about 300 years. Professor Ulm is confident that the work can be extrapolated to over 1,000 years. "When, and if, spent nuclear fuel from the US is buried in the Department of Energy proposed repository at Yucca Mountain, it will be placed in concrete casks that are supposed to maintain integrity at least 300 to 1,000 years," said Mujid Kazimi, an MIT professor of nuclear engineering who Professor Ulm has consulted about the work.


In a process akin to osteoporosis, concrete can weaken over time when water leaches calcium from the material. Just as in bones, the calcium is what gives concrete its strength.

"The challenge in studying this is that concrete aging is a very slow process," Mr. Heukamp said. "It could take a couple hundred years to really dissolve a concrete structure." However, this is the time scale over which the structural integrity of concrete applied in nuclear waste containment must be ensured.

To accelerate the process, the MIT researchers replaced the water with a highly concentrated solution of ammonium nitrate. The beauty of that solution: "The chemical process of calcium leaching is still the same, but it occurs at a much higher rate," Mr. Heukamp said. Coupled with an oscillating table developed by Dr. Germaine, which ensures an even concentration of solution around each sample, the MIT researchers had their setup for accelerated material aging by calcium leaching.

The next step: expose the weathered materials to stress. To do so, the team placed samples into a triaxial high-pressure cell that applied pressure from all sides. When they applied a shear, or slightly larger stress from one side, slivers of the material slipped apart, much like what happens to a high pile of books if you drop something on it from slightly off center.

This was the first time a team has studied the behavior of weathered concrete under triaxial stress. A key insight: the researchers found a significant loss of frictional performance in the artificially aged cement paste. The leached calcium left large pores that collapsed under the pressure, allowing the material to slip apart.

Professor Ulm noted that the microstructure of the leached cement paste, as visualized with an environmental scanning electron microscope, "showed a strong similarity to that of osteoporotic trabecular bones."

"So a material that is originally very strong ultimately ages to one that behaves like a weak low-friction soil, such as clay," he concluded.

The research was sponsored by the Nuclear Energy Research Initiative Program of the Department of Energy. Professor Ulm also notes a significant collaboration with the Commissariat ΰ l'Ιnergie Atomique in France through Dr. Jerome Sercombe.

Story Source:

The above story is based on materials provided by Massachusetts Institute Of Technology. Note: Materials may be edited for content and length.

Cite This Page:

Massachusetts Institute Of Technology. "Long-Term Safety Of Concrete For Holding Nuclear Waste Is Focus Of MIT Study." ScienceDaily. ScienceDaily, 27 April 2000. <www.sciencedaily.com/releases/2000/04/000427072507.htm>.
Massachusetts Institute Of Technology. (2000, April 27). Long-Term Safety Of Concrete For Holding Nuclear Waste Is Focus Of MIT Study. ScienceDaily. Retrieved February 28, 2015 from www.sciencedaily.com/releases/2000/04/000427072507.htm
Massachusetts Institute Of Technology. "Long-Term Safety Of Concrete For Holding Nuclear Waste Is Focus Of MIT Study." ScienceDaily. www.sciencedaily.com/releases/2000/04/000427072507.htm (accessed February 28, 2015).

Share This

More From ScienceDaily

More Matter & Energy News

Saturday, February 28, 2015

Featured Research

from universities, journals, and other organizations

Featured Videos

from AP, Reuters, AFP, and other news services

Elon Musk's Hyperloop Moves Forward

Elon Musk's Hyperloop Moves Forward

Buzz60 (Feb. 27, 2015) — Zipping around at 800-miles an hour is coming closer to reality in California. An entire town is being built around Elon Musk&apos;s Hyperloop concept and it wants you to stop in for a ride when it&apos;s ready. Brett Larson is on board. Video provided by Buzz60
Powered by NewsLook.com
Vibrating Bicycle Senses Traffic

Vibrating Bicycle Senses Traffic

Reuters - Innovations Video Online (Feb. 26, 2015) — Dutch scientists have developed a smart bicycle that uses sensors, wireless technology and video to warn riders of traffic dangers. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
In Japan, Robot Dogs Are for Life -- And Death

In Japan, Robot Dogs Are for Life -- And Death

AFP (Feb. 25, 2015) — Robot dogs are the perfect pet for some in Japan who go to repairmen-turned-vets when their pooch breaks down - while a full Buddhist funeral ceremony awaits those who don&apos;t make it. Duration: 02:40 Video provided by AFP
Powered by NewsLook.com
London Show Dissects History of Forensic Science

London Show Dissects History of Forensic Science

AFP (Feb. 25, 2015) — Forensic science, which has fascinated generations with its unravelling of gruesome crime mysteries, is being put under the microscope in an exhibition of real criminal investigations in London. Duration: 00:53 Video provided by AFP
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.


Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News


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