corrosion

Self-healing concrete

June 25, 2025 By EarthWise Leave a Comment

Concrete is the most widely used building material on Earth. It has a dangerous and costly flaw: it cracks easily. Cracks in concrete can lead to inconvenient damage or to catastrophic structural failures such as collapses of buildings, bridges, or highways.

Concrete is made by mixing crushed stone and sand with powdered clay and limestone and adding water. The mixture hardens and once set becomes extremely strong. However, natural forces like freeze-thaw cycles, drying shrinkage, and heavy loads can cause cracks. Even very tiny cracks can allow liquids and gases to seep into embedded steel reinforcements causing corrosion and weakness.

For over 30 years, researchers have investigated microbe-mediated self-healing concrete. It involves introducing microbial healing agents into cracks and injecting nutrients for the healing agents to produce repair materials. It is not a very practical solution.

Researchers at Texas A&M University have developed a technique inspired by the behavior of lichen systems. Their system, like lichen, uses a combination of cyanobacteria which turns air and sunlight into food, and filamentous fungi, which produces minerals that seal the cracks.

In lab tests, the paired microbes were able to grow and produce crack-filling minerals even in challenging environments such as concrete. If it is possible to produce concrete that can heal itself, it would significantly reduce maintenance costs, extend its longevity, and even protect lives through increased safety.

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Cracking the Code: Deciphering How Concrete Can Heal Itself

Photo, posted May 21, 2009, courtesy of DesignMag via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Native plants and road salt pollution

February 12, 2025 By EarthWise Leave a Comment

Applying salt to roadways lowers the freezing point of water and prevents slippery surfaces, which makes it safer for people to drive in wintry conditions. In the U.S., more than 22 million tons of road salt is spread every year.

But road salt harms infrastructure and the environment. In fact, road salt damages cars and metal infrastructure by accelerating rust and corrosion. Road salt can also leach into soil and waterways, disrupting ecosystems, degrading soil, contaminating water, and damaging vegetation.

In cities and towns, road salts often wash into stormwater systems, posing health concerns and challenges for infrastructure.

A new study led by researchers from Virginia Tech looked at how salt affects plants and whether certain plants could mitigate salt pollution. The research team studied stormwater detention basins in Northern Virginia, examining the impacts of road salt on plants, soils, and water quality in green infrastructure systems.

The findings, which were recently published in the journal Science of the Total Environment, found that the amount of salt present in green infrastructure systems does reach levels that threaten plant communities. However, the researchers found that relying on salt-tolerant plants for mitigation is unlikely to be effective because they simply don’t take in enough salt.

Certain plants, particularly cattails, absorbed substantial amounts of salt. But even in a basin densely planted with salt-tolerant cattails, only up to 6% of the road salt applied during winter could be removed.

Plants alone cannot solve our salt pollution problem.

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Researcher studies the power of native plants to combat road salt pollution

Photo, posted January 22, 2025, courtesy of the City of Greenville, North Carolina via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

PFAS and groundwater

November 26, 2024 By EarthWise Leave a Comment

Per- and polyfluoroalkyl chemicals, more commonly known as PFAS, are a family of human-made chemicals that have been manufactured and used in a variety of industries since the 1940s. They provide water-resistance, oil-resistance, dirt-resistance, and corrosion-resistance to a wide range of products, including food wrappers and packaging, clothing, dental floss, nonstick cookware, textiles, and electronics.

Exposure to PFAS has been linked to birth defects, thyroid disease, liver disease, kidney disease, and cancer. These chemicals do not break down in the environment and therefore, over time, become concentrated in plants, animals, and people.

According to a new first-of-its kind study by scientists at the U.S. Geological Survey, more than 20% of the U.S. population could be drinking groundwater contaminated with PFAS. The study, which was recently published in the journal Science, found that those living in the Eastern U.S. are particularly likely to be exposed.

The study is the first to report national estimates of PFAS in untreated groundwater that supplies drinking water to private and public wells. The USGS research also provides the first estimate of the total number of Americans – anywhere from 71 to 95 million – who might be exposed to this contamination.

The researchers note that their estimates merely measure the existence of PFAS – before the water has undergone any treatment or filtering – meaning that, while they may be present, they may be at very low levels.

To find a link to the detailed USGS map showing the probability of PFAS groundwater contamination in your region, visit our website: EarthWiseRadio.org.

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PFAS in US Groundwater Interactive Dashboard

Predictions of groundwater PFAS occurrence at drinking water supply depths in the United States

Photo, posted January 12, 2008, courtesy of Andrew Kraker via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Enormous Cost Of Steel Corrosion | Earth Wise

February 28, 2023 By EarthWise Leave a Comment

Global steel production has been rising for decades. Because steel corrodes over time, part of the demand for more steel comes from the need to replace the steel used in construction materials – in everything from bridges to cars – that has become corroded over time. Studies have estimated that the economic cost of corrosion is an astonishing 3 to 4% of a nation’s gross domestic product. Globally, this means that steel corrosion costs the world trillions – yes, trillions with a T – of dollars each year.

On top of the staggering economic impact of corrosion, there is the fact that steel production is one of the largest greenhouse gas emitters of any industry, accounting for more than 25% of all manufacturing sector carbon emissions. In fact, steel manufacturing causes over 10% of total global carbon emissions.

As a result of regulations placed on the steel industry, technological advances in the steelmaking process have resulted in a 61% reduction in the industry’s energy consumption over the last 50 years. There are continuing efforts to reduce the energy consumption of steel making and to move away from the use of fossil fuels to produce the needed energy. But without significant improvements, just the emissions associated with replacing corroded steel could make the goals set by the Paris Climate Agreement unfeasible.

It’s hard to believe that something costing the world trillions of dollars and has a major negative impact on the climate is largely invisible. Steel corrosion is an enormous societal challenge that has gone under the radar for decades and therefore has not received anything like the attention it deserves.

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Reducing steel corrosion vital to combating climate change

Photo, posted July 24, 2008, courtesy of Phil Whitehouse via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Most Powerful Tidal Turbine Is Generating Power | Earth Wise

October 1, 2021 By EarthWise Leave a Comment

The movement of waves, tides, and currents in the ocean carry enormous amounts of energy that in principle could be harnessed and converted into electricity to help power our homes, buildings, and cities. Oceans cover nearly three-quarters of our planet, and the most populated areas of the world are located near oceans.

Ocean energy technologies lag far behind solar and wind power and remain mostly undeveloped. This is a result of the unique challenges standing in the way of widespread deployment. There are the considerable expenses of early-stage development, the wide variety of technical approaches from which winning strategies have yet to emerge, and the substantial challenges of operating in the ocean environment that include the physical impact of waves and tides, powerful and unpredictable weather, and corrosion and bio-fouling from the ocean and its inhabitants.

Despite these challenges, there is ongoing progress on ocean energy. The world’s most powerful tidal turbine has come online this past April. Known as the Orbital O2, the floating turbine is anchored in Scotland’s Fall of Warness, where a subsea cable connects it to the European Marine Energy Center.

The turbine produces enough electricity to meet the demand of about 2,000 homes in the UK. It is expected to operate for the next 15 years.

Built by the Scottish engineering company Orbital Marine, the O2 was financed by the ethical investment platform Abundance Investment as well as being supported by the Scottish government and the European Union. Orbital Marine’s goal is to commercialize this technology to play a role in tackling climate change using this new green energy technology.

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The world’s most powerful tidal turbine is now generating power

Photo, posted June 12, 2015, courtesy of David Stanley via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.