Researchers from National Institute of Standards and Technology have developed a new technology that will help people detect early signs of deterioration in a building.
The new technology is based on the same principle as X-ray, CT scan or MRI, but in a more powerful form to trace damage in a wall or across the whole steel framework like bridges, roads and other aging physical infrastructure. The noninvasive technique reveals the scale of corrosion before it causes any significant damage to structure’s foundation. Researchers explain how their team’s system can see through walls and detect corrode.
When water and oxygen damage iron, they leave by-products, with the two most common being goethite and hematite.
“The brown rust that forms when you leave a hammer out in the rain is mostly goethite, and when a steel reinforcing bar (rebar) corrodes inside a concrete bridge deck, that is mostly hematite,” said NIST physical chemist Dave Plusquellic. “We have shown in our new study with goethite, and our previous work with hematite, that terahertz radiation – electromagnetic waves with frequencies 10 to 100 times higher than the microwaves used to cook food – can detect both corrosion products in the early stages of formation.”
People usually assess corrosion with the physical changes on a structure like cracks in exterior bricks or displaced molding. These warning signs show that more dramatic changes are already taking place in a foundation.