Out of Africa: Henrique Reis draws on the lessons he learned in Angola
In many ways, Henrique Reis was like any other teenager who loved hot rods in the 1950s and ’60s—always tinkering with engines and rehabilitating old cars. But there was one important difference. Unlike most American hot rod enthusiasts, Reis recalls the thrill of riding land rovers in the midst of a thundering herd of wildebeests.
Reis was born in Portugal, but after age two he spent his formative years in Angola, where his family raised their own chickens and were not surprised to see cheetahs, lions, and hyenas in the wild. Reis also learned to be self-sufficient.
“I lived in a low-density area of Angola, so there were no mechanics around,” he says. “If something broke, you needed to fix it yourself.”
Today, Reis is a professor of Industrial and Enterprise Systems Engineering, and he continues to “tinker” in his University of Illinois laboratory—but it’s a different kind of tinkering. For over 35 years, he has turned his talents to the integrity of materials and structures such as wood, asphalt concrete, tires, glass, steel components, and more.
In recognition of a career devoted to the nondestructive testing of materials, Reis has received three major awards in the past year alone. He won the Founders Award from the American Society of Mechanical Engineers, as well as two awards from the American Society for Nondestructive Testing—the 2016 Research Award for Sustained Excellence and the Outstanding Paper Award.
The Outstanding Paper Award was for a research article in the October 2015 issue of Materials Evaluation; this article features some of the research that Reis’s lab has done on “rejuvenators” and how they can extend the life of asphalt concrete pavements. He will be recognized at ASNT's 2016 fall meeting.
According to Reis, rejuvenators have the potential to make potholes—the scourge of city streets—a thing of the past.
Asphalt concrete contains two primary materials: a binder and aggregates, or crushed stone, he explains. During cold weather, all materials contract, but binders can contract over 10 times more than the aggregates in asphalt concrete.
When winter temperatures strike, the stone aggregates restrict the binder’s ability to contract, which develops tensile stresses in the binder; at the same time, due to the cold temperatures, the binder “becomes basically like glass.” Inevitably, the fragile binder cracks and moisture seeps into the concrete, setting off the process of deterioration that creates the dreaded potholes.
Binders in Illinois are designed to prevent cracking down to about minus twenty-two degrees Fahrenheit, Reis says. But as asphalt concrete ages, it loses some of its cold-weather resistance to wear and tear. Rejuvenators restore the asphalt concrete to its original, crack-resistant state.
When highway crews repair asphalt concrete, they typically scrape off the top two inches, where most of the damage is located. But Reis says that if cities and states applied rejuvenators on a regular maintenance schedule, roads would not have to be repaired nearly as often.
He compares rejuvenators to skin creams that people use in an effort to turn back the clock and revitalize their skin. Concrete rejuvenators revitalize the “skin” of our roads, giving it new life.
Reis was first drawn to engineering as a youth in Angola, and he majored in mechanical engineering at the University of Luanda (currently named University of Agostinho Neto) in the country’s capital. He came to the United States in 1973, when he travelled to MIT to do his graduate work.
Despite having English language skills that he described as “atrocious” when he arrived in the United States, Reis aced his first four classes and went on to receive his master’s degree in 1975 and PhD in 1978, both from MIT. His graduate work was on “dynamic plastic buckling of shells,” where he studied the response of shell-like structures to severe transient loads like underwater habitats.
He landed the job at Illinois in 1980, after teaching engineering in Brazil for a year. Since then, he has been teaching courses in advanced strength of materials, materials response, nondestructive evaluation, and design, in which he stresses the need to design components that are easily inspected and monitored.
Meanwhile, he says he stumbled “by accident” into the research area that would become his life’s work—nondestructive testing of materials and structures.
In the late 1980s, a company asked him to do nondestructive testing of compressed fiberboard to find out which ones swelled the most when exposed to humidity. For this, he received an equipment grant from the National Science Foundation, launching him into a new and productive area of research.
Nondestructive testing does just what it says: it relies on all types of non-invasive procedures, such as ultrasound, to test materials. Reis compares it to visiting a doctor and going through a battery of non-invasive tests to get a diagnosis on your health without exploratory surgery.
After beginning his research in wood, Reis went on to apply nondestructive testing to all sorts of materials and structures. For instance, his lab developed an instrument that could test the integrity of tire sidewalls. In 2000, the Ford Motor Company and Firestone Tire Company came under fire because of the high incidence of tire deterioration in certain vehicles, so there was a need to find a way to test for potential problems.
Underinflated tires accumulate damage faster than properly inflated tires on 18-wheel trucks, Reis says, and this can lead to what is called a “zipper mode of failure,” in which the tire comes apart, like unzipping a jacket. The danger is that when a truck tire becomes fatigued, reinflating it can be dangerous, he says. The tire can burst with such force that it can decapitate the trucker filling it with air.
When a tire is fatigued and its filaments are damaged or broken, the propagation of ultrasound waves through the tire will change. Knowing this, Reis’s lab built an instrument that sends ultrasound waves through the tire sidewalls to determine the tire casing’s structural integrity. It was the first instrument to do this.
In addition to tires, Reis has tested the strength of windshields. He says that the ability of windshields to resist penetration and shattering depends on the adhesion between the plastic interlayer and the two adjacent glass plates. Once again using ultrasonic guided waves, Reis became the first to develop an instrument that measures the adhesion between the two layers of glass and the plastic interlayer in the middle.
In his most recent work, Reis has found a way to detect and assess damage in steel pressure vessels due to high temperature hydrogen attack (HTHA) at oil refineries. As one example of the danger of this mode of failure, a 2010 explosion at the Tesoro Refinery in Washington State was caused by HTHA damage in a heat exchanger, killing seven workers.
According to Reis, “Any time you have hydrogen under pressure and high temperatures, the H2 molecules become 2H and can migrate into the steel. There, they combine with the carbon in the steel, creating high-pressure methane bubbles within the steel.”
These micron-sized methane bubbles grow with time and can form cracks in the steel, which leads to failure of the vessel with the potential for explosion.
“There had been no method to detect this mode of failure before it was too late, but we have found a way, using non-linear ultrasonics,” he says.
Whether it’s asphalt pavements, steel refinery pressure vessels, or bridges, materials deteriorate—sometimes at alarming rates. Reis says that when he was with a group of researchers at a conference in Chicago, they toured the river and were shocked to see the condition of many bridges.
“The bridges were corroded and in a complete state of deterioration,” he says.
Later, he attended a conference in Nantes, France, where he also went on a river tour, and he noted the difference in the bridges there. In Nantes, he says, “There were also old bridges, but they were well taken care of. They were well painted, with no signs of corrosion. If you don’t nurture structures such as bridges, if you don’t rehabilitate them, the damage keeps accumulating. And it gets to a point at which it’s very difficult to rehabilitate.”
Reis learned about the importance of maintenance at an early age, when he lived a more isolated existence in Africa, and they had no choice but to take good care of their tools and other equipment. He also learned from a young age to make do with limited resources—a habit he continues in his lab today. He says he always keeps an eye out for laboratories that are shutting down and selling off equipment.
“Any time I see equipment on sale, I try to bargain for it,” he says. “There is always room for more equipment.”
As he puts it, “Old habits die hard.”