Eastern Alamance High School freshmen Kallie Elam and Josie Gonzalez won First Place in the Structural Engineering competition and the Overall Engineering Prize at the North Carolina Science and Engineering Fair March 29 and 30 at North Carolina State University in Raleigh. The winning project involves concrete and fungus, and is titled, “Fungi Strength.”
Elam and Gonzalez were students in the fall semester with Deryl Smith's Project Lead the Way class of Introduction to Engineering Design at the Alamance-Burlington School System’s Career Technical Education Center.
Their victory at the North Carolina Science and Engineering Fair qualifies Elam and Gonzalez to compete in the Intel International Science & Engineering Fair hosted by the Society for Science and the Public in Phoenix, Arizona May 12-17. Approximately 1,800 students from around the world will be competing in the international event.
Elam and Gonzalez are the first two students from Eastern Alamance High School to earn the Grand Prize at the state event.
“We’re just really excited, because there’s something like 81 countries coming,” Elam said.
On the afternoon of Wednesday, April 3, Elam and Gonzalez presented their project in front of Mr. Smith, CTEC Principal Darrell Thomas, a few parents, and an assemblage of media. Gonzalez and Elam explained the varying components of their experiment, and what exactly they were attempting to test out.
“There’s three different parts of a bridge,” Gonzalez said. “The most common way in which bridges crack and end up collapsing is when the crack forms on the deck. When the concrete cracks, the water gets into the cracks and freezes, making the cracks bigger, and allowing the water to get to the metal, rusting the bridge’s metal components.”
“With the fungi, it would allow when exposed to the conditions of water and the temperature, it would allow the fungi to grow with those thread-like structures, and sort of mend the concrete back, strengthening the bridge back so it wouldn’t crack or break.”
“The way that we came up with this project is we were both interested in engineering. So we decided to do a project in the engineering category,” added Elam. “We did more research, and found that a lot of bridges recently have collapsed. One in Florida and one in Italy - the Genoa Bridge. We researched some more, and we saw that scientists have recently come up with a new method to try to strengthen concrete. It’s very new. Putting fungus into concrete in order to make it stronger, and almost put the concrete back together, if it were to crack.”
Elam explained that the fungus would be part of the concrete laid on the top layer of the bridge - the part on which cars pass directly over.
“That (the roadway concrete) would be the place, in a hypothetical situation, that’s where the fungus would go,” she said. “It would prevent the water from getting to the substructure of the bridge,” she said. “This is a very new concept. If it were to go into an actual situation, we would need a lot more testing. How would the fungus mend the concrete?”
A local representative with Chandler Concrete, along with two engineers from the North Carolina Department of Transportation, helped assist Elam and Gonzalez with expert knowledge on concrete.
The pair of students hypothesized, and then proved, that if one adds certain types of fungus to a concrete mix, it has the capability to improve the strength of the concrete. Depending on the type of fungus, the concrete can also be weakened.
“I came in contact with the concrete specialist. I told him our situation. We discussed it, and conclusion that he came to was that the fungi had affected the ph of the concrete - one making it weaker, and one making it stronger,” Gonzalez said of the results of the experiment.
The students began the experiment by testing two different types of fungi in the trichoderma hypocreaceae genus.
“That had hyphae mycelium, which are thread-like structures, and that could withstand harsh conditions,” Gonzalez explained. “For our science fair project, that type of fungi, a small sample of it was way out of our price range for this project. It was over $300 for a small sample.”
Unable to get the more expensive sample, Elam and Gonzalez went to Carolina Biological, and found different types of less expensive fungi with the same types of characteristics.
“They had the hyphae mycelium, and could withstand the harsher conditions. So we then went on adding this to the regular concrete mixture, and pouring into three different molds, which we later tested.”
The students used approximately three-fourths of the available fungus between three blocks of concrete, mixed with approximately 13.5 cups of concrete, and 15 cups of water. Elam and Gonzalez sat the concrete molds out for a week in the elements before testing the various molds for strength, using water weight to determine their respective breaking points.
“In order to test this, we decided that we would do it in a way that seemed more innovative. We took the concrete blocks, we put two two-inch blocks on the ends of the concrete blocks. And then we put another board on top,” Elam said. “The different fungus affected the concrete in different ways. With the regular concrete, it held about 227 pounds on average. With the “a” (aspergillus) flavus, which is one of the types of fungus that we decided to use, it made it stronger, getting up to 260 pounds. With our other fungus, “a” (aspergillus) chevalieri, it made it weaker, making it only 16.5 pounds. We believe the reason why this happened is the way the fungus affected the ph of the concrete.”
“We believe with adding the fungi, it made the a flavus sample actually dry more and cure more than the other fungi did, and just the plain concrete,” Gonzalez pointed out.
When the concrete is poured and dried, the fungi goes dormant, unless it is exposed to the conditions. So when a crack become exposed to the water, the fungi wakes back up. Then it starts the mending process until it is closed off again, at which time it would once again go dormant.
In theory, this means that the fungus could potentially mend and improve the concrete’s strength during the harsh winter months, while laying dormant during the hot summer months.
“When something like fungus is exposed to the conditions, it is known to grow,” Elam said. “But if it is not, it uses anaerobic respiration, and doesn’t have to use air or oxygen. That’s how the fungus would actually work within the concrete. It’s without the oxygen, it’s still able to live. But if it is exposed to it, it will use anaerobic respiration in order to grow.”
Different types of fungus could work in different types of climates around the country, according to ph levels and other environmental factors.
“With choosing the different types fungus, you would have to use different types of fungus in different areas. The weather conditions are different in different areas. How the fungus would affect concrete would differ.”
The students created small holes into the various concrete molds, which will allow them to assess how the fungus strengthens, weakens, and/or mends the concrete over an extended period of time. Since they have three more years at Eastern High School, Elam and Gonzalez have plenty of time to continue studying and experimenting with this potential breakthrough in modern construction.
“We took straws and poked holes into the molds, in order to create little holes or hypothetical cracks. We were going to see if this made the fungus actually grow within, or if it would make it weaker and cause it to break easier,” Elam said. “One of our judges from a previous competition said what would happen to this after five years or so? Would the fungus still be alive? So we thought if we were to do this in further testing that another thing we would try is see if we were try this testing again after a long period of time.”
“We have other samples that have been exposed to the conditions of the weather this whole time,” added Gonzalez, mentioning that there are molds from the fall semester that were exposed throughout the winter to cold, wet, rainy conditions.
“That’s something that we definitely look forward to testing in the future - how these samples will do over a period of time,” Gonzalez said. “We would take a psi hammer to test if the fungi made it stronger or weaker from November until now. We’re going to take the psi hammer and test it on old samples that have been exposed on conditions from November to now. That would see how the fungus holds up over that span.”
“With the small holes that we’ve poked, we could take a microscope and look in it, and then see if there was any thread-like structures through the microscope in the concrete. Or we could talk to scientists and see if there was a way to test that,” she added.