From Cambodia to Carolina: Senior looks to engineer safer buildings for all budgets

Narong Phal has witnessed the same problem in two very different parts of the world.

Growing up in his native Cambodia, the aspiring engineer saw buildings that he considered structurally unsound given the natural hazards of their environs. Phal moved to South Carolina at age 20, and he sees similar risks here in the most seismically active state on the East Coast.

He hopes that his undergraduate research at USC might bring safer buildings to Cambodia, the U.S. and many places in between.

The focus of the senior civil engineering major is an inexpensive, sustainable form of construction: stabilized earth masonry. The research team he’s on is showing how effective earth masonry can be in the face of natural hazards, such as tornadoes and earthquakes.

Phal is working under the tutelage of civil engineer Fabio Matta in the structures and materials laboratory of USC’s College of Engineering and Computing. Matta has done extensive research with stabilized earth masonry, which has a number of advantages over other kinds of masonry, such as concrete blocks or bricks fired in an oven.

Matta’s team prepares stabilized earth blocks suitable for earth mortar-based construction by compressing clay-containing soil with a small amount (just 6 percent by weight) of cement.

“We use little cement and the blocks are not fired, so they have a very small carbon footprint,” Matta says.

And the primary raw material is plentiful. “South Carolina has a lot of this soil, you can find it almost everywhere,” Phal says. Remote regions and farmlands would be particularly well served, he adds, because earth masonry can be prepared locally.

Although they’re still working with prototypes, Matta says all these factors together should make earth masonry a very affordable and energy-efficient product.

There’s also an inherent sturdiness in the system. Ongoing work at USC supported by the National Science Foundation (NSF) is demonstrating that earth masonry can stand up to the wind and debris of extreme weather like hurricanes and tornadoes.

The NSF-funded SC STEPS to STEM program was instrumental in bringing Phal into Matta’s lab. The program helps smooth a student’s transition from a regional campus or community college into the challenging scientific, technology, engineering and mathematics (STEM) programs at USC.

Phal, who spent several semesters at Trident Tech before transferring to USC, used an internship grant to spend a summer working in Matta’s lab.

“It turned out so well, I wanted to keep him even after the scholarship had ended,” says Matta. “You have to be dependable and hard-working, and Narong is very resourceful, but you also have to have the right attitude to work in a group. Working on a team is very important, and he fits right in.”

Matta is now moving on to study earthquake resistance, which is of particular concern in the Palmetto State, the site of a powerful magnitude-7 temblor near Charleston in 1886. He and doctoral candidate Mabel Cuéllar helped Phal prepare a successful Magellan Scholar grant proposal for a study of seismic resistance in earth masonry.

The three are now working on a one-year pilot project to test small walls of plain and fiber-reinforced earth bricks under shear and compressive loads. The reinforcing plastic fibers might be sourced from recycled bottles, making the use of the bricks even more environmentally friendly.

Phal is a first-generation college student, and the Carolina experience is just what he hoped for when he came to America. “I think choosing USC for my education is one of the best decisions of my life,” he says. “I have been in class with a lot of experienced and knowledgeable professors. They not only teach me in class but are also helping me navigate to prepare for my career.”

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