October 15, 2001

Unique Laboratory Offers State-of-the-Art Materials Structures Testing

NC State University's Constructed Facilities Laboratory is
one of the top testing facilities in the US.

A new facility at NC State University, unprecedented in the U.S., has much to offer the civil engineering community.  The Constructed Facilities Laboratory (CFL) on Centennial Campus, a $4 million structure built four years ago and equipped with a National Science Foundation grant, contains a variety of testing equipment, some of which is the largest in the nation.  According to Dr. Sami Rizkalla, Distinguished Professor of Civil Engineering and Construction and director of the CFL, the laboratory is one of the top testing facilities in the country.

For example, the CFL has space and equipment to test a full-sized bridge, which was delivered to the CFL using cranes that can lift 40 tons.  The bridge was subjected to stresses until it collapsed; from this experiment the students and engineers determined the mechanisms of failure.

Other furnishings include an environmental chamber that can test the effects of salt water, humidity and temperature on structures and a shaking table that can simulate earthquake forces up to 12 Hertz.  In the geotechnical laboratory students and engineers conduct research on soil/structure interactions. Much of the research currently conducted at the CFL relates to testing advanced composite materials.  For the past ten years, Fiber Reinforced Polymer (FRP) materials have been of great interest to engineers concerned about infrastructure deterioration, which is becoming an international crisis as existing buildings, roads and bridges begin to weaken over time.

Fiber Reinforced Polymer materials are high-density fibers that can be used to produce structural components for a variety of construction projects.

FRP materials made from glass are non-corrosive and twice the strength of steel.  Even more interesting are carbon FRP, which are six times as strong as steel and only 20 percent of its weight.  This high-strength material is used to produce many shapes and forms.  The fibers are made of silica (sand), coal or petroleum products that are heated to extreme temperatures until they melt, then pressed through a screen and quick-frozen.  The processed fibers are bound together to produce products that are used to build various types of structures and to strengthen existing buildings and bridges.  

The advantages and uses of FRP materials are legion.  Bridges built from these materials can be constructed in a day because no curing is required.  Because the materials are so lightweight, they can be transported easily to remote locations.  Sheets of the material can be used as "wallpaper" to wrap existing structures and prevent damage from routine wear or from earthquakes as well as blasting impact.

Many possibilities for research and testing exist at the CFL, according to Rizkalla.  "It is my goal not only to use these facilities for our research, but also to reach industry and let them know about the testing facilities we have here," he said.  "We want them to feel welcome to use our equipment and expertise for development and testing of new products."

Companies are already signing on to work with the CFL.  Martin Marietta is developing a new generation of bridge deck from glass FRPs to replace reinforced concrete.  Bally, a Morehead City producer of environmental chambers and refrigerator units, is currently working with the CFL, which will be evaluating their products to examine their applicability to the code for new materials testing.  Another company, MMFX Steel Inc., headquartered in Charlotte, is considering an alliance with the CFL to test their new high-strength steel reinforcement, which is resistant to corrosion.

The CFL follows American Concrete Institute (ACI) guidelines for design and construction of buildings and is in the process of obtaining certification from the International Conference of Building Officials (ICBO). ICBO certifies that technical laboratory equipment is properly calibrated.

All in all, the future is bright for the CFL, according to Rizkalla:  "We want everyone to know that the CFL exists and that we are equipped to perform many civil engineering tests and functions with new materials and new facilities here in North Carolina to serve the industry, enhance the economy of the state and contribute to the advancement of knowledge in civil engineering.  The future of the CFL is really only limited by the imagination."

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Media Contacts: Dr. Sami Rizkalla, 919/513-4336, Sami_Rizkalla@ncsu.edu, Linda E. Rudd, 919/515-3848, linda_rudd@ncsu.edu