July 12, 2012
Creating safer roads: Civil Infrastructure Systems Laboratory has cemented status as premier testing facility
When it comes to testing materials for road construction, real conditions are a must. But financial limitations and security concerns often preclude such large tests from occurring in the field altogether.
That's where one Kansas State University laboratory can help. The Civil Infrastructure Systems Laboratory is one of only six facilities in the nation capable of testing large-scale asphalt and concrete pavement sections under full-scale loading. The tests are possible because of the laboratory's advanced equipment.
This equipment includes a self-reacting test frame in which a bogie with a dual-wheel assembly repeatedly moves forward and backward on the test pavement while load -- up to legal highway load limit -- is applied on the axles through hydraulic cylinders reacting against two longitudinal girders. Bridge sections as long as 20 feet can be tested in the lab's test pits. At the lab, researchers also can apply lateral traffic wander to simulate highway truck traffic distribution in the lane, and they can control pavement temperatures between -10 and 140 degrees Fahrenheit.
Other equipment utilized for testing includes: a 4,500-square-foot high bay area used to test full-scale structural elements, two MTS hydraulic pumps, two controllers to apply cyclic loading, two data acquisition systems, and several hydraulic rams and load cells to test full-scale members such as concrete beams and prestressed concrete railroad ties.
The Kansas Outdoor Concrete Exposure site is also located at the laboratory, which is three miles from K-State's main campus. The site was built to measure the durability of concrete materials under long-term, realistic exposure conditions.
"It's really nice in that we have outdoor field exposure sites close by, right next to a laboratory, where we can very easily study climactic conditions on concrete pavements and structures," said Kyle Riding, assistant professor of civil engineering. "There are only a few in North America."
The lab is also different because it is fully owned by the university, where state departments of transportation typically own such facilities.
A variety of research projects have been conducted at the facility by Kansas State University professors, as well as their corporate and governmental partners. Bob Peterman, the Martin K. Eby distinguished professor in engineering, examined bridge issues in western Kansas at the facility. The bridges had severe cracks because of frequent usage by overloaded grain trucks and movement of oil derricks. In response, officials in one county removed a bridge, and its girders were brought to the laboratory for evaluation of possible repair techniques. A team of researchers discovered a low-cost option allowing for repair instead of replacement.
Riding is currently conducting research at the concrete exposure site through a Kansas Department of Transportation grant. He is examining how the strength and permeability of concrete develops over a period of several years with realistic exposure. Eight-by-9-foot slabs have been placed outside during different seasons to test effects on the permeability. Permeability is a primary factor in determining the durability of concrete and deals with how easy it is for water to enter a substance.
"Concrete is a permeable material and if water gets in, it causes freeze-thaw damage. The water can carry chlorides, which are the cause of corrosion in reinforcing steel," Riding said. "You want to keep the water out. The less permeable the concrete is, the better."
International collaborations also are occurring at the laboratory. Researchers like Mustaque Hossain, the univerity's Munger professor in civil engineering and associate director of the Mid-America Transportation Center, is working with TenCate, a Dutch company that develops functional materials through a combination of textile technology and chemical processes. The partnership is aimed at developing a new cost-saving type of fabric for roadways. The laboratory presents a number of benefits for testing the fabric that cannot be found anywhere else.
"If you test it here in the laboratory but under the actual traffic conditions, which you can simulate, and real sections which you can build," Hossain said. "It's what's actually going to go on the road. That's good enough to know how it's going to behave in the real world."
The laboratory had auspicious beginnings. K.K. Hu, a longtime professor of civil engineering, invented a new type of dowel in the mid-1990s that could be used for concrete pavements. An interested company that wanted to test the dowel contacted Hu. After examining the costs of testing at the necessary facility, Hu and Hani Melhem, professor of civil engineering, worked with Don Rathbone, then dean of the College of Engineering, who engaged donors to develop and construct the laboratory. The laboratory, which opened in December 1996, was also supported by an economic development grant from the state of Kansas.