Research Highlights

Bridge Endurance

Civil Engineering StudentsCivil Engineering faculty members Justin Marshall and Brian Anderson led undergraduate student Patrick Kimmons, below, and graduate students Luke Meadows, behind ladder, and Jared Jensen, above, in testing a bridge’s endurance for real-world use in the Harbert Structures Lab. A full-scale, 20-foot span precast concrete specimen was donated by Foley Arch, a company based in Winder, Ga., for the team to test how much load the bridge could carry. When applying pressure to the bridge, the team examined cracks and looked for damage. The bridge was tested to failure after the team applied more than 190,000 pounds of pressure using three actuators and four high-strength rods.

Lightweight Concrete

Student WorkingFaculty member Anton Schindler and graduate student Benjamin Byard, left, researched the effect of lightweight aggregates (LWA) and curing temperature on the cracking tendency of bridge deck concrete. Cracking of concrete occurs when the induced tensile stress exceeds the tensile strength of the concrete. The strength of concrete is impacted by concrete composition, the properties of its ingredients, the curing method and the temperature history that the concrete experiences. The development of in-place stresses is affected by shrinkage, stiffness, the coefficient of thermal expansion, the application and restraint conditions, the stress relaxation and the temperature history of the concrete. Because the properties of concrete are always changing due to the hydration of the cementing system, it can be difficult to capture their combined effect. Rigid cracking frame testing techniques use instrumented frames that restrain concrete samples from shrinking. The stress in the concrete that is measured is due to the net behavior of all of the aforementioned effects. This research evaluated the effect of LWA and placement temperature using rigid cracking frame testing techniques. Using concrete temperature modeling software, the temperature history of a given concrete mixture can be modeled for a specific application, place and time of year. Software was used to develop a temperature profile of a bridge deck construction in Montgomery for summer and fall conditions. The concrete samples were tested under constant temperature curing condition and were match-cured to the bridge deck temperature profile. The use of LWA was found to be effective in reducing the stress in the concrete, which should improve the performance of bridge decks placed with this concrete type.

Erosion and Sediment Control

Erosion ControlAs new guidelines have been proposed regarding construction site runoff, erosion and sediment control is quickly becoming a focus within the construction industry. To address these new regulations, the Alabama Department of Transportation has teamed with Auburn’s Highway Research Center to develop methods for evaluating erosion and soil control best management practices (BMPs) used at highway construction sites. The current challenge facing the industry includes a lack of scientific understanding on traditional BMPs and the utility of new technologies that are constantly introduced. Therefore, a standard means to evaluate these BMPs using both intermediate-scale and field-scale testing is needed. In response to this need, an innovative testing facility has been designed to conduct both intermediate-scale and field-scale testing under controlled conditions to evaluate current and future erosion and sediment control BMPs. The intermediate-scale experiments are designed to mimic real-world conditions experienced on highway construction sites and are conducted under simulated rainfall. The field-scale facility focuses on testing different ditch check practices as well as drop inlet protection devices with respect to sediment control.

Last Updated: Apr 08, 2015