A Purdue University team developed a method and equipment to better repair paved roadways and highways using electrical resistance measurements to measure the optimum curing time for asphalt emulsions. Source: Purdue University Researchers from Purdue University have been working on new technology that may one day help cut back on the number of road closure and detour signs and traffic cones that inspire dread in many a driver.

That technology, according to Purdue researchers, could better determine if a recently repaired chip-sealed road is ready to return to service.

Researchers relied on electrical resistance measurements to determine when emulsified asphalt in a chip seal had cured adequately enough to support traffic without incurring damage.

According to researchers, this technique helps to ensure that road repairs are done accurately and more quickly than current methods.

"Typical approaches to quantify emulsified asphalt-based chip seal curing times are varied and qualitative," said John Haddock, a professor of civil engineering and the director of the Indiana Local Technical Assistance Program, who leads the research team. "Having a quantitative, real-time measurement method can help construction crews make good decisions that result in a quality chip seal project with minimal traffic disruption."

Current techniques for determining if a recently chip-sealed roadway has the mechanical strength to return to service are insufficient. Generally, field personnel are left to assess whether the emulsified asphalt has sufficiently cured — a method that is subjective and that could result in the abbreviated service life of the pavement.

"Our equipment can help ensure quality of materials used on the project, prevent minimal windshield claims and chip seal repair work, prevent unnecessary construction delays, provide safety for the public and construction workers, and ensure a successful chip seal project," Haddock said.

During Purdue's field testing, chip-seal systems experienced gains in mechanical strength when the initial electrical resistance measurement increased by a factor of 10.