Thin concrete pavements, constructed over an existing base layer, present an economical choice for low- and moderate-volume roads. However, these thinner pavements are more susceptible to distress from traffic loads and environmental factors. Recent research from the University of Minnesota suggests that adding synthetic fibers to the concrete mix could significantly improve durability and extend pavement lifespan, writes Megan Tsai for CTS News.
Led by long time ISCP member Dr. Manik Barman, an associate professor of civil engineering at the University of Minnesota Duluth, the study explored how pavement-specific synthetic fibers can mitigate transverse joint faulting—a common issue in thin concrete pavements. This faulting, characterized by a difference in elevation between adjacent concrete slabs, occurs due to inadequate load transfer at joints, creating an uneven driving surface.
Traditional concrete pavements rely on dowel bars or aggregate interlock to transfer loads between slabs. However, for pavements less than 7 inches thick, dowel bars are not an option, and aggregate interlock is often insufficient due to the pavement’s reduced thickness. The research team developed a model to analyze how load transfer is distributed among the base layer, aggregate interlock, and synthetic fibers. Their findings revealed that fibers contribute 30 to 40 percent of the pavement’s vertical joint stiffness, complementing the base layer and aggregate interlock to enhance overall performance.
The researchers also introduced a new metric, the “modulus of fiber support,” to quantify the fibers’ contribution to load transfer. In the final phase of the project, various fiber types were tested to determine their effectiveness. Fibers with indentations and irregularities demonstrated superior performance, exhibiting higher peak load resistance and toughness. Moving forward, the research team aims to refine these fiber designs and develop a screening test to assess their suitability for concrete pavement applications.
This research, a pool-funded initiative of the National Road Research Alliance administered by MnDOT, underscores the potential of fiber-reinforced thin concrete pavements in improving road longevity and performance. By integrating advanced synthetic fibers, transportation agencies may achieve more resilient and cost-effective pavement solutions for the future.
Read more here: https://www.cts.umn.edu/news-pubs/news/2024/march/concrete