The engineering department of the Lafayette (LA) Consolidated Government is incorporating Internal Curing using prewetted ESCS fine aggregate in all of the new bridges in its ongoing Bridge Replacement Program Replacement Program. LCG’s first use of Internal Curing (IC) was in a small five span bridge on West Congress Street in the west end of the parish. For the West Congress bridge, which was built in 2015, LCG tested IC in the deck concrete for spans 1 and 5, as well as the approach slab on the east end of the bridge and the south guard rail wall. The decks for spans 2, 3 and 4, the north guard rail wall and the west approach slab used the “control” concrete without IC. Within the first year, cracks were visible in some of the control concrete, but to date there are still no visible cracks in any of the concrete with IC.
Tyson Rupnow, Ph.D., P.E., Associate Director of Research at the Louisiana Transportation Research Center (LTRC), authored a study of IC for the Louisiana Department of Transportation and Development (LADOTD), which included testing and monitoring at West Congress. LTRC also assisted LCG in its implementation of IC in its Bridge Replacement Program.
“IC helps reduce concrete cracking, thus allowing us to increase the service life of our deck structures and reduce overall maintenance costs,” says Rupnow. Calling IC a “great tool for bridge engineers and designers,” Rupnow said that if the process helps extend bridge service life and strength, then it should be looked at more closely for upcoming projects.
Based on the results at West Congress, LCG has modified its bridge specifications to include IC in all its new bridges. In the new bridge specifications, IC is required in all of the exposed concrete: diaphragms, deck surfaces, guard rail wall and approach slabs. City-Parish engineers have made this change because they believe the reduced cracking will result in longer service life and reduced maintenance costs, giving the local taxpayers more value in their infrastructure projects. LCG is replacing three bridges this year, with IC specified in the concrete for all three.