An optimal joint configuration has been developed for concrete overlays, the panels are 6 feet long by 6 feet wide by 6 inches thick; 6 x 6 x6. This standard configuration minimizes moment axle loadings, which in turn, reduces slab curling. And so the term "ultra thin whitetopping" is out. BCOA, for bonded concrete overlay of asphalt, is in. BCOAs are one of five freshly designated variations of concrete overlay designs.