Whitetopping

Whitetopping is suitable for asphalt pavement with little deterioration, although repairs can be made to the asphalt if necessary. If the pavement is badly damaged, it should be completely removed and a new concrete pavement should be installed. The pavement should be relatively hard, as well. Deterioration of overlays is significantly increased on asphalt bases with high viscosity. If a grade or a distance between the pavement and a bridge needs to be preserved, the asphalt can be milled so that the height of the pavement does not change. However, whitetopping requires the asphalt layer to be at least 7.5cm (3") thick. If necessary, a section of new concrete roadway can be placed under a bridge with gentle slopes on either side that meet up with the whitetopped portions of the road.

History and development

The practice of resurfacing distressed asphalt pavements with Portland cement concrete overlays—later termed whitetopping—emerged in the United States during the mid‑20th century as transportation agencies sought longer‑lasting rehabilitation methods than conventional asphalt overlays.

By the 1980s and 1990s, research sponsored by the Federal Highway Administration, FHWA and state departments of transportation refined design methods and construction practices. These studies demonstrated that thinner concrete overlays, when properly bonded to the asphalt substrate, could provide durable and cost‑effective service. This led to the classification of thin and ultrathin whitetopping (UTW), with thicknesses ranging from 5 to 15 cm, suitable for urban streets, intersections, and parking facilities.

Minnesota and Colorado became early leaders in field implementation. The Minnesota Road Research Facility, MnROAD constructed test sections in the 1990s to evaluate bonded overlays under varying traffic and climate conditions, producing influential performance data that guided national specifications. Similarly, Colorado’s “thin whitetopping” projects provided some of the first large‑scale demonstrations of bonded overlays on high‑volume roads, showing significant improvements in rutting resistance and surface durability.

International adoption followed in the late 20th and early 21st centuries, with agencies in Europe and Asia incorporating whitetopping into pavement management strategies. Studies highlighted its potential for extending pavement life cycles, reducing maintenance frequency, and lowering long‑term costs compared with repeated asphalt overlays. Today, whitetopping is recognized as a mainstream rehabilitation technique, with ongoing research focusing on optimizing panel size, fiber reinforcement, and sustainable construction practices.