Whitetopping is an engineered method of placement of concrete overlay on existing distressed bituminous as well as concrete roads. In India, whitetopping technology is being adopted at a very fast rate not only as a measure for overcoming commonly occurring distresses in bituminous roads but also for the purpose of enhancing load carrying capacity of the roads. Currently, this technology is being adopted for colonies and street roads of cities at a large scale. The thickness of whitetopping generally varies from four inches to ten inches. Based upon the thickness of the concrete overlay, it is known as ultrathin, thin, and conventional whitetopping. Whitetopping has immense potential to result in a stronger and more durable pavement with respect to bituminous pavements. This technology provides several advantages over new construction on virgin sub-grade and granular or treated bases as well as bituminous overlays.
The asphalt pavement mix has a visco-plastic behaviour. Therefore, it is common to experience functional distresses such as rutting of the pavement surfaces and general deterioration, which reduce step by step the comfort for the road user. In our country, it is very common to see placement of an overlay of bituminous layer after each monsoon or at a period of 3-5 years as a measure of restoring the functional characteristics of the bituminous pavement. The general deterioration due to common distresses occurring in a bituminous road is shown in Figure 1.
Figure 1: General deterioration in a bituminous pavement
The bituminous overlays have remained popular mainly due to its amenability to stage construction and comfort levels of construction methods among engineers. This type of periodical overlay of the damaged bituminous roads not only consume scarce materials at a regular period but also increases the pavement surface levels from time-to-time leading to several problems especially in moderately to thickly populated areas. In this current era of sustainable development, total transportation cost, rapidly changing traffic scenario (in terms of volume as well as axle loads), rapid developments in concrete technology and mechanization both in production and its laying etc., whitetopping i.e. concrete overlay is becoming a choice for the repairs and rehabilitation along with capacity augmentation of damage roads in India, particularly in cities.