General mechanistic design procedures were used in an improved approach to the design of asphalt surface rehabilitation on about 100 km of divided carriageway road in Dubai. The developed procedure can readily be extended to cover all major roads in Dubai (as data becomes available) and the principles could be adopted by any road organisation for their road network. The procedure includes design charts giving asphalt overlay thickness based on the subgrade and base stiffness (moduli), and the design traffic. The charts were developed from data at locations where the pavement was excavated and tested to determine the actual structure where the pavement history and the pavement condition, age and past traffic were known. The procedure involved developing asphalt moduli-temperature relationships for Dubai, together with the backcalculated pavement layer moduli, determined from falling weight deflectometer (FWD) data and an accurate back calculation moduli procedure (EFROMD2 based on the CIRCLY program). However, accurate back calculation of moduli is unsuitable for large amounts of data (5200 points on this road), so the less accurate ELMOD program (supplied by the FWD manufacturer) was used to determine the pavement layer modulus at each point. For asphalt overlay design purposes, the analysis was developed and considered in terms of homogeneous sections. The developed procedure can take past traffic loading and remaining structural life into account and can address straight overlays, mill and replace overlays, and hot-in-place asphalt recycling. (a).
Abstract